Deprenyl and Rasagiline

Home , Lazabemide, Rasagiline

Pharmacological Reports 66 (2014) 453–458

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Original research article

Essential difference between the pharmacological

spectrum of (À)-deprenyl and rasagiline

Ildiko´ Miklya

Semmelweis University, Department of Pharmacology and Pharmacotherapy, Budapest, Hungary

A R T I C L E I N F O A B S T R A C T

Article history: Background: (À)-Deprenyl and rasagiline are classiﬁed as selective inhibitors of B-type MAO. The

Received 12 July 2013

DATATOP study revealed that the administration of (À)-deprenyl to untreated patients with Parkinson’s

Received in revised form 19 November 2013

disease (PD) signiﬁcantly delays the need for levodopa therapy (Parkinson Study Group, 1989).

Accepted 26 November 2013

Rasagiline was ineffective in this respect (Parkinson Study Group, 2002). The aim of this paper is to

Available online 3 April 2014

explain the reasoning behind the differentiation between (À)-deprenyl and rasagiline.

Methods: In the shuttle box the acquisition of a two way conditioned avoidance response (CAR) was

Keywords:

analyzed on male Wistar rats during 5 consecutive days. Tetrabenazine-treatment (1 mg/kg sc) depletes

(À)-Deprenyl/selegiline

the transmitters from their stores in the nerve terminals of the catecholaminergic neurons and blocks the

Rasagiline

acquisition of a CAR. Catecholaminergic activity enhancer (CAE) substances [(À)-deprenyl, (À)-BPAP]

Selective inhibition of MAO-B

Catecholaminergic activity enhancer (CAE) fully antagonize the tetrabenazine-induced learning deﬁcit. Using (À)-deprenyl and (À)-BPAP as

effect reference substances, we measured the effect of rasagiline and J-508 in this test. Rasagiline is the

desmethyl-analog of J-508, described by Knoll in 1978.

Results: In contrast to (À)-deprenyl and (À)-BPAP, J-508 and rasagiline were found in the shuttle box test

to be devoid of the CAE effect.

Conclusions: Since convincing experimental and clinical evidence speaks in favor for the conclusion that

the catecholaminergic activity enhancer (CAE) effect of (À)-deprenyl is responsible for the signiﬁcantly

delayed need for levodopa therapy in untreated patients with PD (Knoll, 2012) and rasagiline is devoid of

the CAE effect, this might explain why ‘‘. . .based on current evidence, rasagiline cannot be said to

deﬁnitely have a disease-modifying effect’’ [Robottom, 2011].

ß 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp.

Introduction to the pathogenesis of nigral degeneration, thus, (À)-deprenyl, the

MAO inhibitor, a-tocopherol, the antioxidant, and the combination

Knoll developed E-250, later named deprenyl, an MAO inhibitor of the two compounds will slow the clinical progression of the

with a peculiar pharmacological spectrum in the late 1960s [1]. disease. They selected patients with early untreated PD and

MAO inhibitors are known to potentiate the effect of tyramine, in measured the delay of the onset of disability necessitating

striking contrast, (À)-deprenyl inhibits it. Thus, the compound was levodopa therapy. Their study revealed that only (À)-deprenyl

a MAO inhibitor free of the cheese effect [2]. (À)-Deprenyl became signiﬁcantly delayed the onset of disability associated with early,

famous as the ﬁrst selective inhibitor of MAO-B [3], and known as a otherwise untreated PD, a-tocopherol was ineffective [8].

safe compound to achieve a levodopa-sparing effect in Parkinson’s Knoll’s further studies into the mechanism of action of (À)-

disease (PD) [4,5]. deprenyl revealed that: (i) a peculiar catecholaminergic activity

Later on, the DATATOP Multicenter Clinical Study revealed that enhancer (CAE) regulation is operating in the brain stem’s

the administration of (À)-deprenyl to untreated patients with PD catecholaminergic neurons [9,10]; (ii) b-phenylethylamine (PEA)

signiﬁcantly delays the need for levodopa therapy [6,7]. The is primarily, in low dose range, an endogenous CAE substance and

DATATOP study was originally based on the working hypothesis only in much higher doses a potent releaser of catecholamines from

that MAO activity and the formation of oxygen radicals contribute their intra-neuronal stores [11]; (iii) (À)-deprenyl is a synthetic PEA-

derived CAE substance which completely lost the releasing property

of its parent compound [12]; (iv) (À)-deprenyl exerts its CAE effect

with a highly characteristic dose-dependency, presenting one

E-mail address: [email protected].

http://dx.doi.org/10.1016/j.pharep.2013.11.003

454 I. Miklya / Pharmacological Reports 66 (2014) 453–458

bell-shaped concentration-effect curve in the low pico–nanomolar The rat was put in a box separated inside by a barrier with a small

range (speciﬁc enhancer effect) and another one at a higher gate in the middle, and the animal was trained to cross the barrier

micromolar range (non-specific enhancer effect) [13]. under the influence of a conditioned stimulus (CS, light flash). If it

According to Knoll, in the treatment of PD the usually used failed to respond within 10s, it was punished with the uncondi-

10 mg daily dose of (À)-deprenyl has two effects: it blocks MAO-B tioned stimulus (US), a foot shock (1 mA). If the rat failed to

activity in the brain and exerts its non-speciﬁc enhancer effect. The respond within 5s to the US, it was noted as escape failure (EF). One

CAE effect of the drug is fully responsible for the unique disease trial consisted of a 10 s inter-trial interval, followed by 20 s CS. The

modifying effect of (À)-deprenyl and the selective inhibition of last 5 s of CS overlapped the 5 s US. At each learning session, the

MAO-B is responsible for the safe levodopa-sparing effect of the number of CARs, EFs and inter-trial responses (IRs) were

drug [14]. It is in harmony with this conclusion that a-tocopherol, automatically counted. The tables show the ﬁfth day performances

being devoid of an enhancer effect [15], failed to exert a PD only. Tetrabenazine-treatment (1 mg/kg sc) depletes at least 90% of

modifying effect. norepinephrine and dopamine from their stores in the nerve

Rasagiline (Azilect), the selective inhibitor of MAO-B described terminals of the catecholaminergic neurons in the brain stem. Due

by Finberg et al. [16], was introduced as a possible substitute for to the weak performance of the catecholaminergic brain engine,

(À)-deprenyl. The clinical trial with rasagiline, performed by the the activation of the cortical neurons remains below the level

Parkinson Study Group, revealed that unlike the early selegiline required for the acquisition of a CAR. The learning deﬁcit caused by

trials, rasagiline failed to demonstrate a decreased need for tetrabenazine-treatment can be antagonized by the administration

levodopa [17]. These results further the aim of this study, the of a synthetic CAE substance or an A-type MAO inhibitor, whereas

analysis of the enhancer effect of rasagiline, imperative. selective inhibition of B-type MAO or inhibition of the reuptake of

catecholamines and/or serotonin is ineffective [18].

Materials and methods

Statistical analysis

Experiments were conducted on male Wistar rats (Charles

River), weighing 250–350 g, received from the breeding colony of The data are expressed as the means Æ SEM and were evaluated

Semmelweis University. The animals were kept in a 12-h light– by one-way ANOVA followed by the Newman–Keuls post hoc test.

dark cycle and under condition of controlled temperature P < 0.05 was considered to be statistically signiﬁcant.

(22 Æ 2 8C) and relative humidity (55 Æ 5%). The rats were main-

tained on standard laboratory chow and tap water ad libitum. All Results

procedures conformed to the European Convention for the protection

of vertebrate animals used for experimental and other scientiﬁc According to our previous experiences there are two efﬁcient

purposes. The study was approved by the Animal Ethics Committee of ways to fully antagonize tetrabenazine-induced learning-deﬁcit in

Semmelweis University, Budapest (permission number: 1810/003/ rats trained in the shuttle box: (1) blockade of MAO-A activity and

2004; 22.1/606/001/2010). (2) treatment with a speciﬁc enhancer substance [14, chapter 9].

Via measuring the effect of lazabemide on electrical simulation

Chemicals induced release of [ H]-norepinephrine from the isolated brain

stem, we demonstrated that this drug, introduced into therapy

R-(À)-1-(benzofuran-2-yl)-2-propyl-aminopentane HCl [(À)- after (À)-deprenyl as the second selective inhibitor of B-type MAO,

BPAP], Fujimoto Pharmaceutical Corp., Osaka, Japan; (À)-deprenyl is devoid of the enhancer effect [18]. Table 1 corroborates this

(selegiline), (À)-desmethyldeprenyl, Sanoﬁ-Chinoin, Budapest, ﬁnding. Lazabemide, carefully studied in ten doses exerted, only in

Hungary; lazabemide hydrate, clorgyline hydrochloride, Sigma, the 0.1 mg/kg dose a statistically signiﬁcant, but very slight,

Hungary; tetrabenazine hydrochloride (synthesized by Prof. C. biologically negligible effect. In a small range of higher doses

Sza´ntay, Department of Organic Chemistry, University of Technical (0.25–2.0 mg/kg) lazabemide antagonized the tetrabenazine-

Sciences, Budapest, Hungary). induced increase in the percentage of EFs.

Table 2 shows that clorgyline antagonized tetrabenazine-

Shuttle box test induced inhibition of learning in doses which fully inhibited

MAO-A activity.

In the shuttle box the acquisition of a two-way conditioned The ultimately convincing proof that the CAE effect is a

avoidance response (CAR) was analyzed during 5 consecutive days. previously unknown possibility to enhance the activity of special

Table 1

The effect of lazabemide, a selective inhibitor of MAO-B, in antagonizing tetrabenazine-induced learning deﬁcit.

Series no. Compound (mg/kg) Tetrabenazine (mg/kg) Percentage of CARs Percentage of EFs Number of IRs

1 Saline – 82.33 Æ 3.46 0.00 Æ 0.00 10.67 Æ 3.23

Lazabemide

2 – 1 1.50 Æ 0.85 88.33 Æ 5.92 5.33 Æ 2.70

3 0.00001 1 2.33 Æ 1.31 64.50 Æ 11.56 3.33 Æ 0.88

4 0.0001 1 0.67 Æ 0.33 86.33 Æ 4.93 2.17 Æ 0.60

5 0.001 1 0.83 Æ 0.40 83.33 Æ 5.06 3.00 Æ 0.68

6 0.01 1 4.40 Æ 1.60 51.40 Æ 11.91 3.40 Æ 1.75

* *

7 0.1 1 21.40 Æ 9.35 19.50 Æ 10.84 2.50 Æ 0.92

8 0.25 1 0.33 Æ 0.33 2.67 Æ 1.43 0.00 Æ 0.00

9 1.0 1 0.17 Æ 0.16 1.50 Æ 0.76 2.17 Æ 0.65

10 2.0 1 0.00 Æ 0.00 0.50 Æ 0.34 0.00 Æ 0.00

11 5.0 1 0.00 Æ 0.00 82.00 Æ 10.18 2.00 Æ 0.58

Tetrabenazine or the combination of tetrabenazine + lazabemide was administered subcutaneously, 60 min before daily measurement. Male rats (N = 6) were trained at 100

trials daily for 5 days in the shuttle box. The performance on the ﬁfth day of training is shown in the table. CAR, conditioned avoidance response; EF, escape failure; IR,

intersignal reaction.

Signiﬁcance of combination (tetrabenazine + lazabemide) vs. tetrabenazine (ANOVA): p < 0.001.

I. Miklya / Pharmacological Reports 66 (2014) 453–458 455

Table 2

The effect of clorgyline, a selective inhibitor of MAO-A, on tetrabenazine-induced learning deﬁcit.

Series no. Compound (mg/kg) Tetrabenazine (mg/kg) Percentage of CARs Percentage of EFs Number of IRs

1 Saline – 82.33 Æ 3.40 0.00 Æ 0.00 10.67 Æ 3.23

Clorgyline

2 – 1 1.50 Æ 0.85 88.33 Æ 5.93 5.33 Æ 2.70

3 0.00001 1 6.67 Æ 4.15 57.67 Æ 13.64 3.17 Æ 1.58

4 0.0001 1 5.50 Æ 4.71 64.17 Æ 27.38 2.17 Æ 0.48

5 0.001 1 2.00 Æ 0.82 44.50 Æ 12.40 3.67 Æ 1.23

6 0.01 1 2.00 Æ 1.00 73.33 Æ 8.55 2.67 Æ 1.09

*** ***

7 0.1 1 90.50 Æ 2.05 0.00 Æ 0.00 23.50 Æ 7.61

*** *** **

8 0.25 1 84.60 Æ 4.70 0.00 Æ 0.00 37.20 Æ 11.75

Signiﬁcance of combination (tetrabenazine + clorgyline) vs. tetrabenazine (ANOVA): p < 0.05.

Signiﬁcance of combination (tetrabenazine + clorgyline) vs. tetrabenazine (ANOVA): p < 0.01.

***

Signiﬁcance of combination (tetrabenazine + clorgyline) vs. tetrabenazine (ANOVA): p < 0.001.

Table 3

The effect of (À)-BPAP, the tryptamine-derived speciﬁc enhancer substance, on tetrabenazine-induced learning deﬁcit.

Series no. Compound (mg/kg) Tetrabenazine (mg/kg) Percentage of CARs Percentage of EFs Number of IRs

1 Saline – 82.33 Æ 3.40 0.00 Æ 0.00 10.67 Æ 3.23

(À)-BPAP

2 – 1 1.50 Æ 0.85 88.33 Æ 5.93 5.33 Æ 2.70

*** ***

3 0.00001 1 62.00 Æ 9.60 5.17 Æ 2.20 29.00 Æ 7.55

*** ***

4 0.0001 1 73.50 Æ 7.37 2.33 Æ 2.14 13.67 Æ 1.99

** *

5 0.001 1 42.83 Æ 18.97 46.17 Æ 20.81 11.00 Æ 6.67

6 0.01 1 8.83 Æ 7.49 72.50 Æ 16.09 1.00 Æ 0.52

*** ***

7 0.05 1 83.00 Æ 2.78 0.17 Æ 0.17 11.83 Æ 5.19

*** ***

8 0.1 1 75.60 Æ 5.55 2.60 Æ 2.60 9.80 Æ 5.31

*** ***

9 0.25 1 66.80 Æ 15.09 6.20 Æ 5.21 11.20 Æ 2.85

*** *** **

10 2 1 95.00 Æ 1.26 0.00 Æ 0.00 47.33 Æ 11.27

*** *** ***

11 10 1 92.00 Æ 2.46 0.00 Æ 0.00 68.33 Æ 26.46

4 peak dose with the speciﬁc enhancer effect.

7 peak dose with the non-speciﬁc enhancer effect.

10 and 11 doses which inhibit MAO-A activity.

Signiﬁcance of combination (tetrabenazine + (À)-BPAP) vs. tetrabenazine (ANOVA): p < 0.05.

Signiﬁcance of combination (tetrabenazine + (À)-BPAP) vs. tetrabenazine (ANOVA): p < 0.01.

***

Signiﬁcance of combination (tetrabenazine + (À)-BPAP) vs. tetrabenazine (ANOVA): p < 0.001.

neuronal systems in the brain stem was the development of R-(À)- (À)-BPAP is 100.000 times higher than the peak dose with the

1-(benzofuran-2-yl)-2-propylaminopentane [(À)-BPAP], the pres- speciﬁc enhancer effect. Such high doses obviously stimulate or

ently known most potent CAE substance which in contrast to (À)- block many unknown systems. It was already shown in the ﬁrst

deprenyl also enhances the activity of the serotonergic neurons in paper published on (À)-BPAP that in high concentration the

the brain stem and is free of MAO-B inhibitory potency [19]. compound blocks a2-adrenoceptors, for example [19, Table 4].

To demonstrate the effect of the enhancer substances in this Table 4 shows that although (À)-deprenyl is a much less

test, we used (À)-BPAP as a reference substance. Enhancer effective enhancer substance than (À)-BPAP, we see in this test too

substances exert their peculiar stimulatory effect on enhancer- the characteristic bi-polar, bell-shaped dose/effect relationship,

sensitive neurons with a highly characteristic dose-dependency, the sharp dissociation between the speciﬁc and non-speciﬁc

presenting one bell-shaped concentration/effect curve in the low enhancer effect. 0.001 mg/kg was the peak dose with the speciﬁc

femto–picomolar range (speciﬁc enhancer effect) and another one enhancer effect and 0.01 mg/kg was already ineffective. 0.25 mg/

at a very high, micromolar range (non-speciﬁc enhancer effect) kg, the dose in which (À)-deprenyl fully inhibits MAO-B activity

[13]. was also the peak dose with the non-speciﬁc enhancer effect, and 1

Table 3 demonstrates that (À)-BPAP started to antagonize the and 2 mg/kg (À)-deprenyl were unable to antagonize tetrabena-

effect of tetrabenazine in a dose as low as 0.00001 mg/kg, and the zine-induced learning depression. Due to the inhibition of MAO-A

most effective dose was 0.0001 mg/kg. Due to the bell shaped activity (À)-deprenyl signiﬁcantly antagonized, in very high doses

concentration/effect curve characteristic to the enhancer effect, a (5–10 mg/kg), the effect of tetrabenazine.

sufﬁciently higher dose (0.01 mg/kg) of (À)-BPAP was ineffective. Table 5 shows that regarding the speciﬁc enhancer effect

In the dose range between 0.05 and 0.25 mg/kg (À)-BPAP 0.001 mg/kg (À)-desmethyl-deprenyl acts like (À)-deprenyl. With

antagonized tetrabenazine-induced learning deﬁcit via its non- (À)-desmethyl-deprenyl the bi-modal, bell-shaped dose–effect

speciﬁc enhancer effect. The most effective dose was 0.05 mg/kg relationship characteristic to the enhancer substances is not as

and 0.1 mg/kg (À)-BPAP was ineffective. pronounced as in the case of (À)-BPAP or (À)-deprenyl. Further-

(À)-BPAP inhibits MAO-A activity in very high doses [19]. Due more, since we did not measure in this series of experiments the

to this effect 2 mg/kg (À)-BPAP is the lowest dose which fully effect of (À)-desmethyl-deprenyl in a dose higher than 2 mg/kg, its

inhibits MAO-A activity, thus antagonizing the effect of tetra- ability to antagonize the effect of tetrabenazine via the inhibition

benazine. To demonstrate that as an enhancer substance (À)-BPAP of MAO-A remained undetected.

has an unusually wide safety margin, Table 3 shows that even Table 6 shows that J-508, the parent compound of rasagiline,

10 mg/kg (À)-BPAP was tolerated without any harm. This dose of the pharmacology of which was described in 1978 [20–22], is

456 I. Miklya / Pharmacological Reports 66 (2014) 453–458

Table 4

The effect of (À)-deprenyl, the PEA-derived enhancer substance, on tetrabenazine-induced learning deﬁcit.

Series no. Compound (mg/kg) Tetrabenazine (mg/kg) Percentage of CARs Percentage of EFs Number of IRs

1 Saline – 82.33 Æ 3.40 0.00 Æ 0.00 10.67 Æ 3.23

(À)-Deprenyl

2 – 1 1.50 Æ 0.85 88.33 Æ 5.93 5.33 Æ 2.70

3 0.0001 1 29.00 Æ 19.46 39.33 Æ 11.19 5.50 Æ 3.44

* *

4 0.001 1 42.33 Æ 14.42 35.83 Æ 17.07 15.67 Æ 9.30

5 0.01 1 10.33 Æ 7.37 59.17 Æ 16.60 3.17 Æ 1.28

* **

6 0.1 1 41.83 Æ 8.38 7.33 Æ 4.33 12.33 Æ 3.44

** **

7 0.25 1 76.83 Æ 4.66 0.83 Æ 0.54 7.33 Æ 1.28

8 0.50 1 8.17 Æ 4.69 46.50 Æ 15.98 1.35 Æ 0.76

9 1 1 5.17 Æ 2.75 62.67 Æ 18.39 2.33 Æ 1.56

10 2 1 2.67 Æ 1.09 56.83 Æ 12.46 6.00 Æ 3.38

** **

11 5 1 62.67 Æ 10.53 9.17 Æ 6.04 5.33 Æ 2.73

* **

12 10 1 52.83 Æ 16.12 19.17 Æ 14.74 7.00 Æ 5.00

4 peak dose with the speciﬁc enhancer effect.

7 peak dose with the non-speciﬁc enhancer effect and the optimum dose which inhibits MAO-B activity selectively.

11 and 12 doses which inhibit MAO-A activity.

Signiﬁcance of combination (tetrabenazine + (À)-deprenyl) vs. tetrabenazine (ANOVA): p < 0.01.

Signiﬁcance of combination (tetrabenazine + (À)-deprenyl) vs. tetrabenazine (ANOVA): p < 0.001.

Table 5

The effect of (À)-desmethyl-deprenyl on tetrabenazine-induced learning deﬁcit.

Series no. Compound (mg/kg) Tetrabenazine (mg/kg) Percentage of CARs Percentage of EFs Number of IRs

1 Saline – 82.33 Æ 3.40 0.00 Æ 0.00 10.67 Æ 3.23

(À)-Desmethyl-deprenyl

2 – 1 1.50 Æ 0.85 88.33 Æ 5.93 5.33 Æ 2.70

3 0.0001 1 27.17 Æ 12.08 31.00 Æ 13.89 6.67 Æ 3.45

** ***

4 0.001 1 51.00 Æ 15.05 19.83 Æ 16.12 11.67 Æ 5.35

** **

5 0.01 1 56.33 Æ 13.08 20.33 Æ 15.96 16.67 Æ 4.14

*** ***

6 0.1 1 63.50 Æ 6.77 4.50 Æ 2.35 18.33 Æ 6.97

7 0.25 1 5.40 Æ 2.16 46.20 Æ 15.76 0.80 Æ 0.37

8 0.5 1 7.33 Æ 2.33 49.00 Æ 14.60 4.17 Æ 1.58

9 1 1 1.83 Æ 0.79 66.33 Æ 10.80 3.00 Æ 0.93

10 2 1 0.50 Æ 0.34 95.33 Æ 2.84 2.00 Æ 1.00

Signiﬁcance of combination (tetrabenazine + (À)-desmethyl-deprenyl) vs. tetrabenazine (ANOVA): p < 0.05.

Signiﬁcance of combination (tetrabenazine + (À)-desmethyl-deprenyl) vs. tetrabenazine (ANOVA): p < 0.01.

***

Signiﬁcance of combination (tetrabenazine + (À)-desmethyl-deprenyl) vs. tetrabenazine (ANOVA): p < 0.001.

devoid of the speciﬁc enhancer effect. J-508 fully inhibits curve characteristic to the non-speciﬁc enhancer effect. In contrast

tetrabenazine-induced learning depression in doses higher than to J-508, rasagiline increased signiﬁcantly the inter-trial motility

0.05 mg/kg. J-508 is obviously inducing an amphetamine-type only in the highest (5 mg/kg) dose investigated in this study.

release of dopamine since the inter-trial motility is enormously Table 7 shows also a slight, statistically not signiﬁcant increase in

increased and similarly to the effect of amphetamines this effect of the percentage of CARs in the rats treated with 0.0001 mg/kg

J-508 is in a higher dose (1 mg/kg), due to over-excitation, already rasagiline (Series No. 4) and this slight effect vanished with the

diminished. The safety margin of J-508 is narrow; 5 mg/kg was higher, 0.0005 mg/kg dose (Series No. 5). The same slight effect was

already lethal. detectable with 0.005 mg/kg rasagiline (Series No. 7) and this

Table 7 shows that rasagiline too, like J-508, is antagonizing the effect too vanished when the dose was raised to 0.01 mg/kg (Series

effect of tetrabenazine upwards from the 0.05 mg/kg dose. In this No. 8). Whether these slight non-signiﬁcant changes are signs of a

effective dose range there is no sign of the bell-shaped dose effect very weak speciﬁc and non-speciﬁc enhancer effect remains a

Table 6

The effect of J-508 on tetrabenazine-induced learning deﬁcit.

Series no. Compound (mg/kg) Tetrabenazine (mg/kg) Percentage of CARs Percentage of EFs Number of IRs

1 Saline – 82.33 Æ 3.40 0.00 Æ 0.00 10.67 Æ 3.23

J-508

2 – 1 1.50 Æ 0.85 88.33 Æ 5.93 5.33 Æ 2.70

3 0.0001 1 6.33 Æ 3.85 56.83 Æ 14.61 5.67 Æ 3.16

4 0.001 1 4.67 Æ 1.17 48.80 Æ 4.84 5.83 Æ 1.54

5 0.01 1 7.33 Æ 3.42 45.67 Æ 15.74 5.00 Æ 1.59

*** *** ***

6 0.05 1 83.83 Æ 2.14 2.00 Æ 1.48 103.50 Æ 23.63

*** *** ***

7 0.1 1 91.50 Æ 1.82 0.00 Æ 0.00 128.33 Æ 12.76

*** *** **

8 1 1 86.25 Æ 5.81 0.25 Æ 0.25 41.00 Æ 11.40

9 5 1 Lethal – –

6: lowest dose which inhibits MAO-A activity given in bold.

Signiﬁcance of combination (tetrabenazine + J-508) vs. tetrabenazine (ANOVA): p < 0.05.

Signiﬁcance of combination (tetrabenazine + J-508) vs. tetrabenazine (ANOVA): p < 0.01.

***

Signiﬁcance of combination (tetrabenazine + J-508) vs. tetrabenazine (ANOVA): p < 0.001.

I. Miklya / Pharmacological Reports 66 (2014) 453–458 457

Table 7

The effect of rasagiline on tetrabenazine-induced learning deﬁcit.

Series no. Compound (mg/kg) Tetrabenazine (mg/kg) Percentage of CARs Percentage of EFs Number of IRs

1 Saline – 82.33 Æ 3.40 0.00 Æ 0.00 10.67 Æ 3.23

Rasagiline

2 – 1 1.50 Æ 0.85 88.33 Æ 5.93 5.33 Æ 2.70

3 0.00005 1 1.83 Æ 0.70 75.50 Æ 6.76 4.67 Æ 1.50

4 0.0001 1 26.67 Æ 10.95 47.17 Æ 15.22 8.83 Æ 3.81

5 0.0005 1 11.33 Æ 8.41 50.00 Æ 14.78 5.17 Æ 1.81

6 0.001 1 14.00 Æ 7.82 62.60 Æ 16.83 3.40 Æ 1.11

7 0.005 1 26.33 Æ 11.15 43.17 Æ 18.41 3.67 Æ 1.74

8 0.01 1 17.83 Æ 14.13 73.17 Æ 16.48 8.67 Æ 7.87

** **

9 0.05 1 71.33 Æ 9.03 7.50 Æ 6.38 9.17 Æ 2.90

** **

10 0.10 1 73.17 Æ 9.00 9.33 Æ 8.94 13.17 Æ 6.51

** **

11 0.25 1 69.33 Æ 13.97 11.67 Æ 11.08 23.83 Æ 5.88

** **

12 1.00 1 61.40 Æ 8.17 3.00 Æ 1.64 15.40 Æ 6.14

** ** **

13 5.00 1 88.00 Æ 2.95 2.00 Æ 1.76 52.40 Æ 13.89

9: lowest dose which inhibits MAO-A activity given in bold.

Signiﬁcance of combination (tetrabenazine + rasagiline) vs. tetrabenazine (ANOVA): p < 0.05.

Signiﬁcance of combination (tetrabenazine + rasagiline) vs. tetrabenazine (ANOVA): p < 0.001.

theoretical possibility. Nevertheless, there is no doubt that both J- progress in therapy exactly for the reason that this compound is in

508 and rasagiline are devoid of a signiﬁcant enhancer effect. the therapeutic dose range devoid of any type of hitherto known

sympathomimetic properties. (À)-Deprenyl is not only free of the

Discussion classical releasing property, but it is even antagonizing the

releasing effect of the amphetamines. In striking contrast, Speizer

The development of (À)-1-phenyl-2-propylaminopentane, (À)- et al. [28] showed that rasagiline potentiated amphetamine-

PPAP, the (À)-deprenyl analog free of the MAO-B inhibitory induced stereotypy whereas selegiline was ineffective.

potency, furnished direct evidence that the enhanced dopaminer- (À)-Deprenyl is a CAE substance. Experimental and clinical

gic activity following the administration of (À)-deprenyl was experiences with (À)-deprenyl are in harmony with Knoll’s

unrelated to the inhibition of MAO-B [23]. The availability of HPLC concept that, except the levodopa-sparing effect in Parkinson’s

to measure catecholamines in physiological quantities allowed for disease, the beneﬁcial therapeutic effects of selegiline are

a new approach. primarily related to enhanced activity of the catecholaminergic

We treated rats with 0.01, 0.025, 0.05, 0.1 and 0.25 mg/kg (À)- neurons in the brain stem. It is worth mentioning here that as

deprenyl, respectively, once daily for 21 days, isolated the discrete Series No. 7 in Table 4 shows the 0.25 mg/kg (À)-deprenyl is the

rat brain regions 24 h after the last injection, and measured the peak dose with the non-speciﬁc enhancer effect and at the same

release of dopamine from the striatum, substantia nigra and time also the optimum dose which inhibits MAO-B activity

tuberculum olfactorium. The amount of dopamine released from selectively. This dose of (À)-deprenyl is equivalent with the 10 mg

these isolated regions clariﬁed that the dopaminergic neurons daily dose used in human therapy. This means that the usually

worked on a signiﬁcantly higher activity level even in rats treated used therapeutic dose of (À)-deprenyl not only inhibits MAO-B

with the lowest, 0.01 mg/kg dose of (À)-deprenyl. This was the ﬁrst activity but also exerts its non-speciﬁc enhancer effect. That (À)-

unequivocal experimental evidence for the operation of a deprenyl-treatment keeps the catecholaminergic neurons on a

previously unknown CAE mechanism in these brain stem neurons higher activity level and maintenance on a low daily dose of (À)-

[24]. deprenyl slows the aging related decline of the catecholaminergic

Further studies clariﬁed that PEA, the parent compound of (À)- system in the brain and prolongs life is now ﬁrmly established by

deprenyl, is primarily an endogenous CAE substance. Since PEA series of experimental studies [14]. Rasagiline is devoid of a

releases in higher concentrations catecholamines from their intra- signiﬁcant CAE effect; thus it cannot be a substitute for (À)-

neuronal stores, its enhancer effect remained undetectable. deprenyl in therapy.

Amphetamine and methamphetamine, PEA derivatives with a The only common property of (À)-deprenyl and rasagiline is

long lasting effect, share with their parent compound the same their ability to selectively block MAO-B activity. Since (À)-

releasing property [11,12,25,26]. (À)-Deprenyl was the ﬁrst PEA/ deprenyl, in contrast to other MAO-B inhibitors, did not potentiate

methamphetamine derivative that maintained the enhancer effect the hypertensive effect of either tyramine or levodopa, the

of its parent compounds but completely lost the releasing introduction of (À)-deprenyl into the therapy of Parkinson disease

property. Since the enhancer effect was not covered up by the signiﬁed a real progress. In contrast to the world-wide used various

release of catecholamines, (À)-deprenyl enabled the discovery of selegiline preparations, only the prescribing information for

the enhancer regulation in the catecholaminergic neurons. rasagiline was constrained to warn the so-called cheese effect

According to Glezer and Finberg [27] rasagiline is superior over and recommend that foods high in tyramine be avoided (see:

(À)-deprenyl for the following two reasons: ‘The selective Azilect package insert).

monoamine oxidase-B inhibitor selegiline [(À)-deprenyl] causes Knoll, who in the 1960s developed (À)-deprenyl, later studied

sympathomimetic effects and is metabolized to (À)-methamphet- also aminoindanes and demonstrated more than 30 years ago that

amine and (À)-amphetamine. The new monoamine oxidase-B J-508, the parent compound of rasagiline was the most potent

inhibitor, rasagiline, is devoid of sympathomimetic effects and is MAO-B inhibitor among the compounds investigated [20, Table 2].

metabolized to (+)-1-aminoindane.’ Because J-508, in contrast to (À)-deprenyl, potentiated the

True that the hitherto known sympathomimetic substances, releasing effect of tyramine [20, Fig. 3], he did not further follow

like the amphetamines, are of restricted therapeutic value because the J-508 line of his research. In contrast to (À)-deprenyl, rasagiline

of their serious side effects. (À)-Deprenyl, however, represents a increases IR signiﬁcantly in a dose of 5 mg/kg. This is the most

458 I. Miklya / Pharmacological Reports 66 (2014) 453–458

[6] Parkinson Study Group. Effect of (À)deprenyl on the progression disability in

sensitive detection of hypermotility due to a slight but functionally

early Parkinson’s disease. N Engl J Med 1989;321:1364–71.

signiﬁcant continuous release of dopamine from their intra-

[7] Tetrud JW, Langston JW. The effect of (À)deprenyl (selegiline) on the natural

neuronal stores. history of Parkinson’s disease. Science 1989;245:519–22.

[8] Parkinson Study Group. Impact of deprenyl and tocopherol treatment of

The claim that rasagiline is superior over (À)-deprenyl because

Parkinson’s disease in DATATOP patients requiring levodopa. Ann Neurol

of the lack of amphetamine metabolites is in fact entirely without 1996;39:37–45.

foundation. An early study furnished evidence that in (À)-deprenyl [9] Knoll J. (À)Deprenyl (selegiline) a catecholaminergic activity enhancer (CAE)

substance acting in the brain. Pharmacol Toxicol 1998;82:57–66.

treated rats no sign of amphetamine-like sympathomimetic effects

[10] Knoll J. Enhancer regulation/endogenous and synthetic enhancer compounds:

can be detected [29]. Because (À)-deprenyl (1 mg daily) slows the

a neurochemical concept of the innate and acquired drives. Neurochem Res

age-related decline of the nigrostriatal dopaminergic neurons in 2003;28:1187–209.

the brain stem, the drug is now widely used as a prophylactic anti- [11] Knoll J, Miklya I, Knoll B, Marko´ R, Kelemen K. (À)Deprenyl and (À)1-phenyl-2-

propylaminopentane, (À)PPAP, act primarily as potent stimulants of action

aging compound. Deprenyl solutions for anti-aging medication, at

TM potential-transmitter release coupling in the catecholaminergic neurons. Life

present Dep-Pro (1 drop = 1 mg), are in circulation since the end

Sci 1996;58:817–27.

of the last century. Because of its unusual safeness (À)-deprenyl [12] Knoll J, Knoll B, Miklya I. High performing rats are more sensitive toward

catecholaminergic activity enhancer (CAE) compounds than their low per-

belongs to the so-called smart drugs.

forming peers. Life Sci 1996;58:945–52.

Otherwise, Zydis Selegiline (Zelapar) an orally disintegrating

[13] Knoll J, Miklya I, Knoll B. Stimulation of the catecholaminergic and serotonin-

tablet form of selegiline hydrochloride is by now available. Buccal ergic neurons in the rat brain by R-(À)-1-(benzofuran-2-yl)-2-propylamino-

pentane, (À)-BPAP. Life Sci 2002;71:2137–44.

absorption eliminates ﬁrst pass metabolism of the drug by the

[14] Knoll J. How selegiline ((À)-deprenyl) slows brain aging. Bentham Science

liver, allowing use of a substantially reduced dose and resulting in

Publishers e-Books; 2012.

marked reduction in (À)-methamphetamine and (À)-amphet- [15] Miklya I, Knoll B, Knoll J. A pharmacological analysis elucidating why, in

contrast to (À)-deprenyl (selegiline) a-tocopherol was ineffective in the

amine metabolites compared with the swallowed form [30].

DATATOP study. Life Sci 2003;72:2641–8.

A remarkable difference between (À)-deprenyl and rasagiline

[16] Finberg JP, Lamensdorf I, Weinstock M, Schwart M, Youdim MB. Pharmacology

was shown in the hippocampus of mice treated with DSP-4, the of rasagiline (N-propargyl-1R-aminoindan). Adv Neurol 1999;80:495–9.

[17] Parkinson Study Group. A controlled trial of rasagiline in early Parkinson

noradrenergic neurotoxin which depletes norepinephrine. A single

disease: the TEMPO study. Arch Neurol 2002;59:1937–43.

intraperitoneal dose of (À)-deprenyl markedly reduced the

[18] Miklya I, Knoll J. Analysis of the effect of (À)-BPAP, a selective enhancer of the

norepinephrine depleting effect of the toxin; rasagiline was impulse propagation mediated release of catecholamines and serotonin in the

ineffective [31]. brain. Life Sci 2003;72:2915–21.

[19] Knoll J, Yoneda F, Knoll B, Ohde H, Miklya I. (À)l-(Benzofuran-2-yl)-2-propy-

The clinical trial with rasagiline, performed by the Parkinson

laminopentane, [(À)BPAP], a selective enhancer of the impulse propagation

Study Group, revealed that unlike the early selegiline trials,

mediated release of catecholamines and serotonin in the brain. Br J Pharmacol

rasagiline failed to demonstrate a decreased need for levodopa 1999;128:1723–32.

[20] Knoll J. The pharmacology of selective irreversible monoamine oxidase

[17]. Even the results of a couple of recent studies [32–34] led to

inhibitors. In: Seiler N, Jung MJ, Koch-Weser J, editors. Enzyme-activated

the conclusion that ‘‘based on current evidence, rasagiline cannot

irreversible inhibitors. Amsterdam/New York/Oxford: Elsevier/North Holland

be said to deﬁnitely have a disease-modifying effect’’ [35]. Table 4 Biomedical Press; 1978. p. 253–69.

[21] Knoll J. The possible mechanism of action of (À)deprenyl in Parkinson’s

(Series No. 7) shows that the usually used dose of (À)-deprenyl

disease. J Neural Transm 1978;43:177–98.

(0.25 mg/kg) which blocks MAO-B activity is also the peak dose

[22] Knoll J, Ecsery Z, Magyar K, Sa´tory E´ . Novel (À)deprenyl-derived selective

with the non-speciﬁc enhancer effect. Knoll’s conclusion that the inhibitors of B-type monoamine oxidase. The relation of structure to their

action. Biochem Pharmacol 1978;27:1739–47.

CAE effect is responsible for the disease modifying effect of (À)-

[23] Knoll J, Knoll B, To¨ro¨k Z, Tima´r J, Yasar S. The pharmacology of 1-phenyl-2-

deprenyl in PD [14] is supported by the fact that both a-tocopherol

propylaminopentane (PPAP), a deprenyl-derived new spectrum psychostimu-

[15] and rasagiline are devoid of the CAE effect and both drugs lant. Arch Int Pharmacodyn Ther 1992;316:5–29.

[24] Knoll J, Miklya I. Multiple, small dose administration of ( )deprenyl enhances

failed in untreated patients with PD to signiﬁcantly delay the need À

catecholaminergic activity and diminishes serotoninergic activity in the brain

for levodopa therapy.

and these effects are unrelated to MAO-B inhibition. Arch Int Pharmacodyn

Ther 1994;328:1–15.

[25] Knoll J, Miklya I. Enhanced catecholaminergic and serotoninergic activity in rat

Conﬂict of interest

brain from weaning to sexual maturity. Rationale for prophylactic (À)deprenyl

(selegiline) medication. Life Sci 1995;56:611–20.

There is no conﬂict of interest for the author. [26] Knoll J, Miklya I, Knoll B, Marko´ R, Ra´cz D. Phenylethylamine and tyramine are

mixed-acting sympathomimetic amines in the brain. Life Sci 1996;58:2101–14.

[27] Glezer S, Finberg JP. Pharmacological comparison between the actions of

Funding methamphetamine and 1-aminoindan stereoisomers on sympathetic nervous

function in rat vas defferens. Eur J Pharmacol 2003;472:173–7.

[28] Speizer Z, Levy R, Cohen S. Effects of N-propargyl-1-1-aminoindan (rasagi-

This study was supported by the Scientiﬁc Health Council of the

line) in models of motor and cognition disorders. J Neural Transm

Hungarian Ministry of Health (ETT 606/2006-2008; 101/2009- 1998;52(Suppl.):287–300.

2011). [29] Tima´r J, Knoll B, Knoll J. (À)Deprenyl (Selegiline) is devoid of amphetamine-

like behavioural effects in rats. Acta Physiol Hung 1992;79:131–7.

[30] Clarke A, Brewer F, Johnson ES, Mallard N, Hartig F, Taylor S, et al. A new

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