-Induced Behavioral Alterations Following Repeated Administration of Methamphetamine

Yasumitsu YAMANAKA, Ritsuko TAKANO and Toru EGASHIRA

Department of Pharmacology, Medical College of Oita, Hazama-cho, Oita 879-56, Japan

Accepted February 17, 1986

Abstract-Repeated administration of a large dose of methamphetamine (MA) (25 mg/kg, i.p. twice daily for 4 days) to mice enhanced locomotor activity and decreased stereotyped behavior following a subsequent injection of MA. Simul taneous determinations of catecholamines revealed a depletion of brain dopamine. The moderate doses of haloperidol significantly enhanced MA-induced locomotor activity in mice. A significant enhancement of MA-induced locomotor activity was observed in the rats pretreated with 6-hydroxydopamine into the striatum, and this effect correlated negatively with the striatal dopamine level. These results suggest that hypofunction of striatal dopaminergic neuron systems induced by repeated administration of MA may be one of possible mechanisms of the enhance ment of MA-induced locomotor activity due to the decrease of stereotyped behavior.

Repeated administration of MA on the sensitivity to the behavioral has been shown to alter sensitivity to sub effects of subsequent doses of MA in the sequent doses of amphetamines. These al mouse and the effects of several neuro terations produced by repeated administration pharmacological drugs on MA-induced of amphetamines, however, depend to a behavioral effects in the mouse or rat. large extent on the frequency of adminis tration, the dose, route of administration and Materials and Methods the behavior in question. Animals: Male ddY strain mice weighing Because psychosis is most initially approx. 20 g and male Wistar strain frequently observed in addicts who have rats weighing initially approx. 180 g were consumed enormous amounts of the drug used. over prolonged periods (1), development of Drugs: Methamphetamine hydrochloride this psychosis may require a more sustained (MA) was obtained from Dainippon Seiyaku level of amphetamine intoxication. In this Co. 6-Hydroxydopamine hydrochloride regard, although many methods have been (60HDA) was purchased from Sigma reported to sustain the level of the in Chemical Co. Haloperidol (Serenase Injec toxication, a dosage schedule of 25 mg/kg of tion) and levomepromazine hydrochloride methamphetamine (MA) twice daily for 4 (Levotomin Injection) were obtained from days to the mouse was chosen, which may Dainippon Seiyaku Co. and Yoshitomi be selectively neurotoxic on dopamine Seiyaku Co., respectively. terminals in the rat striatum, as suggested by Repeated administration of MA: Mice Wagner et al. (2). were pretreated with MA (25 mg/kg, i.p.) or Behavioral effects and dopaminergic saline twice daily at 9:00 and 17:00 for 4 mechanisms of amphetamines in the mouse consecutive days. have been demonstrated to be similar to Behavioral rating: The behavior of each those in the rat (3, 4). Therefore, we herein mouse was rated by the method of Peachey report the effects of this dosage schedule of et al. (3) over a 4 hr period following the i.p. injections of the challenge doses of 2.5, Pellegrino (6). After 3 weeks, the rats were 5 and 10 mg/kg of MA 18 hr after the last injected with the challenge doses of 2.5 and injection. Mice were placed in individual 10 mg/kg of MA, and activity was recorded. activity cages 1 hr before MA treatment. The The striatal DA levels were then determined following 2 behavioral parameters were 1 week after the MA injection. quantitated: activity (locomotor activity in any direction) and stereotyped behavior Results (gnawing, licking or sniffing). Ten ratings Changes in MA sensitivity following were made over a 90-sec period at exactly repeated administration of MA: Figure 1 10-sec intervals. Each rating consisted of shows the time course of behavioral effects noting the presence or absence of each type of MA in saline control mice and MA of behavior using a score of 1 or 0, respec treated mice. The effects of MA in the saline tively. The maximum possible rating score control mice were almost identical to those for each parameter was 10. described in the previous paper (5). Briefly, Measurement of activity: The mouse was 2.5 mg/kg of MA markedly enhanced individually placed in an activity cage, and locomotor activity over 2 hr, while stereo activity was recorded for 5 min beginning typed behavior was slightly observed. The 1 min after placing the animal in the activity behavioral effect of 5.0 mg/kg of MA was cage each hour after drug treatment using of the mixed type consisting of increased an Automex II 2SD. locomotor activity and stereotyped behavior. Catecholamine assay: Brain NE and DA At 10 mg/kg of MA, locomotor activity concentrations were determined fluorome markedly increased at the first 15 min, trically after high performance liquid chro gradually diminished till 1 hr, and then matography. The detailed procedures were increased from 2 hr. Stereotyped behavior described in the previous paper (5). reached at a maximum at 30 min, lasted for Single administration of haloperidol or 2 hr and then gradually subsided. Ac levomepromazine: At 30 min after adminis cordingly, the characteristic behavioral effects tration of 0.05, 0.1 and 0.2 mg/kg of of MA were enhanced locomotor activity at haloperidol or 0.2, 0.5 and 1 mg/kg of 2.5 mg/kg of MA and stereotyped behavior levomepromazine to drug naive mice, the at 10 mg/kg of MA. animals were given a challenge dose of 10 The time course changes in the behaviors mg/kg of MA, and activity was recorded after administration of subsequent doses of over 3 hr. 2.5 and 5 mg/kg of MA were similar between Repeated administration of haloperidol or MA-treated and saline control mice, while levomepromazine: Drug naive mice were the rating scores of locomotor activity in the given 1 mg/kg of haloperidol or 5 mg/kg of MA-treated mice tended to decline earlier levomepromazine twice daily (9:00 and than those in the saline control mice. In the 17:00) for 6 consecutive days. After 2 day case of 10 mg/kg of MA, however, a , the mice were given the characteristic change in the behavior was challenge doses of 2.5 and 10 mg/kg of MA, observed in the MA-treated mice. Locomotor and activity was recorded over 4 hr. activity increased at the first 15 min with Striatal injection of 6OHDA in the rat: the peak points of 5.6±1.7, diminished to Under pentobarbital anesthesia (40 mg/kg, 2.9+1.8 points at 30 min and then gradually i.p.), each rat was positioned in a stereotaxic increased, reaching 8.9±0.7 points at 2 hr. apparatus 30 min after pretreatment of 50 At that period, the rating score of locomotor mg/kg of pargyline, and 8 ,ug of 6OHDA in activity in the saline control mice was still 2 ,el vehicle was infused bilaterally into the 0 points. The rating score of stereotyped region of the corpus striatum over a 1-min behavior in the MA-treated mice reached a period in each region. Sham-operated rats maximum of 8.6±1.0 points at 30 min and were injected similarly with vehicle. The gradually decreased to 2.0±1.5 at 2 hr. stereotaxic coordinates were A: 8.0, L: 2.5 During this period, the maximum points of and V: +1.2, according to the atlas of stereotyped behavior in the saline control mice was still observed. Accordingly, the early subsidence of stereotyped behavior. marked increase in locomotor activity at 2 hr Figure 2 shows the activity counts in the MA-treated mice seemed to be due to measured by an Automex II 2SD. At 2.5 mg/

Fig. 1. MA-induced behavioral effects in mice following repeated administration of MA. 0-0 saline control mice, 0 MA-treated mice. Mice were placed in individual cages, and MA-induced behaviors were scored as described in Methods. Each point represents the mean±S.E. of 7 animals. MA was given in a dose of 25 mg/kg twice daily for 4 consecutive days. Subsequent doses of MA were 2.5, 5 and 10 mg/kg.

Fig. 2. MA-induced activity in mice following repeated administration of MA. A saline to naive mice, 9 MA to saline control mice, 0----0 MA to MA-treated mice. A mouse was placed in an activity cage, and activity was recorded using an Automex II 2SD as described in Methods. Each point represents the mean±S.E. of 8 animals. MA was given in a dose of 25 mg/kg twice daily for 4 consecutive days. Subsequent doses of MA were 2.5, 5 and 10 mg/kg. *Significantly different from the control at P<0.01. kg of MA, activity in the saline control mice was enhanced at 1 and 2 hr and returned to normal at 3 hr. This time course is almost identical to the results estimated by the rating system. At 5 and 10 mg/kg of MA, however, the activity counts did not always coincide with the results estimated by the rating system, i.e., activity counts were inconsistently recorded even when scores of locomotor activity and stereotyped behavior was 0 and 10 points, respectively. These counts, however, were not significantly different from the counts at zero time. Therefore, activity counts seemed to reflect mainly locomotor activity. Following re peated administration of MA, activity was markedly enhanced at any challenge dose of MA. Significant differences in activity between the MA-treated group and the saline control group were demonstrated at 1 and 2 hr in doses of 5 and 10 mg/kg of MA (P<0.01), although there was no significant difference at 2.5 mg/kg of MA. Fig. 3. MA induced activity in mice pretreated Effects of MA on NE and DA levels with haloperidol or levomepromazine. haloperidol: following repeated administration of MA: 0 control, O 0.05 mg/kg, A 0.1 The time course of the steady-state levels of mg/kg, L -A 0.2 mg/kg; levomepromazine: NE and DA over 3 hr is shown in Table 1. 40 control, 0 0.2 mg/kg, A 0.5 Initial levels of NE were identical between mg/kg, A -Q 1 mg/kg. A mouse was placed in an the saline control mice and the MA-treated activity cage, and activity was recorded using an mice. There was no significant difference in Automex II 2SD as described in Methods. MA was the time course changes in the NE level given in a dose of 10 mg/kg. Each point represents the mean±S.E. of 8 animals. *Significantly different between the saline control mice and the MA from the control at P<0.01. treated mice, although 5 and 10 mg/kg of MA tended to deplete NE in both groups. The initial level of DA in the MA-treated did not enhance MA-induced activity. When mice was significantly lower than that in the levomepromazine in doses of 0.5 and 1 mg/ saline control mice. The time course of the kg was given to mice, the early stage of DA levels in the MA-treated mice after increase in MA-induced activity at 30 min injection of 2.5, 5 and 10 mg/kg of MA was was inhibited. not significantly different from that in the Effects of repeated administration of saline control mice. haloperidol or levomepromazine on MA Effects of single administration of induced activity: When mice were repeatedly haloperidol or levomepromazine on MA given haloperidol, an enhancement of induced activity: Activity induced by 10 mg/ activity induced by 2.5 mg/kg of MA was kg of MA was recorded over 3 hr in the mice observed, and locomotor activity induced by pretreated with haloperidol or levomepro 10 mg/kg of MA was decreased because of mazine. The results are shown in Fig. 3. possible enhanced stereotypy. Repeated When haloperidol was given to mice in administration of levomepromazine, however, doses of 0.05 and 0.1 mg/kg, MA-induced did not alter activity induced by 2.5 or 10 activity was significantly enhanced as com mg/kg of MA (Fig. 4). pared with that in the saline control mice. Effects of striatal injections of 6OHDA on Haloperidol in a dose of 0.2 mg/kg, however, MA-induced activity: Eight icg of 6OHDA Behavioral Alterations by Repeated Methamphetamine Fig. 4. MA-induced activity in mice following Fig. 5. MA-induced activity in rats pretreated with repeated administration of haloperidol or levome bilateral striatal injections of 60HDA. *-0 promazine. 40-0 control, O haloperidol, control rat, O 60H DA-treated rat. A rat was A levomepromazine. A mouse was placed in an activity cage, and activity was recorded using an placed in an activity cage, and activity was recorded using an Automex II 2SD as described in Methods. Automex II 2SD as described in Methods. MA was given in doses of 2.5 and 10 mg/kg. Each Haloperidol and levomepromazine were given in point represents the mean±S.E. of 8 animals. doses of 1 and 5 mg/kg twice daily for 6 consecutive *Significantly different from the control at P<0 .01. days, respectively. MA was given in doses of 2.5 and 10 mg/kg. Each point represents the mean±S.E. of 8 animals. *Significantly different from the control at P<0.05.

injected bilaterally into the striatum of the rats resulted in approx. 50% depletion of endogenous DA; i.e., striatal DA levels were 3.52±0.21 /tg/g in the vehicle control rats and 1.84±0.27 iig/g in the 60HDA-treated rats. Locomotor activity induced by 2.5 mg/ kg of MA i n the 60 H DA-treated rats was similar to that in the vehicle control rats. However, locomotor activity induced by 10 mg/kg of MA in the 60HDA-treated rats was significantly enhanced at 30 min as compared with that in the vehicle control rats (P<0.01 ), as shown in Fig. 5. Regression analysis revealed the negative correlation between striatal DA levels and counts of activity induced by 10 mg/kg of MA in the 60HDA treated rats (Fig. 6). Fig. 6. Regression analysis between striatal DA levels and counts of activity induced by 10 mg/kg of Discussion MA in the 60HDA-treated rats. The present results demonstrated that repeated administration of a large dose of MA former is a potent amphetamine antagonist (25 mg/kg, i.p., twice daily for 4 days) to and the latter has a potent sedative effect and mice enhanced the early stage of locomotor mild amphetamine antagonism (15). The activity and decreased the stereotyped moderate doses of haloperidol significantly behavior following a subsequent injection of enhanced locomotor activity induced by 10 MA. Simultaneous determinations of cate mg/kg of MA, possibly because stereotypy cholamines revealed a depletion of brain may be effectively inhibited. A high dose did dopamine, as reported by Wagner et al. (2) not enhance locomotor activity, possibly in the rat. because most of the dopaminergic receptors Stimulation of locomotor activity and were inhibited. Chronic neuroleptic treatment stereotyped behavior by amphetamine is increased sensitivity to dopaminergic agents proposed to be associated with dopaminergic (16-18). Moreover, single neuroleptic nerve activity of the nucleus accumbens and treatment has been reported to increase the striatum, respectively (7). Several postsynaptic sensitivity (19). After repeated authors have reported that repeated adminis administration of haloperidol to mice, tration of moderate amounts of amphetamine locomotor activity induced by 2.5 mg/kg of or MA produced enhancement of behavioral MA was increased, and locomotor activity effects induced by these drugs following the induced by 10 mg/kg of MA was decreased subsequent administration, i.e., reverse because of possible enhanced stereotypy. tolerance (8-12). However, it is suggested When eight icg of 60 H DA was injected that this effect is not mediated by alteration bilaterally into the striatum of the rat, in the sensitivity of pre or post-synaptic locomotor activity induced by 10 mg/kg of dopaminergic receptors in the striatum (13). MA was significantly enhanced, and this On the other hand, an interesting report effect correlated negatively with striatal DA has appeared (9). Rats administered amphe levels. tamine in a continuous regime using silicone These results may indicate that locomotor pellets were hyperactive when initially tested activity was enhanced if dopaminergic with amphetamine and subsensitive to neuron systems in the nucleus accumbens apomorphine. Following repeated daily in were intact and those in the striatum were jections of an amount of amphetamine affected either pre or post-synaptically, equivalent to that released by a pellet, because enhanced locomotor activity is however, rats showed enhanced motor masked by predominant stereotypy. Although stereotypies when injected with amphe we demonstrated the depletion of dopamine tamine. It is also demonstrated that con only in whole mouse brains following re tinuous treatment with amphetamine can peated administration of MA, Morgan and induce long-lasting structural and bio Gibb (20) demonstrated that tyrosine chemical alterations in dopaminergic termi hydroxylase activity and dopamine levels nals in the caudate nucleus (14). were significantly decreased in the neo Under the present experimental conditions, striatum but not altered in the nucleus ac we demonstrated the production of dopamine cumbens after 1 5 mg/kg of MA were admin depletion in whole mouse brains, and istered to the rat every 6 hr for 5 doses. Wagner et al. (2) demonstrated the production Lucot et al. (21) reported that treatment of of long-term decreases in dopamine levels rats with 100 mg/kg/day of MA for 4 days and decrease in the number of dopamine produced long-lasting depletion of brain uptake sites in the rat striatum. From these levels of dopamine. They also reported that observations, we hypothesized that hypo this treatment attenuated the ability of MA functions of striatal dopaminergic neuron and apomorphine to produce increases in systems might produce the enhanced locomotor activity, but the mechanisms for locomotor activity and decreased stereo this were obscure. One of the possible mecha typed behavior observed in the present nisms may be the depletion of caudate experiment. We used two neuroleptics, dopamine and the rest of brain dopamine, as haloperidol and levomepromazine; the they reported.

induced behavioral facilitation. J. Pharmacol. Exp. Ther. 221, 650-655 (1982)

innervation of caudate nucleus after continuous amphetamine administration. Science 201, 276 278 (1978)

In conclusion, our results suggest that 11 Segal, D.S., Weinberger, S.B., Cahill, J. and hypofunction of striatal dopaminergic neuron McCunney, S.J.• Multiple daily amphetamine systems induced by repeated administration administration: behavioral and neurochemical of MA may be one of the possible mechanisms alterations. Science 207, 904-907 (1980) for the enhancement of MA-induced 12 Hirabayashi, M. and Alam, M.R.: Enhancing effect of methamphetamine on ambulatory locomotor activity due to the decrease in activity produced by repeated administration in stereotyped behavior. mice. Pharmacol. Biochem. Behav. 15, 925-932 (1981) References 13 Conway, P.G. and Uretsky, N.J.: Role of striatal 1 Griffith, J.D., Cavanaugh, J., Held, J. and Oates, dopaminergic receptors in amphetamine J.A.: : Evaluation of psycho mimetic properties in man. Arch. Gen. Psychiat. 26, 97-100 (1972) 14 Ellison, G., Eison, M.S., Huberman, H.S. and 2 Wagner, G.C., Ricaurte, G.A., Seiden, L.S., Daniel, F.: Long-term changes in dopaminergic Schuster, C.R., Miller, R.J. and Westley, J.: Long-lasting depletions of striatal dopamine and loss of dopamine uptake sites following repeated administration of methamphetamine. Brain Res. 15 Janssen, P.A. and Van Beber, W.F.M.: Preclinical 181, 151-160 (1980) psychopharmacology of neuroleptics. In 3 Peachey, J.E., Rogers, B., Brien, J.F., Maclean, Principles of Psychopharmacology, Second Ed., A. and Rogers, D.: Measurement of acute and Edited by Clerk, W.G. and Del Giudice, J., p. chronic behavioral effects of methamphetamine 279-295, Academic Press, New York (1978) in the mouse. Psychopharmacology 48, 271-275 16 Gianutsos, G., Drawbaugh, R.B., Hynes, M.D. (1976) and Lal, H.: Behavioral evidence for dopaminergic 4 Thornburg, J.E. and Moore, K.E.: The relative supersensitivity after chronic haloperidol. Life importance of dopaminergic and noradrenergic Sci. 14, 887-898 (1974) neuronal systems for the stimulation of locomotor 17 Tarsy, D. and Baldessarini, R.J.: Behavioral activity induced by amphetamine and other drugs. supersensitivity to apomorphine following Neuropharmacology 12, 853-866 (1973) chronic treatment with drugs which interfere 5 Yamanaka, Y., Yamamoto, T. and Egashira, T.: with the synaptic function of catecholamines. Methamphetamine-induced behavioral effects Neuropharmacology 13, 927-940 (1974) and releases of brain catecholamines and brain 18 Von Voigtlander, P.F., Losey, E.G. and concentrations of methamphetamine in mice. Triezenberg, J.: Increased sensitivity to dopami Japan. J. Pharmacol. 33, 33-40 (1983) nergic agents after chronic neuroleptic treat 6 Pellegrino, L.J., Pellegrino, A.S. and Cashman, ment. J. Pharmacol. Exp. Ther. 193, 88-94 A.J.: A Stereotaxic Atlas of the Rat Brain, (1975) Second Ed., Plenum Press, New York (1979) 19 Martres, M.P., Costentin, J., Baudry, M., 7 Kelly, P.H., Seviour, P.W. and Iversen, S.D.: Marcais, H., Protais, P. and Schwartz, J.C : Amphetamine and apomorphine responses in the Long-term changes in the sensitivity of pre and rat following 6-OHDA lesions of the nucleus postsynaptic dopamine receptors in mouse accumbens septi and corpus striatum. Brain Res. striatum evidenced by behavioural and bio 94, 507-522 (1975) chemical studies. Brain Res. 136, 319-337 8 Echols, S.D.: Circling of mice bearing unilateral (1977) striatal lesions: development of increased 20 Morgan, M.E. and Gibb, J.W.: Short-term and response to D-amphetamine. Life Sci. 21, 563 long-term effects of methamphetamine on 568 (1977) biogenic amine metabolism in extra-striatal 9 Nelson, L.R. and Ellison, G.: Enhanced stereo dopaminergic nuclei. Neuropharmacology 19, typies after repeated injections but not con 989-995 (1980) tinuous amphetamines. Neuropharmacology 17, 21 Lucot, J.B., Wagner, G.C., Schuster, C.R. and 1081-1084 (1978) Seiden, L.S.: The effects of dopaminergic agents 10 Echols, S.D.: Reverse tolerance to amphetamine on the locomotor activity of rats after high doses of mice bearing unilateral striatal lesions: effect of methylamphetamine. Pharmacol. Biochem. upon the circling response to apomorphine. Life Behav. 13, 409-413 (1980) Sci. 24, 691-696 (1979)