South African Journal of Botany 94 (2014) 33–39

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South African Journal of Botany

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Long-term cardiovascular autonomic responses to aqueous ethanolic extract of in early maternally separated BALB/c mice

William Pote a,⁎, Dexter Tagwireyi b, Herbert M. Chinyanga c, Colin Musara a, Davies M. Pfukenyi d, Pilani Nkomozepi e, Louis L. Gadaga b, George Nyandoro a, Jephat Chifamba c a Preclinical Veterinary Studies Department, Faculty of Veterinary Science, University of Zimbabwe, Zimbabwe b Drug and Toxicology Information Service, School of Pharmacy, College of Health Sciences, University of Zimbabwe, Zimbabwe c Department of Physiology, College of Health Sciences, University of Zimbabwe, Zimbabwe d Clinical Veterinary Studies, Faculty of Veterinary Science, University of Zimbabwe, Zimbabwe e Division of Neuroscience, University of Witwatersrand, South Africa article info abstract

Article history: Background: Boophone disticha is commonly used in southern Africa for the management of mental-related Received 10 December 2013 illnesses. Recently, it was shown to reduce blood pressure (BP) in maternally separated mice immediately Received in revised form 16 April 2014 after withdrawal of treatment. However, the long-term cardiovascular effects and the underlying mechanisms Accepted 22 April 2014 are still illusive. Based on the reputed traditional use of the for anxiety and stress-related disorders, Available online xxxx the aqueous-ethanolic extract of B. disticha was screened for its long-term effects on the cardiovascular and autonomic responses to repeated acute stressors in adult early maternally separated BALB/c mice. Edited by JJ Nair Methods: Five groups (n = 6 each) of adult BALB/c mice subjected to early maternal separation (MS) were given Keywords: six daily oral doses of vehicle (normal saline); low, medium and high doses of B. disticha (10, 25 and 40 mg/kg B. disticha body weight, respectively); and 1 mg/kg body weight diazepam during adulthood. The control (un-separated) Antihypertensive activity group (n = 6) received vehicle treatment. Cardiovascular parameters (BP and heart rate (HR)) were recorded Autonomic response using non-invasive tail-cuff methods on post-treatment days (PTDs) 9 and 30 to compare short-term and Cardiovascular comorbid disorders long-term effects of the plant extract, respectively. Autonomic responses were measured by estimating BP Anxiety disorders variability (BPV) and HR variability (HRV). Results: Early maternal separation significantly increased systolic BP (SBP), and decreased HR on PTD9 while raising BPV on PTD30 when compared to control un-separated mice (p b 0.05). B. disticha at low dose significant- ly reduced short-term SBP and mean arterial pressure (MAP), while medium dose reduced long-term diastolic BP (DBP) and MAP in maternally separated mice when compared to vehicle and diazepam (p b 0.05). High dose significantly decreased SBP and MAP at both occasions (p b 0.05). Conclusions: The current results have led to the identification of long-term antihypertensive-like activity of the aqueous ethanolic extract of B. disticha which was found to last for several weeks after withdrawal of treatment. © 2014 SAAB. Published by Elsevier B.V. All rights reserved.

1. Introduction It is used for the treatment of several mental-related conditions such as epilepsy, seizures, psychosis, anxiety, depression and cognitive disor- Boophone disticha (L.f.) Herb. () known as ‘sore-eye ders (De Smet, 1996; Gelfand and Mitchell, 1952; Gelfand et al., 1985; flower’ (‘munzepete’ in Shona and ‘ingcotho’ in IsiNdebele), is used for Gomes et al., 2009; Hutchings et al., 1996; Nair and Van Staden, 2014; medicinal purposes among the indigenous people of southern Africa. Stafford et al., 2008; Steenkamp, 2005). Although, the mechanism un- derlying the effects of the plant is largely unknown, in vivo studies done on the crude extract showed that the plant has potential antide- Abbreviations: AMS, acute mixing stress; BP, blood pressure; BPV, blood pressure var- iability; BW, body weight; DBP, diastolic blood pressure; DZP, diazepam; HDBD, high dose pressant (Chingombe et al., 2010; Pedersen et al., 2008), anxiolytic B. disticha; HR, heart rate; HRV, heart rate variability; LDBD, low dose Boophone disticha; (Chuma et al., 2010; Musarira et al., 2011), nootropic (Gadaga, 2012) MAP, mean arterial pressure; MDBD, medium dose B. disticha; MS, maternal separation; and antihypertensive (Pote et al., 2013) activities in animal models. PND, postnatal day; PTD, post-treatment day; SBP, systolic blood pressure; Veh, vehicle. Anxiety and depression disorders are the most prevalent psychiatric ⁎ Corresponding author at: PO Box MP167, Mount Pleasant, Harare, Zimbabwe. conditions. These conditions are commonly undertreated because they Tel.: +263 773234621, +263 736566176; fax: +263 4333678. E-mail addresses: [email protected], [email protected], occur along with other mental or physical illnesses, mostly comorbid [email protected] (W. Pote). cardiovascular disorders, that mask their symptoms causing socio-

http://dx.doi.org/10.1016/j.sajb.2014.04.012 0254-6299/© 2014 SAAB. Published by Elsevier B.V. All rights reserved. 34 W. Pote et al. / South African Journal of Botany 94 (2014) 33–39 economic burden and personal distress (Belzung and Griebel, 2001; assigned to five treatment groups: B, C, D, E, and F (n = 6 each; with Sarris and Kavanagh, 2009). Current treatments are less than satisfacto- 3 males and 3 females housed in separate cages, Fig. 1). Groups A ry; for example, a considerable proportion of patients are non- (control + Veh) and B (MS + Veh) were given a vehicle (normal sa- responsive to first-line treatment, the onset of action is delayed and line). Groups C (MS + LDBD), D (MS + MDBD) and E (MS + HDBD) re- the drugs can induce side effects which significantly impair compliance ceived low (10 mg/kg body weight (BW)), medium (25 mg/kg BW) (Sarris and Kavanagh, 2009). In addition, these medications are benefi- and high (40 mg/kg BW) doses of B. disticha, respectively; while cial to only 65% of the patients; hence, most people with severe depres- Group F (MS + DZP) received 1 mg/kg BW diazepam (Fig. 1). sion and anxiety attacks use complementary and alternative medicine to treat these conditions (Sarris and Kavanagh, 2009). Since anxiety significantly increases morbidity and mortality in heart diseases 2.3.1. Cardiovascular responses to acute mixing stress (Belzung and Griebel, 2001), successful treatment for psychiatric disor- The present study repeated the procedures of acute mixing stress ders should aim to correct the abnormalities of central cardiovascular (AMS) and restraint stress described recently by Pote et al. (2013) on autonomic regulation (Cohen and Benjamin, 2006; Depino and Gross, post-treatment day 9 (PTD9) and PTD30 (i.e. PND85 and PND106, re- 2007; Igosheva et al., 2004; Volkmar et al., 2005). spectively). Blood pressure (systolic blood pressure (SBP), diastolic BP Most recently, a study done by Pote et al. (2013) found that (DBP), mean arterial pressure (MAP)) and heart rate (HR) were record- B. disticha extract (10 to 40 mg/kg body weight (BW)), significantly ed for 5 min between 09.00 and 15.00 h on PTD9 (short-term response) reduced systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure and PTD30 (long-term response). A non-invasive tail-cuff system (MAP) in maternally separated (MS) mice immediately after withdraw- (BIOPAC® System Inc., CA) was used to monitor all the cardiovascular al of treatment. B. disticha may therefore be utilized to develop a drug parameters (Pote et al., 2013). for treatment of comorbid cardiovascular disorders that are frequently associated with anxiety and mood disorders. However, the low re- sponse rate to treatment makes it very difficult to prove on short-term 2.3.2. Autonomic reactivity basis that the plant has anxiolytic, antidepressant or antihypertensive The standard deviation of the MAP (SDMAP) calculated for every seg- efficacy. Therefore, the present study was set to explore the long-term ment (24 s) of the recording period was used as a measure of blood pharmacological effects of the aqueous ethanolic extract of B. disticha pressure variability (BPV) (Igosheva et al., 2004). Standard deviation on blood pressure (BP), heart rate (HR), BP variability (BPV) and HR of heart rate (SDHR) calculated from every heart beat, recorded on the variability (HRV) in a maternal separation animal model of anxiety interval between the SBP and DBP, was used as a measure of heart disorder. rate variability (HRV).

2. Materials and methods 2.4. Statistical analysis The experimental protocols, care and handling of animals used in this study were in accordance with international guidelines (European Data was initially captured with Excel where it was sorted and then Community guidelines, EEC Directive of 1986; 86/609/EEC) on the use exported to statistical package software (SPSS® version 16.0) for further and care of laboratory animals and were approved by the Division of analysis. Comparisons were done on treatment groups using multivari- Veterinary Services, Zimbabwe (Pote et al., 2013). ate multiple comparison analysis and independent Student's t-test. Changes in cardiovascular parameters were calculated by subtracting 2.1. Plant materials, extraction and qualitative analysis of alkaloids values recorded on PTD9 from PTD30 readings and the mean changes were analyzed using independent t-test and one-way ANOVA with mul- of B. disticha were harvested, authenticated, and dried and the tiple comparisons across all test groups. The normal mice (Group A; aqueous ethanolic (70% v/v) extract was prepared as described previ- Control + Veh) was first compared to Group B (MS + Veh; Fig. 1)on ously (Gadaga et al., 2011; Pote et al., 2013). Chromatographic analysis PTD9 and PTD30 to determine how habituation to repeated acute (Zulu et al., 2011)confirmed the presence of isoquinoline alkaloids mixing stress would affect the cardiovascular and autonomic reactivity. reported in previous studies (Adewusi et al., 2012; Cheesman et al., MS mice treated with three doses of B. disticha extract (low, medium 2012; Hauth and Stauffacher, 1961; Neergaard et al., 2009; Sandager and high doses: Groups C, D and E), were compared to the vehicle et al., 2005; Steenkamp, 2005). (Group B) and diazepam (Group F; Fig. 1). Comparisons were also made on normal un-separated mice that received vehicle (Group A) 2.2. Animals and housing conditions and all MS treated mice Groups C–F(Fig. 1)tofind which treat- ment would retain and maintain the animal health towards the Pregnant BALB/c mice, obtained from the Central Veterinary Labora- normal range on PTD9 and PTD30. All data were expressed as mean tory Breeding Unit in The Ministry of Agriculture (Zimbabwe), were difference ± standard error (S.E.) with a significance level of p b 0.05. housed in the Animal Holding facilities at the University of Zimbabwe (UZ) under conditions previously described by Pote et al. (2013). 3. Results 2.3. Experimental protocols MS mice had a significantly higher SBP when compared to control Control pups (un-separated group) were not separated from their mice on PTD9 with a mean difference of 4.6 ± 1.8 millimeter mercury dams during the deprivation period while the treatment pups were (mm Hg, p b 0.02) but this effect was absent on PTD30 (p N 0.05). maternally separated. The procedures for maternal separation (MS) DBP, MAP and changes in BP recorded over the entire test period were were as described earlier by Pote et al. (2013). The study animals comparable between the two groups (p N 0.05) (Fig. 2). When early were weaned, caged, grouped and given treatments from post-natal maternally separated mice were compared to the control, initially on day (PND) 71–76 as reported previously (Pote et al., 2013). Briefly, the PTD9 they exhibited lower HR (mean difference 53.7 ± 16.5 beats per control group (Group A) comprised of six mice (three males and three minute (bpm); p b 0.001), but the difference disappeared on PTD30 females) randomly selected from an un-separated litter. For the (mean difference 11.8 ± 13.9 bpm; p N 0.05). The change in HR treatment groups, 30 mice (15 males and 15 females) were selected over the testing period was non-significantly higher in the former randomly from a maternally separated colony. These were randomly group (p =0.091). W. Pote et al. / South African Journal of Botany 94 (2014) 33–39 35

Fig. 1. A schematic diagram summarizing the study design, protocols and procedures used in this study. PTD, post-treatment day; PND, post-natal day; MS, maternal separation; Veh, vehicle.

3.1. Long-term cardiovascular response to B. disticha treatment in adult MS 3.1.2. Diastolic blood pressure (DBP) mice MS mice treated with either the high or the medium dose of B. disticha had significantly reduced DBP at PTD9 and PTD30, when 3.1.1. Systolic blood pressure (SBP) compared to the vehicle-treated group (mean difference of 8.8 ± At PTD9 (short-term observations), MS mice treated with low and 4.08 mm Hg and 5.6 ± mm Hg, respectively; p b 0.05). However, high doses of B. disticha had significantly lower SBP when compared when compared to MS mice treated with diazepam, only the medium to vehicle treated MS mice (mean differences; 6.28 ± 1.83 mm Hg, dose of B. disticha-treated group had significantly reduced DBP at p b 0.03 and 3.80 ± 1.83 mm Hg, p b 0.05, respectively). However, PTD9 (mean difference of 6.45 ± 4.08 mm Hg, p b 0.03). The dose- only MS animals treated with the low dose of B. disticha had a significant- dependent effect on DBP was exhibited at PTD9 by B. disticha-treated ly lower SBP on PTD9 when compared to the group treated with diaze- groups which increased response with an increase in dosage when pam (mean difference of 4.63 ± 1.83 mm Hg, p b 0.02). At PTD30 low, medium and high dose treatment groups were compared to (long-term observations), only the group treated with a high dose of vehicle-treated MS animals (mean differences of 2.48 ± 4.08, 5.70 ± B. disticha had a significantly reduced mean SBP when compared to the 4.08 and 8.80 ± 4.08 mm Hg, respectively). Although this response vehicle treatment in MS mice (mean difference of 4.84 ± 1.78 mm Hg, was absent at PTD30, it was observed that the medium dose group sig- p b 0.02). In contrast, when compared to diazepam-treated MS mice, nificantly reduced DBP when compared to the low dose group of medium and high doses of B. disticha-treated MS mice had significantly B. disticha treatment (mean difference: 6.2 ± 2.69 mm Hg, p b 0.4, lower SBP on PTD30 with mean differences of 3.85 ± 1.78, p b 0.05 Fig. 2). Generally, DBP decreased in all groups over time, but, the change and 5.46 ± 1.78 mm Hg, p b 0.01, respectively. MS mice treated with in DBP during the recording periods was comparable among all test low dose of B. disticha had a significantly smaller change in SBP than groups (Fig. 2). the vehicle (p b 0.03), medium (p b 0.04) and high dose (p b 0.01) (Fig. 2). However, all the MS groups given vehicle, B. disticha extract or 3.1.3. Mean arterial pressure (MAP) diazepam treatments had comparable changes in SBP to control, non- MS mice treated with a low dose of B. disticha had a significantly separated group (Fig. 2). Lastly, dose-dependent effect of B. disticha reduced MAP when compared to the vehicle group (mean difference treatment in MS mice on SBP was evident on PTD30 i.e. increasing dose of 8.5 ± 3.4 mm Hg. p b 0.02) at PTD9. However, this response pattern from low through medium to high dose proportionally increased the was not evident at PTD30 (p N 0.05). On the other hand, MS mice treat- magnitude of SBP differences when compared to vehicle (0.86 ± 1.78, ed with a medium dose of B. disticha had a significantly higher MAP 3.23 ± 1.78 and 4.84 ± 1.78 mm Hg, respectively) or to diazepam when compared to those treated with diazepam at PTD30 (mean differ- (0.616 ± 1.78, 1.48 ± 1.78, 3.85 ± 1.78 and 5.46 ± 1.78 mm Hg, respec- ence of 5.5 ± 2.4 mm Hg, p b 0.04) but comparable to vehicle group (p tively) for vehicle, low, medium and high doses of B. disticha, respective- N 0.05). The change in MAP for the low dose B. disticha-treated group ly. This trend was confirmed when the magnitude changes in SBP was significantly smaller when compared to the vehicle or the medium between PTD9 and 30 were compared among the three doses of dose of B. disticha-treated animals (p b 0.05) (Fig. 2). There was no B. disticha (Fig. 2). dose-dependent effect of B. disticha on MAP. 36 W. Pote et al. / South African Journal of Botany 94 (2014) 33–39

Fig. 2. The diagram illustrates the cardiovascular response (change in blood pressure (BP)) to repeated exposure to acute mixing (AMS) and restraint stress in BALB/c mice. Changes in systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure (MAP) were given by subtracting recordings made on PTD9 from PTD30 recordings. Control (un-separated, and maternally separated (MS)) mice were gavaged with vehicle (Groups A and B respectively) while four other MS groups were given B. disticha aqueous ethanolic extract at low (LDBD, 10 mg/kg body weight (BW)), medium (MDBD, 25 mg/kg BW) and high doses (40 mg/kg BW) for Groups C, D and E, respectively and diazepam (DZP) at 1 mg/kg BW (Group F). *p b 0.05 (significant differences when treatment with B. disticha (Groups C, D and E) was compared to vehicle (Group B) in MS mice) and #p b 0.05 (significant dose response effect of B. disticha when low dose (Group C) is compared to either medium or high dose (Group D or E respectively).

3.1.4. Heart rate (HR) doses of B. disticha or diazepam had higher HRV when compared to The changes in HR were comparable among all the groups (p N 0.05) those given vehicle at PTD9 (mean differences of 1.85 ± 0.83, 1.83 ± (Fig. 2). However, it was noticed that MS mice treated with B. disticha 0.83 and 1.77 ± 0.83 bpm, respectively, p b 0.05). This effect disap- had a significantly lower HR when compared to the vehicle group at peared one month post-treatment. Furthermore, the magnitude of PTD30 (p b 0.05). change in HRV observed in MS mice treated with either a low or medi- um dose of B. disticha, or diazepam was significantly smaller than that in 3.2. Long-term autonomic reactivity in response to B. disticha treatment in MS mice given vehicle (p b 0.05) (Fig. 3). MS mice 4. Discussion 3.2.1. Blood pressure variability (BPV) Blood pressure variability (BPV) was estimated by measuring the The present results show that adult mice exposed to early maternal standard deviation of the MAP (SDMAP) of the six experimental groups separation (MS) and subjected to acute stressors displayed elevated (Igosheva et al., 2004). Comparisons across all groups at PTD9 showed blood pressure (BP) and decreased heart rate (HR) over the one that BPV was comparable. However, it was observed that, at PTD30, all month observation period. It is interesting that the changes in cardio- MS mice treatment groups, given vehicle; low, medium and high vascular response were restricted only to the initial testing period. Spe- doses of B. disticha; or diazepam, had a significantly higher BPV when cifically, MS mice exhibited increased SBP and decreased HR at PTD9 as compared to control (un-separated) mice treated with vehicle (mean was observed earlier after immediate withdrawal of treatments on differences of 3.44 ± 1.48, 3.27 ± 1.48, 4.00 ± 1.48, 3.14 ± 1.48 and PTD2 (Pote et al., 2013). However, this response to acute stress in MS 3.26 ± 1.48 mm Hg respectively, p b 0.05). BPV improved over time mice was absent on PTD30 suggesting that maternal separation is a across all groups. However, neither B. disticha group nor diazepam weak model of anxiety as reported previously (Faure et al., 2006; group displayed significant differences on BPV when compared to Liebsch et al., 1998). This may also be caused by habituation of MS vehicle in MS mice (p N 0.05). The changes in BPV were comparable mice to repeated exposure of the same stressor. Therefore, future across all treatment groups (p N 0.05) (Fig. 3). follow-up studies need to vary stressors in the MS model in order to continue simulating the underlying autonomic disturbances. This 3.2.2. Heart rate variability (HRV) study also showed that blood pressure variability (BPV) was increased HRV was estimated by calculating the mean standard deviation of in MS mice. BPV is positively related to end-organ damage (Cohen and

HR (SDHR) for all treatment groups. The HRV of MS mice was compara- Benjamin, 2006; Igosheva et al., 2004; Mancia and Parati, 2003)hence ble to that of the control un-separated group, during the entire study pe- maternal separation may cause increased cardiac damage in mice. riod, despite being challenged by repeated acute stressors at PTD9 and Repeated maternal separation may augment cardiovascular reactiv- PTD30. However, it was noticed that MS mice given low and medium ity and increase long-term anxiety-like and depression-related W. Pote et al. / South African Journal of Botany 94 (2014) 33–39 37

Fig. 3. A graph showing the autonomic reactivity to repeated exposure to acute mixing (AMS) and restraint stress in BALB/c mice. Changes in blood pressure variability (BPV) and heart rate variability (HRV) were given by subtracting recordings made on PTD9 from PTD30 recordings. Control (un-separated, and maternally separated (MS)) mice were gavaged with vehicle (Groups A and B respectively) while four other MS groups were given B. disticha aqueous ethanolic extract at low (LDBD, 10 mg/kg body weight (BW)), medium (MDBD, 25 mg/kg BW) and high doses (40 mg/kg BW) for Groups C, D and E, respectively and diazepam (DZP) at 1 mg/kg BW (Group F). * p b 0.05 (significant differences when treatment with B. disticha (Groups C, D and E) was compared to vehicle (Group B) in MS mice). behaviors in response to acute stressors in adults (Caldji et al., 2000; short-term antihypertensive activity at 10 mg/kg BW. Those gavaged Daniels et al., 2004; Faure et al., 2007; Huot et al., 2001; Kalinichev with medium dose had significantly decreased SBP and DBP on PTD30 et al., 2002; Lippmann et al., 2007; McIntosh et al., 1999; Pote et al., pointing to long-term effects of B. disticha at a dose of 25 mg/kg BW. 2013; Wigger and Neumann, 1999). Earlier studies demonstrated that However, the group treated with a high dose had a significantly reduced high anxiety breeds of rats are more sensitive to the anxiolytic effect SBP, DBP and MAP thus exhibiting short-term and long-term antihyper- of diazepam than low anxiety breeds (Liebsch et al., 1998). In the pres- tensive effects of B. disticha at 40 mg/kg BW. ent study, MS mice treated with diazepam had comparable BP and HR These results indicate that low doses of B. disticha are only effective to vehicle-treated MS group. The results suggest that diazepam is inef- for about one week and do not persist longer while the effects of higher fective in treatment of cardiovascular disturbances seen in maternally doses of B. disticha on SBP start one week and persist for more than a separated mice. month. The cardiovascular effects of B. disticha in maternally separated The increased BP in MS mice in response to AMS, observed in this mice on SBP were also found to be dose-dependent. These effects of study, may be mediated through exaggerated behavioral and neuroen- B. disticha extract can be attributed to several alkaloids present in the docrine stress responses, increased secretion of catecholamines to plant that mediate their biological activities through the cholinergic, ad- mobilize energy to meet raised metabolic requirements, increased sym- renergic and/or serotonergic systems (Bastida et al., 2011; Cheesman pathetic tone to optimize cardiovascular and respiratory functions, and et al., 2012; Nair et al., 2013; Nair and Van Staden, 2014; Neergaard a slightly delayed increase in glucocorticoid secretion to suppress the et al., 2009; Nielsen et al., 2004; Sandager et al., 2005; Viladomat et al., acute response (Daniels et al., 2004, 2009; Cohen and Benjamin, 2006; 1997). Faure et al., 2006; Øverli, 2001). These disturbances may be mediated B. disticha extract may directly or indirectly reduce physical patterns, by dysfunction of central neurotransmitter pathways (monoamine blood pressure or respiratory rate, heightened in animals subjected to receptors and production); intracellular transduction messenger sys- both maternal separation and acute mixing stress through the central tem malfunction (G proteins, cyclic adenosine monophosphate); hyper- monoamine neurotransmitters serotonin (5-hydroxytryptamin, 5-HT), activity of the hypothalamic–pituitary–adrenal (HPA)-axis or altered dopamine (DA) and norepinephrine (NE) (Cohen and Benjamin, 2006; neurotrophin levels (Daniels et al., 2004, 2009; Faure et al., 2006, Øverli, 2001). The phyto-constituents of the plant extract or their me- 2007; Head and Kelly, 2009; Øverli, 2001; Sarris and Kavanagh, 2009). tabolites may reach the central nervous system (Gadaga et al., 2011; Nyazema and Ndiweni, 1986) and effect their actions mainly by affect- 4.1. Long-term cardiovascular response to B. disticha treatment in adult MS ing these monoamine neurotransmitter systems in maternally separat- mice ed animals. Studies done by Nielsen et al. (2004) and Sandager et al. (2005) have shown that a crude extract of B. disticha has high affinity Maternally separated mice treated with B. disticha showed signifi- for the binding site on the serotonin transporter protein (SERT) cantly reduced cardiovascular parameters when compared to those in vitro. Furthermore, similar studies found that the plant alkaloids given vehicle or diazepam. MS mice treated with a low dose of have inhibitory activity on serotonin transporter protein (SERT) and

B. disticha had significantly low SBP, DBP and MAP on PTD9 suggesting some affinity for serotonin receptors (5-HT1A)(Neergaard et al., 2009; 38 W. Pote et al. / South African Journal of Botany 94 (2014) 33–39

Sandager et al., 2005). This is believed to be the main mechanism by Chuma, D., Tagwireyi, D., Gadaga, L.L., 2010. Investigation of the anxiolytic-like activity of Boophane disticha extract in mice. Bachelor of Pharmacy Thesis, University of which this plant exerts its anxiolytic and antidepressant activities Zimbabwe Library (Unpublished results). in vivo since blocking the serotonin receptors with cyproheptadine, Cohen, H., Benjamin, J., 2006. Power spectrum analysis and cardiovascular morbidity in decreased toxicity of B. disticha (Mutseura et al., 2013). The present anxiety disorders. Autonomic Neuroscience: Basic and Clinical 128, 1–8. fi fi Daniels, W.M., Pietersen, C.Y., Carstens, M.E., Stein, D.J., 2004. 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Early maternal separation treated with diazepam or B. disticha (low and medium doses) had alters the response to traumatization resulting in increased levels of hippocampal significantly elevated heart rate variability (HRV) on PTD9. This may neurotrophic factors. Metabolic Brain Disorders 22 (2), 183–195. be indicative of short-term anxiolytic activity of B. disticha since HRV Gadaga, L.L., 2012. Investigation of the toxicological and pharmacological activity of a is decreased in anxiety disorders and anxiolytic drugs partly correct hydroethanolic extract of Boophone disticha bulb. Masters of Philosophy Thesis, University of Zimbabwe Library (Unpublished results). this abnormality by acting on the autonomic nervous system (Cohen Gadaga, L.L., Tagwireyi, D., Dzangare, J., Nhachi, C.F.B., 2011. Acute oral toxicity and and Benjamin, 2006; Depino and Gross, 2007; Igosheva et al., 2004; neurobehavioral toxicological effects of a hydroethanolic extract of Boophone disticha – Volkmar et al., 2005). These results are consistent with previous results in rats. Human and Experimental Toxicology 30 (8), 972 980. Gelfand, M., Mitchell, C.S., 1952. Buphanine poisoning in man. South African Medical in our laboratory which found that B. disticha exhibited anxiolytic-like Journal 26, 573–574. activity in open field, souk, elevated plus maze and marble bearing Gelfand, M., Mavi, S., Drummond, R.B., Ndemera, B., 1985. The Traditional Medical Practi- tests (Chuma et al., 2010; Gadaga, 2012; Musarira et al., 2011; tioner in Zimbabwe. Mambo Press, Gweru p. 296. Gomes, N.G.M., Campos, M.G., Orfão, J.M.C., Ribeiro, C.a F., 2009. with neurobiolog- Punungwe et al., 2013; Tsigo et al., 2013). ical activity as potential targets for drug discovery. 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We are very grateful to the University of Zimbabwe Research Board Behavioural, physiological, and neuroendocrine stress responses and differential for financial assistance (Grant Number: RB/108/11) and the Depart- sensitivity to diazepam in two Wistar rat lines selectively bred for high- and low- – ments and staff in Faculties of Veterinary Science, Science and College anxiety-related behaviour. Neuropsychopharmacology 19, 381 396. Lippmann, M., Bress, A., Nemeroff, C.B., Plotsky, P.M., Monteggia, L.M., 2007. Long-term of Health Sciences, University of Zimbabwe for their unwavering sup- behavioural and molecular alterations associated with maternal separation in rats. port, facilities and equipment used in this project. Many thanks go to European Journal of Neuroscience 25, 3091–3098. Mr Zulu Daniel for helping us during plant collection, extraction and Mancia, G., Parati, G., 2003. The role of blood pressure variability in end-organ damage. 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