Role of Gabanergic and, or Serotonergic in the Anti-seizure Activity of Methanol Extract of Crinum jagus (J. Thomps) in Experimental Mice

Objective: Crinum jagus is used in traditional African medicine in the treatment of epilepsy, pain and inflammations. Methods: Anticonvulsant activity was investigated using picrotoxin (PCT) and strychnine (STR) tests in experimental paradigm. Results: Crinum jagus leaf methanol extract (200, 400, and 800?mg?kg?1) potentiated hexobarbitone-induced sleeping time and significantly (p<0.05) shortened the duration of convulsions in PCT-induced seizures. Delay in the onset of convulsions in PCT-induced seizure were very significant (p<0.05). Reduction in the frequency of seizures was also significant (p<0.05) in the test. Diazepam (5?mg?kg?1) was used as reference anticonvulsant drugs in the experimental models. While, CJB failed to protect the animals against picrotocin-induced convulsion. Neither the extract of CJL nor CJB confer significant effect on STR-induced convulsion. Flumazenil (GABA receptor antagonist) and cyproheptadine (5-HT2 receptor antagonist) blocked the effect of CJL extract in the PCT tests significantly suggesting that Crinum jagus may be acting by enhancing the effects of the GABAergic and serotonergic systems. Conclusion: The data obtained suggest that methanol leaf extract of C. jagus possessed significant anticonvulsant effect, thereby confirming the traditional uses of C. jagus in the treatment of epilepsies; mechanisms of which may involve interaction with GABAergic and serotonergic pathway.

Actions of progesterone on depression-like behavior in a model of surgical menopause are mediated by GABAA receptors / Las acciones de progesterona sobre la conducta tipo depresión en un modelo de menopausia quirúrgica son mediadas por receptores GABAA

Abstract Introduction In rats, long-term ovariectomy results in low concentrations of steroid hormones and reproduces anxiety- and depression-like behavior after surgical menopause in women. Progesterone produces antidepressant-like effects two weeks post-ovariectomy (i.e., early post-ovariectomy) through actions on γ-aminobutyric acid-A (GABAA) receptors, but its antidepressant-like effects and mechanism of action in rats eight weeks post-ovariectomy (i.e., late post-ovariectomy, considered a model of surgical menopause) remain unknown. Objective To explore the antidepressant-like effects of progesterone and the participation of GABAA receptors in rats eight weeks post-ovariectomy. Method Long-term ovariectomized female Wistar rats were treated sub-acutely with vehicle or progesterone (.5, 1, and 2 mg/kg) and subjected to the open field and forced swim tests, and behavior was compared with cycling or fluoxetine-treated rats. The rats were then pretreated with picrotoxin (1 mg/kg) followed by progesterone (1 mg/kg) to explore the role of GABAA receptors in long-term-induced depression-like behavior. Results Long-term ovariectomized rats exhibited depression-like behavior in the forced swim test compared with intact rats, an effect that was not observed in progesterone- and fluoxetine-treated long-term ovariectomized rats. These effects were not attributable to psychomotor alterations. In the open field test, the time spent rearing and grooming was lower in ovariectomized rats compared with intact rats, which was not observed in progesterone- and fluoxetine-treated rats. Picrotoxin blocked the effects of progesterone in both behavioral tests. Discussion and conclusion These results indicated that sub-acute progesterone treatment reduced depression-like behavior through actions on GABAA receptors in a rat model of surgical menopause.

Resumen Introducción En la rata, la ovariectomía a largo plazo reproduce algunos síntomas de la menopausia quirúrgica, incluyendo la conducta de tipo depresiva. La progesterona produce efectos tipo antidepresivo en ratas con dos semanas de post-ovariectomía (post-ovariectomía temprana) con participación del receptor GABAA, pero se desconoce si este efecto y mecanismo de acción se mantiene en ratas con ocho semanas de post-ovariectomía (post-ovariectomía tardía considerada como un modelo de menopausia quirúrgica). Objetivo Evaluar el efecto tipo antidepresivo de la progesterona y la participación del receptor GABAA en ratas con ocho semanas de post-ovariectomía. Método Ratas con ocho semanas de post-ovariectomía fueron tratadas sub-agudamente con vehículo o progesterona (.5, 1, y 2 mg/kg) y comparadas con ratas intactas u ovariectomizadas tratadas con fluoxetina, evaluadas en campo abierto y nado forzado. Posteriormente, se identificó la participación del receptor GABAA en los efectos de progesterona (1 mg/kg) mediante el pretratamiento con picrotoxina (1 mg/kg). Resultados En nado forzado, la ovariectomía produjo conductas tipo depresión en comparación con las ratas intactas de la gónada, un efecto prevenido por la administración de progesterona y fluoxetina. En campo abierto, no hubo cambios significativos en la locomoción, pero la conducta vertical y el acicalamiento fueron bajos en las ratas ovariectomizadas respecto a las ratas intactas; lo cual fue prevenido por progesterona y fluoxetina. La picrotoxina bloqueó los efectos de la progesterona en ambas pruebas conductuales. Discusión y conclusión El tratamiento subagudo con progesterona reduce la conducta tipo depresión inducida en un modelo de menopausia quirúrgica con participación del receptor GABAA.

Terminalia arjuna bark extract attenuates picrotoxin-induced behavioral changes by activation of serotonergic, dopaminergic, GABAergic and antioxidant systems / 中国天然药物

Stress and emotion are associated with several illnesses from headaches to heart diseases and immune deficiencies to central nervous system. Terminalia arjuna has been referred as traditional Indian medicine for several ailments. The present study aimed to elucidate the effect of T. arjuna bark extract (TA) against picrotoxin-induced anxiety. Forty two male Balb/c mice were randomly divided into six experimental groups (n = 7): control, diazepam (1.5 mg·kg), picrotoxin (1 mg·kg) and three TA treatemt groups (25, 50, and 100 mg/kg). Behavioral paradigms and PCR studies were performed to determine the effect of TA against picrotoxin-induced anxiety. The results showed that TA supplementation increased locomotion towards open arm (EPM) and illuminated area (light-dark box test), and increased rearing frequency (open field test) in a dose dependent manner, compared to picrotoxin (P < 0.05). Furthermore, TA increased number of licks and shocks in Vogel's conflict. PCR studies showed an up-regulation of several genes, such as BDNF, IP, DL, CREB, GABA, SOD, GPx, and GR in TA administered groups. In conclusion, alcoholic extract of TA bark showed protective activity against picrotoxin in mice by modulation of genes related to synaptic plasticity, neurotransmitters, and antioxidant enzymes.

Evaluation of the anticonvulsant activity of the essential oil of Myrothamnus moschatus in convulsion induced by pentylenetetrazole and picrotoxin

Objective: To evaluate the anticonvulsant effect of the essential oil of Myrothamnus moschatus (M. moschatus) in convulsion induced by pentylenetetrazole and picrotoxin in rodent models. Methods: The essential oil of the aerial parts of M. moschatus was extracted by steam distillation. Thereafter, it was injected subcutaneously to rats and mice at escalating doses (0.1–0.8 mL/kg). Ten minutes after drug injection, pentylenetetrazole was injected intraperitoneally to rats and picrotoxin was administered to mice by the same route. Diazepam served as the positive control. Every single animal was placed into transparent cage and observed for convulsive behavior for 30 min by using ordinary security cameras connected to a video recorder. Death occurring for a period of 24 h was also recorded. Results: The essential oil at 0.8 mL/kg completely arrested the pentylenetetrazole-induced convulsion without any sedative effect and delayed its appearance at lower doses, but showed moderate activities on picrotoxin-induced convulsion. For the rats treated with pen-tylenetetrazole alone, the mortality was 100%within 1 h, but for the rats pre-treated with the essential oil, the mortality was 0%. For the mice treated with picrotoxin, the mortality rate was also 100%, while 20%–100%died in those that had been pre-treated with the oil. Conclusions: The results confirmed at least partly the traditional uses of the smoke of M. moschatus for the management of convulsion, and implied that the essential oil may inhibit the convulsion by GABAergic neuromodulation.

Evaluation of the anticonvulsant activity of the essential oil of Myrothamnus moschatus in convulsion induced by pentylenetetrazole and picrotoxin

Objective: To evaluate the anticonvulsant effect of the essential oil of Myrothamnus moschatus (M. moschatus) in convulsion induced by pentylenetetrazole and picrotoxin in rodent models. Methods: The essential oil of the aerial parts of M. moschatus was extracted by steam distillation. Thereafter, it was injected subcutaneously to rats and mice at escalating doses (0.1-0.8 mL/kg). Ten minutes after drug injection, pentylenetetrazole was injected intraperitoneally to rats and picrotoxin was administered to mice by the same route. Diazepam served as the positive control. Every single animal was placed into transparent cage and observed for convulsive behavior for 30 min by using ordinary security cameras connected to a video recorder. Death occurring for a period of 24 h was also recorded. Results: The essential oil at 0.8 mL/kg completely arrested the pentylenetetrazole-induced convulsion without any sedative effect and delayed its appearance at lower doses, but showed moderate activities on picrotoxin-induced convulsion. For the rats treated with pentylenetetrazole alone, the mortality was 100% within 1 h, but for the rats pre-treated with the essential oil, the mortality was 0%. For the mice treated with picrotoxin, the mortality rate was also 100%, while 20%-100% died in those that had been pre-treated with the oil. Conclusions: The results confirmed at least partly the traditional uses of the smoke of M. moschatus for the management of convulsion, and implied that the essential oil may inhibit the convulsion by GABAergic neuromodulation.

Antiepileptogenic and Anticonvulsant Actions of Dalbergia saxatilis (Hook, F.) in Sub-toxic Chemical Kindling and Toxic Convulsant Models.

Aims: The aqueous root extract of Dalbergia saxatilis (DS) is used in traditional African medicine to manage convulsions and epilepsies. This study aimed at investigating DS action against models that mimic seizure development in the neurons of epileptics, the sub-toxic dose kindling models. Study Design: Sub-toxic doses of strychnine and picrotoxin chemical kindling models; as well as single-dose toxic bicuculline convulsive models in mice. Place and Duration of Study: Neuropharmacology Unit Laboratory, Department of Pharmacology, College of Medicine, University of Lagos, Lagos, Nigeria, between July 2006 and March 2008. Methodology: Strychnine kindling was produced by a 48h interval, i.m administration of 1.5mg/kg strychnine for 9 trials. The mice were treated with 200mg/kg, p.o. DS, before strychnine thus: Group I: throughout the 1st - 9th kindling; group II: During the 1st - 5th kindling; and group III: during the 6th - 9th kindling trials. Control group received distilled water instead of DS throughout the 1st - 9th kindling trials. For picrotoxin study, a subconvulsant dose of 1.5mg/kg picrotoxin was injected i.p. 3 times a week for 10 weeks, 200mg/kg of DS was administered orally before picrotoxin thus: Group I: throughout the 1st - 30th kindling trials; group II: during the 1st - 12th kindling trials; group III: during the 13th - 30th kindling trials; control group received distilled water instead of DS throughout the 30 trials. Behavioural seizures were classified for seizure stages. In another study, DS (50- 200 mg/kg, p.o.) was administered to mice, 30 min. before 10mg/kg, s.c. bicuculline and onset to seizures and time to death noted. Results: DS significantly (P=.05) retarded the development and progression of strychnine kindling, but did not reverse already reached kindled state. Moreover, DS significantly (P=.05) retarded the development of picrotoxin kindling, decreased the scoring from kindling progression and prevented convulsion in fully picrotoxin-kindled mice. A significant delay of seizure onset, with complete protection at 200mg/kg DS was produced against bicuculline seizures in mice. Conclusion: DS may attenuate development of seizures in both GABAergic and glycinergic mechanisms and be useful in the prevention of seizures as well as neuroprotection in epileptics, justifying its use in the folkloric management of epilepsies.

Anticonvulsant activity of alcoholic root extract of Cardiospermum halicacabum

The aim of the present study was to evaluate the anticonvulsant effects of alcoholic root extract of Cardiospermum halicacabum L., Sapindaceae (ARECH), on the various murine models of epilepsy. The root extract of the plant was administered p.o. to male swiss albino mice at doses of 30, 100 and 300 mg/kg before evaluation. The brain monoamine levels were determined after two days administration. ARECH at doses of 100 and 300 mg/kg significantly delayed the onset of clonus and tonus in pentylenetetrazol, isoniazid and picrotoxin-induced convulsions. Tonic hind limb extension was also decreased at doses of 100 and 300 mg/kg as compared to vehicle control in maximal electroshock model. No significant motor toxicity was observed even at a highest dose administered, i.e. 900 mg/kg. Brain monoamine analysis by HPLC revealed a significant increase in GABAergic activity in C+ (in cerebellum) and C- (except cerebellum). These results suggested that ARECH possesses a significant anticonvulsant activity with a low motor toxicity profile. This activity may be attributed to an increase in GABAergic activity.

Reduced hippocampal GABAergic function in Wistar audiogenic rats

Epilepsy is a neurological disorder associated with excitatory and inhibitory imbalance within the underlying neural network. This study evaluated inhibitory γ-amino-butyric acid (GABA)ergic modulation in the CA1 region of the hippocampus of male Wistar rats and Wistar audiogenic rats (aged 90 ± 3 days), a strain of inbred animals susceptible to audiogenic seizures. Field excitatory postsynaptic potentials and population spike complexes in response to Schaffer collateral fiber stimulation were recorded in hippocampal slices before and during application of picrotoxin (50 µM, 60 min), a GABA A antagonist, and the size of the population spike was quantified by measuring its amplitude and slope. In control audiogenic-resistant Wistar rats (N = 9), picrotoxin significantly increased both the amplitude of the population spike by 51 ± 19 percent and its maximum slope by 73 ± 21 percent. In contrast, in slices from Wistar audiogenic rats (N = 6), picrotoxin caused no statistically significant change in population spike amplitude (33 ± 46 percent) or slope (11 ± 29 percent). Data are reported as means ± SEM. This result indicates a functional reduction of GABAergic neurotransmission in hippocampal slices from Wistar audiogenic rats.

Anticonvulsant evaluation of Rauvolfia ligustrina Willd. ex Roem. & Schult., Apocynaceae, in rodents / Avaliação anticonvulsivante de Rauvolfia ligustrina Willd. ex Roem. & Schult., Apocynaceae, em roedores

The Aim of this study was to evaluated the effects of the ethanol extract of Rauvolfia ligustrina Willd. ex Roem. & Schult., Apocynaceae, roots (EER) in animal models of epilepsy. The EER increased the latency for convulsions significantly different from control (p<0,05) and in the PTZ induced convulsions test on 62,5 mg/kg (i.p.) decreased mortality. This effect was blocked by flumazenil administration, suggesting an involvement of GABAergic system in the anticonvulsant activity of EER. The EER had a moderate effect only against PIC- or STR-induced convulsions at doses 125 and 250 mg/kg. But in the MES test it did not demonstrate effect on this animal model. Therefore, the EER reduced the development of PTZ-induced kindling in both experimental groups. It also significantly (p<0.05) decreased the latency for convulsions and reduced its percentage. Our results suggest that EER owns anticonvulsant property.

O presente estudo buscou avaliar os efeitos do extrato etanólico das raízes de Rauvolfia ligustrina Willd. ex Roem. & Schult., Apocynaceae, (EER) e sua possível atividade anticonvulsivante em roedores. No teste das convulsões induzidas pelo pentilenotetrazol (PTZ) os animais tratados com EER, 250 mg/kg (i.p.), apresentaram aumento significativo (p<0,05) da latência para o aparecimento das convulsões (328,9±47,5) quando comparado aos do grupo controle (103,5±21,8) e reduziu o número de óbitos. Esse efeito foi bloqueado pela administração do flumazenil. O EER produziu aumento significativo (p<0,05) na latência nos testes da picrotoxina (PIC) e da estricnina (EST), nas maiores doses. No modelo do eletrochoque auricular o EER não produziu alterações significativas em nenhum dos parâmetros avaliados. Entretanto, no modelo do abrasamento induzido pelo PTZ, a administração com o EER produziu um efeito protetor, atenuando de forma significativa (p<0,05) o desenvolvimento e a severidade das crises convulsivas. Os resultados, sugerem que o EER induziu efeito anticonvulsivante em roedores e que o sistema GABAérgico pode estar envolvido nessa resposta.

EFFECTS OF UROTENSIN II ON ELECTRICAL ACTIVITY OF PARAVENTRICULAR NEURONS IN RAT HYPOTHALAMIC SLICES / 神经解剖学杂志

Effects of urotensin II (UII) on paraventricular nucleus (PVN) neurons of hypothalamus from brain slices of rats were examined by using extracellular recording technique. The results are as follows: (1) In response to application of UII (0.3, 3.0, 30.0, 300.0 nmol/L, n=39) into the perfusate for 2 min, the spontaneous discharge rates (SDR) of 32/39 (82.05% ) neurons were significantly decreased in a dose-dependent manner; (2) Pretreatment with bicuculline (BIC, 100 μmol/L), a specific GABAA receptor antagonist, led to a marked increase in SDR of 5/7 ( 71.43% ) neurons in an epileptiform pattern. The increased discharges were not significantly changed after UII ( 30.0 nmol/L ) was applied into the perfusate for 2 min; (3) Pretreatment with picrotoxin ( PIC, 50 μmol/L ), a selective blocker of Cl- channel, led to an increase in the SDR of all 12/12 (100%) neurons. The increased discharges were not influenced by the applied UII (30.0 nmol/L) for 2 min in 11/12 (91.67%) neurons; (4) Application of nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 50 μmol/L ) into the perfusate could significantly augment the SDR of 11/12 ( 91.67% ) neurons , while UII ( 30.0 nmol/L ) applied into the perfusate for 2 min led the augmented SDR of all (12/12, 100%) neurons decrease. The results suggest that UII decreases the excitability of PVN neurons of hypothalamus by potentiating GABAA receptor-mediated Cl- current.

Protective effects of allopregnanolone against different seizure models in mice / 中国临床药理学与治疗学

Aim To examine the protective effects of allopregnanolone against seizure on different animal models.Methods　The protective effects of allopregnanolone against maximal electrical seizure (MES) and picrotoxin-induced seizure were studied in C57 mice 15 minutes after vehicle or drug intraperitoneal administration.Results　In the MES test, we found that pretreatment with the phenobarbital or allopregnanolone produced a dose-dependent protective effect against seizure. The potency (ED50 value) of phenobarbital in the MES test was 2.40 mg·kg-1, with 95% confidence interval range from 1.22 to 4.72 mg·kg-1. The potency (ED50 value) of allopregnanolone in the MES test was 0.086 mg·kg-1, with 95%confidence interval range from 0.037 to 0.201 mg·kg-1, which was significantly higher than that of phenobarbital (P<0.01). The combination study of half ED50 values of phenobarbital and allopregnanolone resulted in a 80% of protective effect in MES test, which was higher than 50% produced by either phenobarbital or allopregnanolone at their ED50 values respectively. This result indicated that there was a synergism between phenobarbital and allopregnanolone in their anticonvulsant activities. In the picrotoxin test, we found that pretreatment with the allopregnanolone also produced a dose-dependent protective effect against picrotoxin-induced seizure. The potency of allopregnanolone in the picrotoxin seizure test was 0.123 mg·kg-1, with 95% confidence interval range from 0.058 to 0.263 mg·kg-1.Conclusion　Allopregnanolone(ip) could protect different seizures in a dose-dependent manner,had a higher potency than phenobarbital,and had synergism with phenobarbital in the MES test.

Protective effects of allopregnanoloneagainst different seizure models in mice / 中国临床药理学与治疗学

Aim To examine the protective effects of allopregnanolone against seizure on different animal models.Methods The protective effects of allopregnanolone against maximal electrical seizure (MES) and picrotoxin-induced seizure were studied in C57 mice 15 minutes after vehicle or drug intraperitoneal administration.Results In the MES test, we found that pretreatment with the phenobarbital or allopregnanolone produced a dose-dependent protective effect against seizure. The potency (ED50 value) of phenobarbital in the MES test was 2.40 mg?kg-1, with 95% confidence interval range from 1.22 to 4.72 mg?kg-1. The potency (ED50 value) of allopregnanolone in the MES test was 0.086 mg?kg-1, with 95% confidence interval range from 0.037 to 0.201 mg?kg-1, which was significantly higher than that of phenobarbital (P

Changes in γ-aminobutyric acid during different stages of picrotoxininduced seizure, and the effect of pretreatment with γ-acetylenic GABA and phenobarbital.

Changes in GABA content of various brain areas during different stages of picrotoxin-induced seizures and following pretreatment with the anti-convulsants phenobarbital and γ-acetylenic GABA were studied. Picrotoxin (6mg/kg) produced clonic/tonic convulsions associated with a 34% reduction in GABA content of the sensory motor cortex. A reduction of 24% was observed 1 min before the onset of seizure and the reduction in GABA content was reversible 20 min after the convulsion. No significant changes were observed in the cerebellum or spinal cord/medulla oblongata. Pretreatment with phenobarbital (100mg/kg) delayed the onset of convulsion and decreased the mortality rate without causing any change in GABA content at the preconvulsive, convulsive or post-convulsive stages. γ-Acetylenic GABA (100mg/kg) has elevated GABA levels in different areas of the brain by 2-3-fold after 60 min treatment. This increase was reduced by 44% during the onset of picrotoxin-induced seizures. Picrotoxin convulsion can occur in the presence of normal, reduced or even elevated brain GABA content. The only consistent factor is a one-third reduction in GABA content before the onset of seizure.

Long-term potentiation and the effects of 3 convulsants on its induction in hippocampal slices of rats / 第三军医大学学报

Long-term potentiation (LTP) of synaptic transmission between the dendrites of the pyramidal cells of CA[ region and the Schaffer-commissu-ral pathway was induced with electric stimulation in the isolated hippocampal slices of rats.The effects of 3 convulsants,soman,kianic acid.and picroto-xin,on the induction of LTP in this region were observed.It was found that a short series of electric impulses could effectively induce LTP in most of the slices of the hippocampus and the amplitude of the population spikes showed a similar change as the field excitatory postsynaptic potential did in the rising phase.Picrotoxin could facilitate the induction of LTP when it evoked an epileptoform electric activity in the slices,kianic acid could also evoke an epileptoform activity but significantly blocked the induction of LTP,and soman could not evoke obvious epileptoform activity but blocked the induction of LTP.The above findings suggest that a short series of electric impulses can effectively induce LTP between the pyramidal cells and the Schaffer-commisural pathway in the CA1 region,the effects of epileptoform activity on the induction of LTP depends on the mechanism to evoke the epileptoform activity,and the effects of soman on the induction of field potential may involve the noncholi-nergic system in the synaptic connections.

Effects of Picrotoxin on the Rate, Contractility and Action Potential of Isolated Frog Heart / 第三军医大学学报

Picrotoxin is an anatagninst of gamma-aminobutyric acid, which is an internal inhibition-transmitter in the central nervous system, Picrotoxin exerts a biphasic action on the blood pressure and heart rate in rats and cats in vivo. That is to say, in the initial stage, picrotoxin can lower the blood pressure and heart rate, and then an elevation of these two even above the original level can be observed, up to the present, from the authors limited literature, there has been no report dealing with the problem whether picrotoxin can act on an isolated heart directly.In this study, the heart of a frog was isolated and routine intubation of the heart was done for its perfusion. Physiological polyconduction instrument was inserted through a mechanical transducer to record the heart rale and myocardial contractility. A suspending glass microelectrode coupling with a microamplifier is used to record the action potential of the ventricular myocardium. Real time analysis of all the data was accomplished with a microcomputer. The dosages of picrotoxin used were 1,5, 3.0, 6.0, and 12.0 mg per kilogram of body weight.It was found that picrotcxin can directly act on the isolated frog heart. The results were as follows.1 ) Picrotoxin exerts inhibition on the special conduction system of the heart,and the A-V node and venous sinus are very sensitive. Complete or partial transmission block can be induced.2 ) It can elicit clearly a fall of the heart rate but no biphasic action can berevealed. 3) It can reduce the myocardial contractility, suggesting that the calciuminflow during the functioning period of the action potential is effected. 4 ) It can reduce the amplitude of the action potential but no effect on themaximal depolarization speed is observed, suggesting that picrotoxin islikely to affect the level of resting potential but not the action potentialin the depolarized period.

Effects of Picrotoxin Injection into Lateral Ventricle of the Cat on Cardiac Contractility and Renal Nerve Discharge / 第二军医大学学报

The present study was undertaken to observe the effect of picrotoxin(PT) injection into lateral ventricle (LV) on cardiac contractility (CC) and renal nerve discharge (RND).lt was found that PT injection into LV caused CC and RND to increase significantly, and this effect was dose-dependent.The effect of baroreflex on cardiovascular response produced by PT injection was also observed. Data suggested that PT injection into LV still caused CC and RND to increase when the buffer nerve was sectioned. The magnitude of increase was significantly larger than that of the intact buffer nerve. The results indicate that in the CNS, the block of gamma-aminobutyric acid (GABA) transmitter system not only could cause blood pressure and heart rate to increase, but also strengthen CC and RND; baroreflex could partly suppress cardiovascular response caused by PT injection.

THE EFFECT OF SINOMENINE ON EXPERIMENTAL ARRHYTHMIA / 西安交通大学学报(医学版)

The effects of Sinomenine on experimental arrhythmia were studied. The result showed that Sinomenine could shorten the arrhythmetic period induced by picrotoxin in rabbit and protect rat against arrhythmia induced by BaCl_2. Sinomenine was found to recover the arrhythmia induced by BaCl_2-Ach into sinus rhythm in mice, Beside these Sinomenine also showed significant antagonising to ischemic arrhythmia.