四氢孕酮对小鼠不同惊厥模型的保护作用
作者：于榕 姚明辉
单位：于榕 姚明辉(上海医科大学基础医学院药理教研室，上海 200032)
关键词：四氢孕酮；苯巴比妥；惊厥；最大电休克实验；印防己；ED50
中国临床药理学与治疗学000201
目的 观察四氢孕酮对不同动物惊厥模型的保护作用。方法 C57小鼠腹腔注射四氢孕酮15 min 后观察其对最大电休克实验(maximal electrical seizure, MES)或印防己所致惊厥的保护作用。结果 在MES试验， 四氢孕酮或苯巴比妥产生剂量依赖性的保护作用。苯巴比妥的ED50为2.40 mg.kg-1, 95%可信限为1.22至4.72 mg.kg-1。四氢孕酮的ED50为0.086 mg.kg-1, 95%可信限为0.037至0.201 mg.kg-1，显著较苯巴比妥强(P<0.01)。 四氢孕酮对印防己所致惊厥保护作用 的ED50为0.12 mg.kg-1。两药各1/2 ED50量的联合用药在MES试验产生80%的保护作用，高于50%。提示四氢孕酮和苯巴比妥具协同抗惊厥作用。在印防己致惊厥试验， 四氢孕酮亦产生剂量依赖性保护作用， ED50为0.123 mg.kg-1，95%可信限为0.085至0.263 mg.kg-1。结论腹腔注射四氢孕酮对MES或印防己所致惊厥具有剂量依赖性的保护作用；对MES， 四氢孕酮的保护作用显著大于苯巴比妥，并与后者有协同作用。
, http://www.100md.com
中图分类号 R965
Protective effects of allopregnanolone
against different seizure models in mice
YU Rong
(Department of Pharmacology, Shanghai Medical University,Shanghai 200032)
YAO Ming-Hui
(Department of Pharmacology, Shanghai Medical University,Shanghai 200032)
, http://www.100md.com
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.
, http://www.100md.com
Key words allopregnanolone; phenobarbital; seizure; maximal electrical seizure; picrotoxin; ED50
Neurosteroids are endogenous metabolites of certain steroid hormones that rapidly alter the excitability of neurons by direct actions on ligand-gated ion channels[1].Specifically,the endogenous 3α-hydroxyl ring A-reduced metabolites of progesterone,allopregnanolone produced a powerful enhancement of GABAA receptor- mediated responses in vitro by interaction with unique non-genomic recognition site on the GABAA receptor complex that is distinct from the benzodi-azepine, barbiturate, and GABA recognition sites[2,3].
, http://www.100md.com
Allopregnanolone has been proposed as putative anticonvulsant compound due to its ability to enhance GABAA-mediated neurotransmission[4].The γ-aminobutyric acid (GABAA) receptor Cl- channel complex is a major target for the action of therapeutically useful drugs such as benzodiazepines (BZD) and barbiturates that elicit at least some of their anticonvulsant effects via the GABAA receptor in the central nervous system. Considering the fact that the neurosteroids have their distinctive recognition site on the GABAA receptor complex,we therefore hypothesized that neurosteroids have anticonvulsant activity and their anticonvulsant profile might be different from that of benzodiazepines or barbiturates.Consequently, in the present study, we examined the protective effect of allopregnanolone against seizure on different animal models and compare to that of phenobarbital.
, 百拇医药
1 Material and method
1.1 Animals Male C57 mice (18～22 g) were obtained from animal department of Shanghai Medical University.Approved number 02～229. Animals were allowed to acclimatize with free access to food and water for a 48 h period before testing.
1.2 Drugs Allopregnanolone was purchased from Sigma Chemical Co.(St Louis,MO.USA). Stock solution of allopregnanolone was prepared in dimethyl sulfoxide (SP Jinshan Chemical Plant,Lot 790917) and further dilution was made using 0.9% saline. Phenobarbital was obtained from Shanghai Xinya Pharmaceutical Factory, Lot 860425-C2.All drug solutions were administered ip in a volume equaling 1% of the animal's body weight.
, http://www.100md.com
1.3 MES-induced seizure test Evaluations were carried out in a quiet,temperature controlled room(23 °C).Animals were fasted over- night and brought in the room 4 hours prior to experiment. Mice were injected intraperitoneally (ip) with different doses of phenobarbital and allopregnanolone 15 minutes before the MES test. Multifunctional Physiology Stimulator (Jialong Medical Instrument Co, Ltd.) was applied for stimulation (wave duration: 0.3 ms). Stimulating electrodes were placed on the mice cornea. Normal saline was used wet the electrode to guarantee the contact. Animals were observed right after the stimulation. Tonic extension was positive response. Stimulating parameter of voltage was adjusted to make all the mice to have positive responses before any treatment.
, http://www.100md.com
1.4 Picrotoxin-induced seizure test Mice were injected intraperitoneally (ip) with different doses of allopregnanolone or vehicle and 15 minutes later received a ip injection of the picrotoxin at dose of 5.5 mg.kg-1 . In the preliminary study, we found that this dose of picrotoxin could induce tonic seizure in 100 % of the mice within 15 minutes after the picrotoxin administration. Animals were observed for 15 minutes to record the number of mice showing tonic extension right after the picrotoxin administration.
, 百拇医药
1.5 Data analysis To construct dose-effect curves, allopregnanolone or phenobarbital was tested at several doses spanning the dose producing 50 % protection. At least 10 mice were tested at each dose. ED50 values and their 95% confidence intervals were determined by log-probit analysis using Bliss method. Comparison the ED50 values was analyzed using u test. In picrotoxin test, mice failing to show seizures 15 minutes after picrotoxin administration were scored as protected. Combination study was analyzed using Bürgi method [5].
, 百拇医药
2 Results
2.1 Protective activity of allopregnanolone in maximal electroshock seizure (MES) test Allopregnanolone was compared to phenobarbital for their protective activities in the maximal electroshock seizure test.Pretreatment with the phenobarbital 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. Pretreatment with the allopregnanolone also produced a dose-dependent protective effect against seizure. 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).Also the combination of phenobarbital and allopregnanolone was examined on its protective activity against seizure. Half ED50 values of phenobarbital and allopregnanolone were combined. This combination showed a 80% of protection, which was higher than 50% produced by either phenobarbital or allopregnanolone at their ED50 values respectively.
, 百拇医药
Tab 1 Comparison of the protective effects of allopregnanolone and phenobarbital on the maximal electroshock seizure in C57 mice Group
ED50/mg.kg-195%
confidence interval
Allopregnanolone
0.086**
0.037~0.201
Phenobarbital
, http://www.100md.com
2.40
1.22~4.72
Allopregnanolone group mice were administered with 0.01, 0.05, 0.1,0.5 and 1.0 mg.kg-1 of allopregnanolone, ip.Phenobarbital group mice were administered with 0.5, 1.0, 5.0,10 and 50 mg.kg-1 of phenobarbital injection, ip.At least 10 mice were tested at each dose. ED50 values and their 95% confidence intervals were determined by log-probit analysis using Bliss method. Comparison between the ED50 values was analyzed with u test. ** P<0.01
, http://www.100md.com
Fig 1 Dose-response relationship of allopregnanolone for the protection against picrotoxin-induced seizure
C57 mice were administered with 0.01, 0.05, 0.1, 0.5 and 1.0 mg.kg-1 of allopregnanolone, ip. 10 mice were tested at each dose. ED50 values and their 95% confidence intervals were determined by log-probit analysis using Bliss method. Mice failing to show seizures 15 minutes after picrotoxin administration were scored as protected.
, 百拇医药
2.1 Protective activity of allopregnanolone in picrotoxin seizure test Allopregnanolone was examined for protective activity in the picrotoxin seizure test. As illustrated in Fig 1,pretreatment with the allopregnanolone produced a dose- dependent protective effect against picrotoxin -induced seizure.The potency (ED50 value) 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.
, 百拇医药
Therefore, allopregnanolone administration had a protective activity against different seizures in MES and picrotoxin tests with a dose- dependent manner.Also,allopregnanolone had a higher potency than phenobarbital,and there was a synergistic action between allopregnanolone and phenobarbital.
3 Discussion
Several lines of recent investigation have shown that neurosteroid allopregnanolone allosterically modulate GABAergic transmission through a unique binding site on the GABA A receptor Cl- channel complex. This binding site has been found to be distinctly different from that of the benzodiazepines or the barbiturates site, respectively. In particular, the 3α-hydroxyl ring A-reduced metabolite of progesterone, allopregnanolone produced a potent enhancement of GABA A receptor responses in vitro. Since benzodiazepines or barbiturates were believed to produce anticonvulsant activity via the binding to the GABA A receptor complex, it was reasonable to speculate that allopregnanolone has a similar anticonvulsant activity like benzodiazepines or barbiturates. However, neurosteroids had their distinctive recognition site on the GABA A receptor complex, we therefore compared the protective effects of allopregnanolone and phenobarbital against seizures in MES and picrotoxin tests.
, http://www.100md.com
We found that either phenobarbital or allopregnanolone produced a dose-dependent protective effect against seizure in MES test. The ED50 value allopregnanolone was significantly smaller than that of phenobarbital. In other words, allopregnanolone had a higher potency than phenobarbital in preventing seizure. The combination study showed that there was a synergism between phenobarbital and allopregnanolone in their anticonvulsant activities. These results were consistent with the results from our previous ligand binding study on the primary cortical neuron, in which neurosteroid showed a higher potency than barbiturate [6]. It also suggested that the neurosteroid had a potential to be used alone or combined with other drugs, such as benzodiazepines or barbiturates, to treat epilepsy clinically. By doing so, the side effects of currently used drugs for epilepsy could be avoided since neurosteroids were endogenous in nature. In the picrotoxin test, we found pretreatment with the allopregnanolone also produced a dose-dependent protective effect against picrotoxin-induced seizure. This result support the finding of the MES test.
, 百拇医药
In conclusion, these results have demonstrated that allopregnanolone was more potent than phenobarbital in protecting against different seizures.
Yu Rong, male, 35 years old, Ph.D, associate professor, neuropharmacology
References
1，Paul SM, Purdy RH. Neuroactive steroids . FASEB J,1992; 6:2311
2，Majewska MD. Neurosteroids: endogenous bimodal modulators of GABAA receptor. Mechanism of action and physiological significance.Prog Neurobiol, 1992;38:379
, 百拇医药
3，Ticku MK.Drug modulation of GABAergic transmission. Sem Neurosci, 1991;3:211
4，Frye CA, Reed TA. Androgenic neurosteroids: antseizure effects in an animal model of epilepsy. Psy-choneuroendocrinology, 1998;23:385
5，Bürgi E. Die Arzneikombinationen. Julius Springer Verlag, 1938
6，Yu R, Ticku MK. Effects of chronic pentobarbital treatment on the GABA A receptor complex in mammalian cortical neurons. J Pharmacol Exp Ther,1995; 275:1442
2000-02-28 received, 百拇医药
单位：于榕 姚明辉(上海医科大学基础医学院药理教研室，上海 200032)
关键词：四氢孕酮；苯巴比妥；惊厥；最大电休克实验；印防己；ED50
中国临床药理学与治疗学000201
目的 观察四氢孕酮对不同动物惊厥模型的保护作用。方法 C57小鼠腹腔注射四氢孕酮15 min 后观察其对最大电休克实验(maximal electrical seizure, MES)或印防己所致惊厥的保护作用。结果 在MES试验， 四氢孕酮或苯巴比妥产生剂量依赖性的保护作用。苯巴比妥的ED50为2.40 mg.kg-1, 95%可信限为1.22至4.72 mg.kg-1。四氢孕酮的ED50为0.086 mg.kg-1, 95%可信限为0.037至0.201 mg.kg-1，显著较苯巴比妥强(P<0.01)。 四氢孕酮对印防己所致惊厥保护作用 的ED50为0.12 mg.kg-1。两药各1/2 ED50量的联合用药在MES试验产生80%的保护作用，高于50%。提示四氢孕酮和苯巴比妥具协同抗惊厥作用。在印防己致惊厥试验， 四氢孕酮亦产生剂量依赖性保护作用， ED50为0.123 mg.kg-1，95%可信限为0.085至0.263 mg.kg-1。结论腹腔注射四氢孕酮对MES或印防己所致惊厥具有剂量依赖性的保护作用；对MES， 四氢孕酮的保护作用显著大于苯巴比妥，并与后者有协同作用。
, http://www.100md.com
中图分类号 R965
Protective effects of allopregnanolone
against different seizure models in mice
YU Rong
(Department of Pharmacology, Shanghai Medical University,Shanghai 200032)
YAO Ming-Hui
(Department of Pharmacology, Shanghai Medical University,Shanghai 200032)
, http://www.100md.com
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.
, http://www.100md.com
Key words allopregnanolone; phenobarbital; seizure; maximal electrical seizure; picrotoxin; ED50
Neurosteroids are endogenous metabolites of certain steroid hormones that rapidly alter the excitability of neurons by direct actions on ligand-gated ion channels[1].Specifically,the endogenous 3α-hydroxyl ring A-reduced metabolites of progesterone,allopregnanolone produced a powerful enhancement of GABAA receptor- mediated responses in vitro by interaction with unique non-genomic recognition site on the GABAA receptor complex that is distinct from the benzodi-azepine, barbiturate, and GABA recognition sites[2,3].
, http://www.100md.com
Allopregnanolone has been proposed as putative anticonvulsant compound due to its ability to enhance GABAA-mediated neurotransmission[4].The γ-aminobutyric acid (GABAA) receptor Cl- channel complex is a major target for the action of therapeutically useful drugs such as benzodiazepines (BZD) and barbiturates that elicit at least some of their anticonvulsant effects via the GABAA receptor in the central nervous system. Considering the fact that the neurosteroids have their distinctive recognition site on the GABAA receptor complex,we therefore hypothesized that neurosteroids have anticonvulsant activity and their anticonvulsant profile might be different from that of benzodiazepines or barbiturates.Consequently, in the present study, we examined the protective effect of allopregnanolone against seizure on different animal models and compare to that of phenobarbital.
, 百拇医药
1 Material and method
1.1 Animals Male C57 mice (18～22 g) were obtained from animal department of Shanghai Medical University.Approved number 02～229. Animals were allowed to acclimatize with free access to food and water for a 48 h period before testing.
1.2 Drugs Allopregnanolone was purchased from Sigma Chemical Co.(St Louis,MO.USA). Stock solution of allopregnanolone was prepared in dimethyl sulfoxide (SP Jinshan Chemical Plant,Lot 790917) and further dilution was made using 0.9% saline. Phenobarbital was obtained from Shanghai Xinya Pharmaceutical Factory, Lot 860425-C2.All drug solutions were administered ip in a volume equaling 1% of the animal's body weight.
, http://www.100md.com
1.3 MES-induced seizure test Evaluations were carried out in a quiet,temperature controlled room(23 °C).Animals were fasted over- night and brought in the room 4 hours prior to experiment. Mice were injected intraperitoneally (ip) with different doses of phenobarbital and allopregnanolone 15 minutes before the MES test. Multifunctional Physiology Stimulator (Jialong Medical Instrument Co, Ltd.) was applied for stimulation (wave duration: 0.3 ms). Stimulating electrodes were placed on the mice cornea. Normal saline was used wet the electrode to guarantee the contact. Animals were observed right after the stimulation. Tonic extension was positive response. Stimulating parameter of voltage was adjusted to make all the mice to have positive responses before any treatment.
, http://www.100md.com
1.4 Picrotoxin-induced seizure test Mice were injected intraperitoneally (ip) with different doses of allopregnanolone or vehicle and 15 minutes later received a ip injection of the picrotoxin at dose of 5.5 mg.kg-1 . In the preliminary study, we found that this dose of picrotoxin could induce tonic seizure in 100 % of the mice within 15 minutes after the picrotoxin administration. Animals were observed for 15 minutes to record the number of mice showing tonic extension right after the picrotoxin administration.
, 百拇医药
1.5 Data analysis To construct dose-effect curves, allopregnanolone or phenobarbital was tested at several doses spanning the dose producing 50 % protection. At least 10 mice were tested at each dose. ED50 values and their 95% confidence intervals were determined by log-probit analysis using Bliss method. Comparison the ED50 values was analyzed using u test. In picrotoxin test, mice failing to show seizures 15 minutes after picrotoxin administration were scored as protected. Combination study was analyzed using Bürgi method [5].
, 百拇医药
2 Results
2.1 Protective activity of allopregnanolone in maximal electroshock seizure (MES) test Allopregnanolone was compared to phenobarbital for their protective activities in the maximal electroshock seizure test.Pretreatment with the phenobarbital 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. Pretreatment with the allopregnanolone also produced a dose-dependent protective effect against seizure. 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).Also the combination of phenobarbital and allopregnanolone was examined on its protective activity against seizure. Half ED50 values of phenobarbital and allopregnanolone were combined. This combination showed a 80% of protection, which was higher than 50% produced by either phenobarbital or allopregnanolone at their ED50 values respectively.
, 百拇医药
Tab 1 Comparison of the protective effects of allopregnanolone and phenobarbital on the maximal electroshock seizure in C57 mice Group
ED50/mg.kg-195%
confidence interval
Allopregnanolone
0.086**
0.037~0.201
Phenobarbital
, http://www.100md.com
2.40
1.22~4.72
Allopregnanolone group mice were administered with 0.01, 0.05, 0.1,0.5 and 1.0 mg.kg-1 of allopregnanolone, ip.Phenobarbital group mice were administered with 0.5, 1.0, 5.0,10 and 50 mg.kg-1 of phenobarbital injection, ip.At least 10 mice were tested at each dose. ED50 values and their 95% confidence intervals were determined by log-probit analysis using Bliss method. Comparison between the ED50 values was analyzed with u test. ** P<0.01
, http://www.100md.com
Fig 1 Dose-response relationship of allopregnanolone for the protection against picrotoxin-induced seizure
C57 mice were administered with 0.01, 0.05, 0.1, 0.5 and 1.0 mg.kg-1 of allopregnanolone, ip. 10 mice were tested at each dose. ED50 values and their 95% confidence intervals were determined by log-probit analysis using Bliss method. Mice failing to show seizures 15 minutes after picrotoxin administration were scored as protected.
, 百拇医药
2.1 Protective activity of allopregnanolone in picrotoxin seizure test Allopregnanolone was examined for protective activity in the picrotoxin seizure test. As illustrated in Fig 1,pretreatment with the allopregnanolone produced a dose- dependent protective effect against picrotoxin -induced seizure.The potency (ED50 value) 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.
, 百拇医药
Therefore, allopregnanolone administration had a protective activity against different seizures in MES and picrotoxin tests with a dose- dependent manner.Also,allopregnanolone had a higher potency than phenobarbital,and there was a synergistic action between allopregnanolone and phenobarbital.
3 Discussion
Several lines of recent investigation have shown that neurosteroid allopregnanolone allosterically modulate GABAergic transmission through a unique binding site on the GABA A receptor Cl- channel complex. This binding site has been found to be distinctly different from that of the benzodiazepines or the barbiturates site, respectively. In particular, the 3α-hydroxyl ring A-reduced metabolite of progesterone, allopregnanolone produced a potent enhancement of GABA A receptor responses in vitro. Since benzodiazepines or barbiturates were believed to produce anticonvulsant activity via the binding to the GABA A receptor complex, it was reasonable to speculate that allopregnanolone has a similar anticonvulsant activity like benzodiazepines or barbiturates. However, neurosteroids had their distinctive recognition site on the GABA A receptor complex, we therefore compared the protective effects of allopregnanolone and phenobarbital against seizures in MES and picrotoxin tests.
, http://www.100md.com
We found that either phenobarbital or allopregnanolone produced a dose-dependent protective effect against seizure in MES test. The ED50 value allopregnanolone was significantly smaller than that of phenobarbital. In other words, allopregnanolone had a higher potency than phenobarbital in preventing seizure. The combination study showed that there was a synergism between phenobarbital and allopregnanolone in their anticonvulsant activities. These results were consistent with the results from our previous ligand binding study on the primary cortical neuron, in which neurosteroid showed a higher potency than barbiturate [6]. It also suggested that the neurosteroid had a potential to be used alone or combined with other drugs, such as benzodiazepines or barbiturates, to treat epilepsy clinically. By doing so, the side effects of currently used drugs for epilepsy could be avoided since neurosteroids were endogenous in nature. In the picrotoxin test, we found pretreatment with the allopregnanolone also produced a dose-dependent protective effect against picrotoxin-induced seizure. This result support the finding of the MES test.
, 百拇医药
In conclusion, these results have demonstrated that allopregnanolone was more potent than phenobarbital in protecting against different seizures.
Yu Rong, male, 35 years old, Ph.D, associate professor, neuropharmacology
References
1，Paul SM, Purdy RH. Neuroactive steroids . FASEB J,1992; 6:2311
2，Majewska MD. Neurosteroids: endogenous bimodal modulators of GABAA receptor. Mechanism of action and physiological significance.Prog Neurobiol, 1992;38:379
, 百拇医药
3，Ticku MK.Drug modulation of GABAergic transmission. Sem Neurosci, 1991;3:211
4，Frye CA, Reed TA. Androgenic neurosteroids: antseizure effects in an animal model of epilepsy. Psy-choneuroendocrinology, 1998;23:385
5，Bürgi E. Die Arzneikombinationen. Julius Springer Verlag, 1938
6，Yu R, Ticku MK. Effects of chronic pentobarbital treatment on the GABA A receptor complex in mammalian cortical neurons. J Pharmacol Exp Ther,1995; 275:1442
2000-02-28 received, 百拇医药