GABA A 47 (6) : , (Orchinik et al., 1994), ( benzodi2. mmol/ L Tris2HCl , 3. ( kainic acid, KA ) ( preg2 (, 1997 ; 1998), Sigma,

Transcription

1 47 (6) : , 2001 A cta Zoologica S inica 3 GABA A ) ) (, (, 3 ( KA),, ( Pe) ( Pes) 2 ( GABA A ), Pe 3 H2GABA GABA A, ( P < 0105 P < 01001), ( P > 0105) Pe GABA A ( Pic), KA Pes GABA A ( P < 0101 P < 01001), :, GABA A GABA A A,, 25 g, GABA A, 112 (Orchinik et al., 1994), ( benzodi2 (p H 711), (215 gppo, 0125 azepine, BZP), GABA g POPOP/ 500 ml),,,,,, 3 H2GABA ( 30 ci/ mol, ( Majewska, 1992), 1 mci/ ml), ( kainic acid, KA ) ( preg2, nanolone, Pe) ( pregnanolone GABA A (, 1997 ; 1998), Sigma, GABA A 113,, KA (4 mg/ ml, 10 / g ), 3 H2GABA GABA A,, GABA A, GABA A (i. c. ) (i. c. v. ) (, 6, 1) 30 min ( KA mol/ L, 50 mmol/ L Tris2HCl sulfate, Pes) (picrotoxin, Pic) 111, (1997) ( ), GABA A ),, , (No ) 33 E2mail : edu. cn,, 38, : E2mail : net

2 6 : GABA A 1 Table 1 The dose of drugs and the way of injection 649 Group Way of injection (g/ ) Doses(g/ body weight) (Control group) i. c. 10 l (019 %NaCl) KA ( KA group) i. c mg ( KA) Pe ( Pe group) i. c. 7 g ( Pe) Pe + KA ( Pe + KA group) i. c. 7 g ( Pe), 0104 mg ( KA) Pes ( Pes group) i. c. 7 g ( Pes) Pes + KA ( Pes + KA group) i. c. 7 g ( Pes), 0104 mg ( KA) Pic ( Pic group) i. c. v. 013 g ( Pic) / Pe + Pic ( Pe + Pic group) i. c. + i. c. v. 7 g ( Pe), 013 g ( Pic) Pes + Pic ( Pes + Pic group) i. c. + i. c. v. 7 g ( Pes), 013 g ( Pic) H2GABA GABA A, 20 min, 019 ml, 100 l 011 mol/ L 3 H2GABA,,, Pe + Pic 3 H2GABA,, Pes + Pic, 100 l 212 GABA A (3 1) min 2 ml, 1 ml GABA A,, PACKARD22000 ( : F (8,45) = 712, P < 0101 ; dpm : F (8,45) = 714, P < 0101 ; : F (8,45) = Bradford, 914, P < 0101 ; : F (8,45) = 414 ; P < 0101) (BSA), 21212, KA, 5 min ( 595 nm) GABA A 3 H2GABA, (mg / ml) ( t2test : t = 617 ; t = 616 ; t = dpm, 614 ; t = 410, n 6, P < 0105 P < 3 H2GABA GABA A (p mol/ 0101) ( 1) mg ), 6, 21213, Pe GABA A 3 H2GABA, (ANOVA), ( t2test, t , ( F, n 6, P < 0105 P < 01001), ), t2 ( ) ( P < 0105 ( t2test, t = 0112, n = 6, P > 0105), P < 0101 ) Pe + KA 3 H2GABA, 2 KA ; Pic H2GABA ( t2test, t = 111, n = 6, P > 0105), ( t2test : t 211 = 617, t = 618, t = 618, n 6, P KA, < 0101 P < 01001) ( 1), 30 min 21214, Pes Pes + KA ; Pe Pe + KA 3 H2GABA ( t2test : t,,, = , t = , t = 313 ; Pes,,, 813, t = , n 6, P <, ; Pes + KA 0101 P < 01001) Pes + KA

3 H2GABA GABA A Fig. 1 Effects of drugs on the binding of 3 H2GABA to GABA A receptor in different brain areas of mice A. ( Hypothalamus) B. (Cerebral cortex) C. ( Hippocampus) D. (Cerebellum) 3 P < P < P < Student s t2test n = 6 (Compared with control group) # P < 0105 # # P < 0101 # # # P < Student s t2test n = 6 KA (Compared with KA group) 2 ( Pic) Pe 3 H2GABA GABA A Fig. 2 Effect of picrotoxin on pregnanolone modulation of the binding of 3 H2GABA to GABA A receptors in different brain areas of mice P < P < P < Student s t2test n = 6 Pe (Compared with Pe group) Pes, 0105) ( 1) ( t2test : t = 717, , n 6, P < KA, Pes + KA P < 01001), ( t2test : t = GABA A KA, 115, n = 6, P > 0105) ( 1) ( t2test : t = 1111, n = 6, P < KA, Pe + KA 3 H2GABA 01001) KA ( t2 KA, test : t = , n 6, P > 0105) ( ( t2test : t = 216, n = 6, P < 0105), 1) KA, Pe, Pe + Pic GABA A ( t2test : t = 219, n = 6, P < 0105), ( t2test : t = 1314, ( t2test : t = 210, n = 6, P > t = 1013, t = 4013, t = 1112, n

4 6 : GABA A ( Pic) Pes 3 H2GABA GABA A Fig. 3 Effect of picrotoxin on pregnanolone sulfation modulation of the binding of 3 H2GABA to GABA A receptors in different brain areas of mice 3 : P < : P < : P < Student s t2test n = 6 Pes (Compared with Pes group) # : P < 0105 # # : P < 0101 # # # : P < Student s t2test n = 6 Pic (Compared with Pic group) 6, P < 01001), Pe + Pic Pic GABA A ( t2test : t = 215, t = 019, t = 215, t = 019, 0105) ( 2) n 6, P > Pes, Pes + Pic GABA, Caba (1994) GABA A, Pe + KA, GABA A ( t2test : t = 313, , n 6, P < 0105, P < 01001), GABA A KA, Pe KA, Pes + Pic GABA A Pe GABA A Pic, ( t2test : t = 918 Pic Pe, GABA A 910, n 6, P < 01001) ( 3) 3, Pic Pe GABA A,, Pe, GABA A Pe + KA GABA A (Rupprecht et al., 1993) KA, KA, GABA A Sieghart (1995) GABA A ( GRC) /,, GRC (Sousa et al., 1997), ( ) 5 / 5 A, 3 C 17, KA GABA A Pe, GABA A, Pe, Pic, Pic Pe GABA A, Pe Pic (, 1997), Cl -, C 20, GABA A, Pe GABA A,, GABA A, GABA ( Caba et al., 1994) BZP BB ( ), 5 2THP ( Pe) Pes, GABA A GABA A (Frye et al., 1994), Pe BB, KA, GABA GABA A, GABA A KA GABA Cl -,, Friedman (1994) KA

5 ( Majewska et al., Pes, GABA A 1987), Pes, ( Prince et al., Pe, 1992) Pes, GABA A Pe, Pes Pe, Pes GABA GABA A,, GABA A Cl -, Cl - (Orchinik et al., 1994),, GABA A GABA A Pe, Cl - Pes + KA KA,, 70 GABA A Pes,, Pes Pe, Pic, Pes GABA A, GABA A, Pes GABA A Pes GABA A,, Pes GABA A,,! ( References) Caba, M., M. G. Gonzalez and C. Beyer 1994 Perispinal progestins enhance the antinociceptive effects of muscinol in the rat. Pharmacol. Biochem Behave. 47 (1) : Friedman, L. K., D. E. Pellegrinr2Giampietro and E. F. Sperber 1994 Kainate2induced status epilepticus alters glutamate and GABA A receptor gene expression in adult rat hippocampus : on i n sit u hybridization study. J. Neurosci. 14 (5) : Frye, C. A. and E. A. Leadbetter reduced progesterone metabolites are essential in hamster vita for sexual receptivity. L if e Sci. 54 (10) : Liu, H. Z., X. D. Zhang and J. Q. Zhu 1997 The effect of progesterone on the binding of [ 3 H] 2GABA to GABA A receptor in different brain ar2 eas ovary and uterus in mice. J. N anji ng. U niv. 33 (2) : [,, 1997 [ 3 H] 2GABA GABA A. 33 (2) : ] Liu, H. Z., X. D. Zhang and J. Q. Zhu 1998 Effect of progesterone on 3 H2 2GABA accumulation in slices of mouse brain. Acta Zool. Sin. 44 (2) : [,, H (2) : ] Majewska, M. D. and R. D. Schwartz 1987 Pregnenolone2sulfate : an endogenous antagonist of the 2aminobutyric acid receptor complex in brain? B rai n Res. 404 : Majewska, M. D Neurosteroids : endogenous bimodal modulators of the GABA A receptor. Mechanism of action and physiological signifi2 cance. Prog. Neurobiol. 38 : Orchinik, M. and T. F. Murray 1994 Steroid modulation of GABA A receptors in an amphibian brain. B rai n Res. 646 (2) : Prince, R. J. and M. A. Simmonds Pregnan23 2ol2202one, a specific antagonist at the neurosteroid site of the GABA A receptor2complex. Neurosci. Letterv. 135 : Rupprecht, R., M. Johannes, H. M. Reull and T. Trapp 1993 Progesterone receptor2mediate effects of neuroactive steroids. Neuron. 11 : Sieghart, W Structure and pharmacology of 2aminobutyric acid receptor subtypes. Pharmacol. Rev. 47 (2) : Sousa, A. and K. M. Ticku 1997 Interactions of the neurosteroid dehydroepiandrosterone sulfate with the GABA A receptor complex reveals that it may act via the picrotoxin site. J. Pharmacol. Ex p. Ther. 282 (2) :

6 6 : GABA A 653 ( Abstract) MOD ULATION OF GABA A RECEPTORS BY PREGNENOLONE AND PREGNENOLONE SUL FATE IN MOUSE BRAIN D URING CONVULSION 3 ZHOU Xue2Rui ( Depart ment of Biology, Huaiyi n Teacthers College, Huaiyi n , Jiangsu, China) L I Xiao2Yu ZHU Jian2Qin 3 ( Depart ment of Biological Science and Technology, N anji ng U niversity, N anji ng , Chi na) Recent investigation shows the regulation of GABA A receptor by neurosteroids in mammalian brain. Though progesterone can be used as psychotropic drug via its interaction with GABA A receptor, the role of pregnenolone ( Pe) and pregnenolone sulfate ( Pes) remains unclear. To f urt her elucidated neurosteroids on t he modulation of GABA A receptor, we investigated the effect of Pe and Pes on the 3 H2GABA binding to the GABA A receptors in hypot halamus, cerebral cortex, hippocampus and cerbellum in mice using a convulsion model induced by kainic acid. The results showed that Pe increased the binding of 3 H2GABA to the GABA A receptors in the tested brain areas. The increase of binding in t he hypot halamus, hippocampus and cerebellum was significant ( P < 0105 or P < 01001), but t he inerese of binding in cerebral cortex was not significant ( P > 0105). The modulation effect of Pe on GABA A receptors was blocked by picrotoxin, and consequently the kainic acid2induced convulsion was inhibited. On the other hand, Pes markedly decreased the binding of the 3 H2GABA to GABA A receptors ( P < 0101 or P < 01001) in all of t he tested brain areas and enhanced t he potency of kainic acid2induced convulsive. These result s suggest t hat Pe had marked sedative and anti2convulsion effect s, which were probably mediated by the GABA A receptors. Key words Mouse, GABA A receptor, Pregnenolone, Pregnenolone sulfate, Kainic acid, Picrotoxin 3 This work was supported by National Natural Science Foundation of China (No ) 33 Corresponding author. E2mail : edu. cn