R. Shingai et al., MODULATION OF IONIC CURRENTS THROUGH GABA(A) RECEPTOR SUBTYPES BY ENDOGENOUS STEROIDS, Japanese Journal of Physiology, 44, 1994, pp. 137-140
GABA(A) receptors were expressed in Xenopus oocytes by injecting messe
nger RNAs from chick retina and chick cortex, and the potency of 3 alp
ha-hydroxy-5 alpha-pregnan-20-one (3 alpha-OH-DHP) and 5 alpha-pregnan
e-3 alpha, 21-diol-20-one (THDOC) was investigated by electrophysiolog
y under voltage clamp conditions. For the receptors of chick retina, 3
alpha-OH-DHP (100 nM) and THDOC (100 nM) augmented GABA actions (peak
current) 1.6 times (n=6) and 1.5 times (n=7), respectively. The curre
nts induced by 0.3-10 mu M GABA for the receptors of the chick retina
were sensitive to bicuculline, petobarbital, and diazepam. GABA(A) rec
eptors in the chick retina in vivo as well as the receptors in the bra
in may be functionally modulated by endogenous steroids.