t-[35S]butylbicyclophosphorothionate binding under equilibrium and nonequilibrium conditions: differential effects of barbiturates and gamma-aminobutyric acid in the long-sleep and short-sleep selected mouse lines

GABAergic and dopaminergic transmission in the brain of Roman high-avoidance and Roman low-avoidance rats

The GABAergic and dopaminergic pathways in the central nervous system (CNS) play a pivotal role in the control of emotions and in the adaptive responses to stressful stimuli. The present study was aimed at characterizing a range of biochemical markers of GABA- and dopamine-mediated neurotransmission in the CNS of Roman high-avoidance (RHA/Verh) and Roman low-avoidance (RLA/Verh) rats, two psychogenetically selected lines that differ in their level of emotionality. The stimulatory effect of GABA on 36Cl- uptake was less pronounced in the cerebral cortex of RLA/Verh rats as compared to RHA/Verh rats, whereas no line-related changes were detected in [3H]GABA and [3H]flunitrazepam binding. On the other hand, the density of D1 dopamine receptors labeled with [3H]SCH 23390 was lower in the nucleus accumbens of RLA/Verh rats as compared to their RHA/Verh counterparts, whilst no line-dependent changes were observed in the binding parameters of D1 dopamine receptors in the striatum, amygdala, and prefrontal cortex. These biochemical differences may contribute to the distinct emotionality and responsiveness to the effects of psychoactive drugs of RHA/Verh and RLA/Verh rats.

Solubilization of benzodiazepine receptors from long- and short-sleep mice

Previous studies have shown that long-sleep (LS) and short-sleep (SS) mice, which were selectively bred for differential responses to the sedative-hypnotic actions of ethanol, also differ in response to several other agents that act at the GABAergic receptor. Binding at cortical benzodiazepine receptors is enhanced differentially by GABA and ethanol in membranes prepared from the two lines of mice with SS receptors enhanced to a greater extent. Heat denaturation studies and other biochemical characterizations of these receptors suggest that the GABAergic receptor complex from the two lines of mice differs. The present study examined whether perturbation of receptor-membrane interactions by treatment with detergent altered either GABA enhancement of [3H]flunitrazepam binding or ethanol enhancement of this binding. Octylglucopyranoside (OCTG), 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS), or deoxycholate solubilization of cortical membranes resulted in a loss of the LS/SS difference in GABA enhancement. Ethanol's effects on binding were altered differently from those of GABA by treatment with OCTG as an increase, not a decrease, in enhancement was observed in both lines of mice. These results suggest that protein-membrane interactions play an important role in mediating LS/SS differences in the allosteric interactions within the GABAergic receptor complex.