Compelling evidence has shown a pivotal role of dopaminergic function in drug addiction. Recently, the lateral habenula (LHb) has attracted a great deal of attention as another target for abused drugs in the brain because its role in... more
Compelling evidence has shown a pivotal role of dopaminergic function in drug addiction. Recently, the lateral habenula (LHb) has attracted a great deal of attention as another target for abused drugs in the brain because its role in regulating dopaminergic system, among others. GABA and glycine are major inhibitory neurotransmitters. Their corresponding receptors are key targets of ethanol. The properties of these receptors in LHb neurons and their responses to ethanol in particular however, remain unknown. Using the patch clamp techniques, we examined the effects of ethanol on the chloride currents elicited by GABA and glycine in LHb neurons acutely dissociated from 10-20 day-old Sprague–Dawley rats. We show that GABA concentration-dependently elicited a bicuculline sensitive inward current in 96% (130/140) of the neurons tested. Ethanol (43.2 mM) suppressed current elicited by a wide range of concentrations (1-300 μM) of GABA in 74% (35/47) cells tested. Ethanol suppression is de...
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The ventrolateral preoptic nucleus (VLPO) plays a critical role in regulating and maintaining sleep-awake cycle. It receives both excitatory and inhibitory inputs and regulates the activity of tuberomamillary nucleus and other... more
The ventrolateral preoptic nucleus (VLPO) plays a critical role in regulating and maintaining sleep-awake cycle. It receives both excitatory and inhibitory inputs and regulates the activity of tuberomamillary nucleus and other monoaminergic nuclei, which in turn determines the alternation between wakefulness and non-rapid eye movement sleep. Although a previous study has shown that systematic administration of GABAergic anesthetic agents activated VLPO neurons, which is believed to be responsible for the sedative effects of these agents, it is unknown whether a direct administration of γ-Aminobutyric acid (GABA) into the VLPO can induce sedation. Here we report that rats that received intra-VLPO infusion of GABA demonstrated sustained reduction in locomotion, most significantly during the 10-40th min period after infusion. Conversely, rats that received intra-VLPO infusion of noradrenaline demonstrated a sustained increase in locomotion from 20th min after infusion. By contrast, no appreciable change was observed in rats that received intra-VLPO infusion of glycine. This result demonstrates that exogenous GABA may activate sleep-active neurons in the VLPO and promote sedation.