GABA(C) receptors (GABA(C)Rs) are widely expressed in the mammalian subcortical visual system, particularly in the retina and superior colliculus (SC). GABA(C)Rs are composed of specific rho1-3 subunits the expression of which varies among visual structures. Thus rho1 subunits are most abundant in retina, and their loss eliminates GABA(C)R expression and function. In the SC, rho2 subunit expres...

The genetically epilepsy-prone rat (GEPR) is a unique animal model of seizure predisposition with substrains (i.e., GEPR-NE, GEPR-3, and GEPR-9) that exhibit different seizure patterns in response to the same stimulus. Among many deficits identified in these animals, reduced responses to GABA(A) receptor agonists have been described in several brain regions of the GEPR-9. However, few studies h...

In certain Aplysia neurons, glutamate, GABA, and acetylcholine (ACh) all elicit desensitizing Cl-dependent responses. This fact and the finding that the glutamate and GABA responses "cross-desensitize" led to the suggestion (Swann and Carpenter, 1975; King and Carpenter, 1987) that the responses to these transmitters were mediated by the same receptor-channel complex. This hypothesis is incompa...

The receptor pharmacology of cholinergic ("starburst") amacrine cells was studied in a newly developed rabbit retinal slice preparation with whole-cell patch clamp. Displaced starburst cells were labeled with the fluorescent dye 4,6-diamidino-2-phenylindole (DAPI), and their dendritic morphology was identified in the slice with Lucifer yellow. Under conditions in which synaptic transmission was...

The hippocampus contains one very strong recurrent excitatory network formed by associational connections between CA3 pyramidal cells and another that depends largely on a disynaptic excitatory pathway between dentate granule cells. The recurrent excitatory network in CA3 has long been considered a possible location of autoassociative memory storage, whereas changes in the level and arrangement...

Pavlovian stimuli can markedly elevate instrumental responding, an effect known as Pavlovian-instrumental transfer (PIT). As the role of the ventral tegmental area (VTA) in PIT is yet unknown, we examined the effects of transient VTA inactivation by direct microinjections of a mixture of the GABA(A) and GABA(B) receptor agonists, muscimol and baclofen. Results reveal that PIT, i.e., the increas...

The regulation of glutamate (Glu) release from the excitatory input to dopamine cells in the ventral tegmental area (VTA) during acute withdrawal from morphine was studied in slices from animals treated for 6-7 d with morphine. EPSCs were inhibited by opioid agonists acting at micro-subtype receptors but not by selective delta- or kappa-subtype agonists. The opioid inhibition was reduced by 65%...

Although -aminobutyric acid type A receptor agonists and antagonists bind to a common site, they produce different conformational changes within the site because agonists cause channel opening and antagonists do not. We used the substituted cysteine accessibility method and two-electrode voltage clamping to identify residues within the binding pocket that are important for mediating these diffe...

In this review, we present evidence for the role of g-aminobutyric acid (GABA) neurotransmission in cerebral ischemia-induced neuronal death. While glutamate neurotransmission has received widespread attention in this area of study, relatively few investigators have focused on the ischemia-induced alterations in inhibitory neurotransmission. We present a review of the effects of cerebral ischem...