The largest component in the fully dark-adapted ERG is a corneal-positive response, known as the b-wave, and believed to originate from depolarizing (ON-type) bipolar cells. The two types of GABA receptors, GABA(A) and GABA(C) have been reported to exist on bipolar cells in rat retina. The goal of these experiments was to find whether these GABA receptors participate in the generation of the b-...

GABA(A) receptors are the principal sites of fast synaptic inhibition in the brain. These receptors are hetero-pentamers that can be assembled from a number of subunit classes: alpha(1-6), beta(1-3), gamma(1-3), delta(1), epsilon, theta;, and pi, but the majority of receptor subtypes is believed, however, to be composed of alpha, beta, and gamma2 subunits. A major mechanism for modulating GABA(...

At the axon terminal of goldfish retinal bipolar cells, GABA(C) receptors have been shown to mediate inhibitory reciprocal synaptic currents. Here, we demonstrate a novel standing GABAergic current mediated exclusively by GABA(C) receptors. Selective inhibition of GAT-1 GABA transporters on amacrine cells increases this tonic current and reveals a specific functional coupling between GAT-1 tran...

GABA(B) (gamma-aminobutyric acid type B) receptors are important for keeping neuronal excitability under control. Cloned GABA(B) receptors do not show the expected pharmacological diversity of native receptors and it is unknown whether they contribute to pre- as well as postsynaptic functions. Here, we demonstrate that Balb/c mice lacking the GABA(B(1)) subunit are viable, exhibit spontaneous s...

Serotonergic neurotransmission in prefrontal cortex (PFC) has long been known to play a key role in regulating emotion and cognition under normal and pathological conditions. However, the cellular mechanisms by which this regulation occurs are unclear. In this study, we examined the impact of serotonin on GABA(A) receptor channels in PFC pyramidal neurons using combined patch-clamp recording, b...

Glutamate release at bipolar to ganglion cell synapses activates NMDA and AMPA/kainic acid (KA) ionotropic glutamate receptors. Their relative strength determines the output signals of the retina. We found that this balance is tightly regulated by presynaptic inhibition that preferentially suppresses NMDA receptor (NMDAR) activation. In transient ON-OFF neurons, block of GABA and glycine feedba...

GABA receptors (GABA(A)) are the major sites of fast synaptic inhibition in the brain and can be assembled from five subunit classes: alpha, beta, gamma, delta, and epsilon. Receptor function can be regulated by direct phosphorylation of beta and gamma2 subunits, but how kinases are targeted to GABA(A) receptors is unknown. Here we show that protein kinase C-betaII (PKC-betaII) is capable of di...

We investigated the localization of GABA(A) and GABA(C) receptors in horizontal cells (HCs) and HC axon terminals (ATs) dissociated from goldfish retina, using whole-cell patch-clamping recordings. Applications of GABA on HCs induced two groups with inward currents at the holding potential of -50 mV: One was a sustained inward current in the H1 cell, with one type of HCAT (AT1), and the other w...

Assembly of fully functional GABA(B) receptors requires heteromerization of the GABA(B(1)) and GABA(B(2)) subunits. It is thought that GABA(B(1)) and GABA(B(2)) undergo coiled-coil dimerization in their cytoplasmic C termini and that assembly is necessary to overcome GABA(B(1)) retention in the endoplasmatic reticulum (ER). We investigated the mechanism underlying GABA(B(1)) trafficking to the ...

Effects of GABA-ergic agonists and antagonists were examined on the melanophores of a carp C. mrigala in vitro. GABA and baclofen both induced concentration - related dispersion in fish melanophores. Denervation of the melanophores by reserpine treatment potentiated the sensitivity of the melanophores to GABA. While denervation by cooling treatment inhibited the sensitivity of the melanophores ...