Ethanol-Induced Plasticity of GABAA Receptors in the Basolateral Amygdala

Acute and chronic ethanol (EtOH) administration is known to affect function, surface expression, and subunit composition of γ-aminobutyric acid (A) receptors (GABA(A)Rs) in different parts of the brain, which is believed to play a major role in alcohol dependence and withdrawal symptoms. The basolateral amygdala (BLA) participates in anxiety-like behaviors including those induced by alcohol withdrawal. In the present study we assessed the changes in cell surface levels of select GABA(A)R subunits in the BLA of a rat model of alcohol dependence induced by chronic intermittent EtOH (CIE) treatment and long-term (>40 days) withdrawal and investigated the time-course of such changes after a single dose of EtOH (5 g/kg, gavage). We found an early decrease in surface expression of α4 and γ subunits at 1 h following single dose EtOH treatment. At 48 h post-EtOH and after CIE treatment there was an increase in α4 and γ2, while α1, α2, and γ surface expression were decreased. To relate functional changes in GABA(A)Rs to changes in their subunit composition we analyzed miniature inhibitory postsynaptic currents (mIPSCs) and the picrotoxin-sensitive tonic current (I(tonic)) 48 h after EtOH intoxication. The I(tonic) magnitude and most of the mIPSC kinetic parameters (except faster mIPSC decay) were unchanged at 48 h post-EtOH. At the same time, I(tonic) potentiation by acute EtOH was greatly reduced, whereas mIPSCs became significantly more sensitive to potentiation by acute EtOH. These results suggest that EtOH intoxication-induced GABA(A)R plasticity in the BLA might contribute to the diminished sedative/hypnotic and maintained anxiolytic effectiveness of EtOH

AQP5 Is Expressed In Type-B Intercalated Cells in the Collecting Duct System of the Rat, Mouse and Human Kidney

We screened human kidney-derived multipotent CD133+/CD24+ ARPCs for the possible expression of all 13 aquaporin isoforms cloned in humans. Interestingly, we found that ARPCs expressed both AQP5 mRNA and mature protein. This novel finding prompted us to investigate the presence of AQP5 in situ in kidney. We report here the novel finding that AQP5 is expressed in human, rat and mouse kidney at the apical membrane of type-B intercalated cells. AQP5 is expressed in the renal cortex and completely absent from the medulla. Immunocytochemical analysis using segment- and cell type-specific markers unambiguously indicated that AQP5 is expressed throughout the collecting system at the apical membrane of type-B intercalated cells, where it co-localizes with pendrin. No basolateral AQPs were detected in type-B intercalated cells, suggesting that AQP5 is unlikely to be involved in the net trans-epithelial water reabsorption occurring in the distal tubule. An intriguing hypothesis is that AQP5 may serve an osmosensor for the composition of the fluid coming from the thick ascending limb. Future studies will unravel the physiological role of AQP5 in the kidney