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Abstract: Cholinergic modulation of spontaneous GABAergic currents (mIPSC) was studied using whole-cell patch methods in mouse accessory olfactory bulb slices. Carbachol (above 100µM) administration produced an increase in the mIPSC frequency in mitral cells, but did not affect the responses of mitral cells to GABA. The carbachol effect persisted in the presence of combined ionotropic and metabotropic glutamatergic receptor antagonists. The carbachol effect was reduced by the muscarinic receptor type-1 and -4 (M1 and M4) antagonist pirenzepine (10µM), but not by the M2 and M4 antagonist himbacine (10µM). The KCNQ/Kv7 potassium channel openers retigabine (80µM) and diclofenac (300µM) blocked the carbachol action, while the KCNQ potassium channel blocker XE-911 (20µM) increased the mIPSC frequency. XE-911''s action persisted in the presence of glutamate receptor blockers. In the presence of carbachol, mIPSCs were abolished by Ni (200µM), while being insensitive to the calcium channel blocker nimodipine (30µM), suggesting a role for R-type calcium channels in the GABA release. These results suggest that carbachol closed KCNQ channels by stimulating M1 receptors on granule cell dendrites, and the resulting depolarized and unstable membrane promoted calcium influx, thus increasing the GABA release. The possible role of acetylcholine in facilitating formation of a pheromone memory in mice is also discussed. [Copyright &y& Elsevier]

• Venus fluorescent cells in the dl BST were CRH neurons in CRF-Venus ΔNeo mice. • Voltage-clamp was applied to investigate CRH neurons in the dl BST after formalin injection. • Formalin increased the frequency of mEPSCs in CRH neurons only in females. • In both males and females, mIPSCs in CRH neurons were not changed after formalin injection. • Interphase in formalin test increased synaptic input to CRH neurons of the dl BST in females. We earlier reported female-biased, sex-specific involvement of the dorsolateral bed nucleus of the stria terminalis (dl BST) in the formalin-induced pain response in rats. The present study investigated pain effects on mice behaviors. Because the dl BST is densely populated with corticotropin-releasing hormone (CRH) neurons, we examined sex differences in these parameters for the dl BST CRH neurons in male and female mice of a mouse line for which the CRH gene promoter (corticotropin-releasing factor [CRF]-Venus ΔNeo) controls the expression of the modified yellow fluorescent protein (Venus). Approximately 92% of Venus-positive cells in the dl BST were also CRH mRNA-positive, irrespective of sex. Therefore, the cells identified using Venus fluorescence were regarded as CRH neurons. A female-biased sex difference was observed in pain-induced behaviors during the interphase (5–15 min after formalin injection) but not during the later phase (phase 2, 15–60 min) in wild-type mice. In CRF-Venus ΔNeo mice, a female-biased difference was observed in either the earlier phase (phase 1, 0–5 min) or the interphase, but not in phase 2. Patch-clamp recordings taken using an acute BST slice obtained from a CRF-Venus ΔNeo mouse after formalin injection showed miniature excitatory postsynaptic currents (mEPSCs) and miniature inhibitory postsynaptic currents (mIPSCs). Remarkably, the mEPSCs frequency was higher in the Venus-expressing cells of formalin-injected female mice than in vehicle-treated female mice. Male mice showed no increase in mEPSC frequency by formalin injection. Formalin injection had no effect on mEPSC or mIPSC amplitudes in either sex. Pain-induced changes in mEPSC frequency in putative CRH neurons were phase-dependent. Results show that excitatory synaptic inputs to BST CRH neurons are temporally enhanced along with behavioral sex differences in pain response, suggesting that pain signals alter the BST CRH neurons excitability in a sex-dependent manner. [ABSTRACT FROM AUTHOR]

Abstract: Binge-like ethanol treatment of septal neurons blunts GABAAR-mediated miniature postsynaptic currents (mPSCs), suggesting it arrests synaptic development. Ethanol may disrupt postsynaptic maturation by blunting feedback signaling through immature GABAARs. Here, the impact of ethanol on the sensitivity of mPSCs to zolpidem, zinc and 3α-hydroxy-5α-pregnan-20-one (3α-OH-DHP) was tested. The decay phase of mPSCs showed concentration-dependent potentiation by zolpidem (0.03–100 μM), which was substantially blunted after ethanol exposure. Since zolpidem potentiation exhibited a substantial age-dependent increase in untreated neurons, this finding supported the idea that ethanol arrests synaptic development. GABAAR α1 subunit protein also increased with age in untreated neurons, paralleling enhanced sensitivity to zolpidem. Surprisingly, α1 levels were not reduced by binge ethanol even though mPSCs were relatively zolpidem-insensitive. Zinc (3–30 μM) decreased mPSC parameters in a concentration- and age-related manner with older untreated cells showing less inhibition. However, there was no increase in mPSC zinc sensitivity after binge ethanol as would be expected if a general arrest of synaptic maturation had occurred. 3α-OH-DHP (3–1000 nM) induced concentration-dependent potentiation of mPSC decay. Although potentiation was age-independent, binge ethanol treatment exaggerated sensitivity to this neurosteroid. Finally, chronic picrotoxin pretreatment (100 μM) intended to mimic GABAAR inhibition from ethanol pretreatment did not significantly change mPSC modulation by zolpidem, zinc or 3α-OH-DHP. These results suggest that binge ethanol treatment selectively arrests a subset of processes important for maturation of postsynaptic GABAA Rs. However, it is unlikely that ethanol causes a broad arrest of postsynaptic development through a direct inhibition of GABAAR signaling. [Copyright &y& Elsevier]