title: Enhanced GABAergic transmission in the central nucleus of the amygdala of genetically selected Marchigian Sardinian rats: alcohol and CRF effects.
abstract: The GABAergic system in the central amygdala (CeA) plays a major role in ethanol dependence and the anxiogenic-like response to ethanol withdrawal. Alcohol dependence is associated with increased corticotropin releasing factor (CRF) influence on CeA GABA release and CRF type 1 receptor (CRF(1)) antagonists prevent the excessive alcohol consumption associated with dependence. Genetically selected Marchigian Sardinian (msP) rats have an overactive extrahypothalamic CRF(1) system, are highly sensitive to stress, and display an innate preference for alcohol. The present study examined differences in CeA GABAergic transmission and the effects of ethanol, CRF and a CRF(1) antagonist in msP, Sprague Dawley, and Wistar rats using an electrophysiological approach. We found no significant differences in membrane properties or mean amplitude of evoked GABA(A)-inhibitory postsynaptic potentials (IPSPs). However, paired-pulse facilitation (PPF) ratios of evoked IPSPs were significantly lower and spontaneous miniature inhibitory postsynaptic current (mIPSC) frequencies were higher in msP rats, suggesting increased CeA GABA release in msP as compared to Sprague Dawley and Wistar rats. The sensitivity of spontaneous GABAergic transmission to ethanol (44 mM), CRF (200 nM) and CRF(1) antagonist (R121919, 1 μM) was comparable in msP, Sprague Dawley, and Wistar rats. However, a history of ethanol drinking significantly increased the baseline mIPSC frequency and decreased the effects of a CRF(1) antagonist in msP rats, suggesting increased GABA release and decreased CRF(1) sensitivity. These results provide electrophysiological evidence that msP rats display distinct CeA GABAergic activity as compared to Sprague Dawley and Wistar rats. The elevated GABAergic transmission observed in naïve msP rats is consistent with the neuroadaptations reported in Sprague Dawley rats after the development of ethanol dependence.
authors.affiliation: Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, SP30-1150, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Herman
authors.forename: Marsida
authors.initials: M
authors.lastname: Kallupi
authors.forename: George
authors.initials: G
authors.lastname: Luu
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Oleata
authors.forename: Markus
authors.initials: M
authors.lastname: Heilig
authors.forename: George F
authors.initials: GF
authors.lastname: Koob
authors.forename: Roberto
authors.initials: R
authors.lastname: Ciccocioppo
authors.forename: Marisa
authors.initials: M
authors.lastname: Roberto
mesh_terms: D000437:Alcoholism / Q000235:genetics / Q000503:physiopathology*; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000502:physiology*; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D059330:GABAergic Neurons / Q000187:drug effects / Q000502:physiology*; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000502:physiology; D013045:Species Specificity; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
chemical_list: D011963:Receptors, GABA-A; D000431:Ethanol; D003346:Corticotropin-Releasing Hormone