title: GABAergic control of the activity of the central nucleus of the amygdala in low- and high-anxiety rats.
abstract: The aim of this study was to examine the role of GABAergic neurotransmission in amygdala nuclei in low- (LR) and high-anxiety (HR) rats after repeated corticosterone administration and acute injection of the benzodiazepine midazolam. The animals were divided into LR and HR groups based on the duration of their conditioned freezing in a contextual fear test (CFT). Repeated daily administration of corticosterone (20 mg/kg s.c.) for 21 injections increased anxiety-like behavior in the open field and reduced body weight in both the LR and HR groups. These effects of corticosterone administration were more pronounced in the HR group. Moreover, in the HR group, chronic corticosterone administration increased the duration of freezing in the CFT test compared with the appropriate control group and treated LR rats. The behavioral effects in HR rats were accompanied by an increase in the expression of c-Fos in the lateral (LA) and central (CeA) nuclei of the amygdala and by a decrease in GABA-A alpha-2 subunit density in the CeA. Acute midazolam administration significantly attenuated the neophobia and conditioned fear responses, decreased c-Fos expression in the LA and CeA, and increased alpha-2 subunit density in the CeA only in the HR group. These studies have shown that HR rats are more susceptible to the anxiogenic effects of chronic corticosterone administration, which are associated with the attenuation of GABAergic control over the amygdala output that controls emotional responses. The current data may increase understanding of the neurobiological mechanisms responsible for individual differences in the psychopathological processes induced by repeated administration of high doses of glucocorticoids or by elevated levels of these hormones, which are associated with chronic stress and affective pathology.
authors: Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland. Electronic address: skorzews@ipin.edu.pl.
authors: Anna
authors: A
authors: Skórzewska
authors: Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland.
authors: Małgorzata
authors: M
authors: Lehner
authors: Department of Experimental and Clinical Pharmacology, Medical University, 1B Banacha Street, 02-097 Warsaw, Poland.
authors: Aleksandra
authors: A
authors: Wisłowska-Stanek
authors: Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland.
authors: Danuta
authors: D
authors: Turzyńska
authors: Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland.
authors: Alicja
authors: A
authors: Sobolewska
authors: Department of Experimental and Clinical Pharmacology, Medical University, 1B Banacha Street, 02-097 Warsaw, Poland.
authors: Paweł
authors: P
authors: Krząścik
authors: Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland; Department of Experimental and Clinical Pharmacology, Medical University, 1B Banacha Street, 02-097 Warsaw, Poland.
authors: Adam
authors: A
authors: Płaźnik
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D001008:Anxiety Disorders / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D066272:Basolateral Nuclear Complex / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D066274:Central Amygdaloid Nucleus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D003345:Corticosterone; D004195:Disease Models, Animal; D005239:Fear / Q000187:drug effects / Q000502:physiology; D046352:Freezing Reaction, Cataleptic / Q000187:drug effects / Q000502:physiology; D018757:GABA Modulators / Q000494:pharmacology; D007206:Individuality; D008297:Male; D008874:Midazolam / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D014151:Anti-Anxiety Agents; D018757:GABA Modulators; C520011:Gabra2 protein, rat; D016760:Proto-Oncogene Proteins c-fos; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D008874:Midazolam; D003345:Corticosterone
keywords: Amygdala; Anxiety; Chronic corticosterone; GABA-A receptor alpha-2 subunits; Individual differences; Midazolam; c-Fos