RT Journal Article SR Electronic T1 Corticosteroids Alter 5-Hydroxytryptamine1AReceptor-effector Pathway in Hippocampal Subfield CA3 Pyramidal Cells JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 1227 OP 1233 VO 284 IS 3 A1 Dayne Y. Okuhara A1 Sheryl G. Beck YR 1998 UL http://jpet.aspetjournals.org/content/284/3/1227.abstract AB Corticosteroids influence neuron activity in the hippocampus through the activation of mineralocorticoid and glucocorticoid receptors. For example, corticosteroids modulate the responses elicited by the activation of several different neurotransmitter receptors on hippocampal pyramidal cells. However, the effects of corticosteroids on the serotonin (5-HT) receptors systems in subfield CA3 are not completely known. Therefore, we used single-electrode voltage clamp techniques to examine the actions of chronic corticosteroid treatment on the 5-HT1A receptor-effector pathway in rat hippocampal subfield CA3 pyramidal cells. Activation of the 5-HT1Areceptor increases the conductance of an inward rectifying potassium channel, increasing outward current. The treatment groups used in this investigation were: adrenalectomy, selective mineralcorticoid receptor activation with aldosterone, mineralcorticoid receptor and glucocorticoid receptor activation with high levels of corticosterone and SHAM. Corticosteroids altered the characteristics of the 5-HT concentration-response curve for the 5-HT1A receptor. The effective concentration at 50% of maximum value was smaller in cells from the adrenalectomy treatment group compared to the other treatment groups. The maximum response was smaller in cells from the high corticosterone treatment group compared to SHAM and adrenalectomy treatment group animals. G protein function was also altered by corticosterone treatment. Less current was elicited by guanosine 5′-0-13-thiotriphosphate in cells from the high corticosterone treatment group compared to the other treatment groups and in cells from the SHAM treatment group compared to adrenalectomy treatment group animals. Corticosteroid treatment did not alter the current-voltage relationship, the conductance or the reversal potential of the potassium current linked to the 5-HT1Areceptor. We conclude that corticosteroids alter the 5-HT1Areceptor-mediated-response in hippocampal subfield CA3 neurons at site(s) downstream of the receptor. The American Society for Pharmacology and Experimental Therapeutics