Serotonin receptor subtype gene expression in the hippocampus of aged ratsfollowing chronic amitriptyline treatment

The raphe-hippocampal 5-HT system plays a key role in the modulation of moo d, memory and neuroendocrine responses. In the elderly, there is an increas ed incidence of disturbances of these functions. We examined the effects of ageing and of chronic antidepressant treatment upon 5-HT receptor subtype mRNA expression in the hippocampus and raphe of cognitively tested rats. Am itriptyline treatment decreased 5-HT1A receptor mRNA expression in the dors al raphe nucleus of the aged rats (24% fall compared to saline treated cont rols, p < 0.01) but not in the young rats. Neither age nor amitriptyline (1 0 mg/kg, i.p.) administration for 10 weeks altered 5-HT1A, 5-HT2A, 5-HT2C o r 5-HT7 receptor mRNA expression in any hippocampal subregion. This suggest s a difference in responsiveness to amitriptyline with ageing originating a t the level of the raphe 5-HT1A autoreceptor gene expression. (C) 1999 Else vier Science B.V. All rights reserved.