EFFECTS OF ADRENALECTOMY AND CORTICOSTERONE REPLACEMENT ON DIURNAL [H-3] CITALOPRAM BINDING IN RAT MIDBRAIN

Corticosteroids modulate the expression and/or functions of several se rotonin (5-hydroxytryptamine; 5-HT) receptors. Conversely, analyses of the effects of corticosteroids upon 5-HT reuptake systems have been s carce and contradictory. Herein, the diurnal rhythm of. midbrain [H-3] citalopram binding to 5-HT transporters was analysed in sham and 11 da y adrenalectomised rats. In addition, adrenalectomised rats were eithe r complemented or not with corticosterone pellets (12.5-200 mg). Analy ses of body weight increases and plasma adrenocorticotropic and cortic osterone levels indicated that the protocol allowed the stimulation of mineralocorticoid receptors (MRs; 12.5 mg pellets) or the stimulation of both MRs and glucocorticoid receptors (GRs; 50-200 mg pellets). Ho wever, besides the observation of a slight, but significant diurnal (c orticosteroid-independent) rhythm in 5-HT transporter binding (morning > evening), it was found that neither adrenalectomy nor corticosteroi d receptor stimulation affected midbrain [H-3]citalopram binding. (C) 1997 Elsevier Science Ireland Ltd.