THE NEUROENDOCRINOLOGICAL PROFILE OF ROXINDOLE, A DOPAMINE AUTORECEPTOR AGONIST, IN SCHIZOPHRENIC-PATIENTS

Roxindole is a potent autoreceptor-selective dopamine agonist with add itional properties as a serotonin reuptake inhibitor and 5-HT1A agonis t. In order to get more insight into its mode of action in various psy chiatric populations, we evaluated the effects of subchronic roxindole treatment on pituitary and adrenal hormone secretion, i.e. release of prolactin, thyroid stimulating hormone (TSH), growth hormone (GH), lu teinizing hormone (LH), and cortisol. Fifteen schizophrenic patients w ith positive and negative symptomatology, respectively, were treated w ith roxindole for 28 days. Both basal and thyrotropin releasing hormon e (TRH) -induced prolactin secretion diminished significantly to 26.4% and 22.8% of baseline levels, respectively, under roxindole. Basal GH secretion was insignificantly elevated by 89%, whereas GH levels incr eased nearly 3-fold after stimulation by TRH. TSH levels decreased ins ignificantly to 57.5% of baseline levels, while TRH-induced TSH releas e was not affected by subchronic roxindole. Roxindole treatment influe nced neither LH secretion nor cortisol release. Our results indicate t hat roxindole's dopaminergic actions might prevail over its serotonerg ic effects, at least as far as the regulation of anterior pituitary ho rmone secretion is concerned.