title: Chronic peripheral administration of serotonin inhibits thyroid function in the rat.
abstract: We studied the effect of chronic intraperitoneal (ip) administration of serotonin (5-HT) and thyroid function. We injected daily intraperitoneally for 10 days different doses of 5-HT, and measured plasma thyroid hormones and TSH levels. There was a decrease in the plasma levels of T3 and T4 with medium doses of 5-HT (0.2 and 0.4 mg/Kg bw for T3, and 0.2 for T4). No effects were evidenced on the plasma levels of TSH. In normal environmental conditions, the site action of 5-HT outside the blood-brain barrier is active when the 5-HT is injected at defined doses. This is probably a result of down-regulation independent of the hypothalamus-pituitary-thyroid axis.
authors.affiliation: Second University of Naples, Faculty of Medicine and Surgery, Department of Experimental Medicine, Human Physiology Section, Napoli, Italy (GB, AS).
authors.forename: Alessio
authors.initials: A
authors.lastname: Sullo
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Brizzi
authors.forename: Nicola
authors.initials: N
authors.lastname: Maffulli
keywords: brown adipose tissue; deiodinase activity; rat organs; serotonin; thermogenesis; thyroid hormone