The proposed line of investigation is principally designed to study in rats the role of serotonin neurons in the control of specific brain functions; i.e., sleep, nociception, and growth hormone and prolactin secretion. The effects on these functions of amino acid, drug, and diet induced alterations in serotonin transmission will be explored. Other studies will determine if agents suspected of making serotonin receptors supersensitive cause the above brain outputs to repons to smaller-than-normal doses of tryptophan, serotonin agonists, or serotonin reuptake blockers. In addition, a portion of the proposed studies will attempt to determine if peripheral and/or central nervous system mechanisms are responsible for caffeine- and morphine-induced increments in brain tryptophan and serotonin. Finally, in associated experiments, we will also study the effects of administering methyldopa, a large neutral amino acid drug, on sleep and prolactin secretion, and of tyrosine, which in certain cases stimulates catecholamine synthesis, on sleep and pain sensitivity. The information derived from these nutritional, pharmacologic, and psychopharmacologic investigations should provide new insights into the involvement of central nervous system serotonin (and catecholamine) neurons in the control of sleep, pain perception, and pituitary hormone secretion.
