title: Effects of thyroid state on serotonin, 5-hydroxyindoleacetic acid and substance P contents in discrete brain nuclei of adult rats.
abstract: The effects of chemical thyroidectomy produced by propylthiouracil treatment or hyperthyroidism produced by daily injections of thyroxine on the content of serotonin, its metabolite 5-hydroxyindoleacetic acid and of substance P in discrete brain nuclei of adult rats have been studied. Brain nuclei were removed by punches of frozen brain slices. The serotonin and 5-hydroxyindoleacetic acid contents were measured by high performance liquid chromatography with electrochemical detection while substance P was assayed by radioimmunoassay. The serotonin level was significantly increased in 11 nuclei of the hypothyroid and in 12 nuclei of the hyperthyroid rats. The 5-hydroxyindoleacetic acid levels were higher in 16 nuclei of the hypothyroid and 7 nuclei of the hyperthyroid animals. The state of the thyroid gland in adult rats also affected the substance P system but less consistently than the serotonin pathway. Thus, the substance P content in the brain of propylthiouracil-treated animals increased significantly in 4 nuclei while it decreased in the septum lateralis and the striae terminalis. Following the chronic thyroxine injections, the substance P level was increased in the nucleus caudatus putamen and the tractus diagonalis and was decreased in the area ventralis tegmenti. We previously reported that neonatal thyroidectomy caused a general increase of the substance P and serotonin contents in many brain nuclei of young rats. It appears that the effects of chemical thyroidectomy on mature and immature rat brain are different for the substance P system, suggesting that thyroxine plays an important role in the maturation of substance P-containing neurons.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism*; D008297:Male; D009434:Neural Pathways / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*; D013963:Thyroid Hormones / Q000502:physiology*; D013974:Thyroxine / Q000502:physiology
chemical_list: D013963:Thyroid Hormones; D012701:Serotonin; D013373:Substance P; D006897:Hydroxyindoleacetic Acid; D013974:Thyroxine