Abstract
The thyrotropin-releasing hormone (TRH) content in whole hypothalamus was measured by specific radioimmunoassay in rats exposed to a daily light-dark cycle (06:00–18:00 light, 18:00–06:00 dark) and in animals exposed to constant light or constant darkness for 12 days. A nyctohemeral variation of hypothalamic TRH was observed in light-dark exposed animals, while this variation was abolished by exposure either to constant light or constant darkness. These data indicate that any study involving hypothalamic TRH determination should be carried out taking into account the diurnal variation and the effect of environmental light exposure.
Similar content being viewed by others
References
Collu R., Du Ruisseau P., Taché Y., Ducharme J.R. Thyrotropin-releasing hormone in rat brain: nyctohe- meral variations. Endocrinology 100: 1391, 1977.
Mannisto P.T., Pakkanen J., Ranta T., Koivusalo F., Leppaluoto J. Diurnal variations of medial basal and anterior hypothalamic thyroliberin (TRH) and serum thyrotropin (TSH) concentrations in male rats. Life Sci. 23: 1343, 1978.
Koivusalo F., Leppaluoto J. Brain TRF immunoreactivity during various physiological and stress conditions in the rat. Neuroendocrinology 29: 231, 1979.
Kerdelhue B., Palkovits M., Karteski M., Reinberg A. Orcadian variations in substance P, Lulberin (LH-RH) and thyroliberin (TRH) contents in hypothalamic and extrahypothalamic brain nuclei of adult male rats. Brain Res. 206: 405, 1981.
Brammer G.L., Morley J.E., Geller E., Yuwiler A., Hershman J.H. Hypothalamus-pituitary-thyroid axis interactions with pineal gland in the rat. Am. J. Physiol. 236: E 416, 1979.
Martino E., Lernmark A., Seo H., Steiner D.F., Refetoff S. High concentration of thyrotropin-releasing hormone in pancreatic islet. Proc. Natl. Acad. Sci. USA 75: 4265, 1978.
Oliver C., Eskay R.L., Ben-Jonathan N., Porter J.C. Distribution and concentration of TRH in rat brain. Endocrinology 95: 540, 1974.
Martino E., Seo H., Refetoff S. Loss of bioreactivity and preservation of immunoreactivity of iodothyrotropin-releasing hormone. Endocrinology 103: 246, 1978.
Berelowitz M., Perlow M.J., Hoffman H.J., Frohman L.A. The diurnal variation of immunoreactive thyrotropin-releasing hormone and somatostatin in the cerebrospinal fluid of rhesus monkey. Endocrinology 109: 2102, 1981.
Jackson I.M.D., Saperstein R., Reichlin S. Thyrotropin-releasing hormone (TRH) in pineal and hypothalamus of the frog: effect of season and illumination. Endocrinology 700: 97, 1977.
Martino E., Seo H., Lernmark A., Refetoff S. Ontogenetic patterns of thyrotropin-releasing hormonelike material in rat hypothalamus, pancreas and retina: selective effect of light deprivation. Proc. Natl. Acad. Sci. USA 77: 4345, 1980.
Schaeffer J.M., Brownstein M.J., Axelrod J. Thyrotropin-releasing hormone-like material in the rat retina: changes due to environmental lighting. Proc. Natl. Acad. Sci. USA 74: 3579, 1977.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Martino, E., Bambini, G., Vaudagna, G. et al. Effects of continuous light and dark exposure on hypothalamic thyrotropin-releasing hormone in rats. J Endocrinol Invest 8, 31–33 (1985). https://doi.org/10.1007/BF03350633
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF03350633