[The role of the pineal gland and melatonin in the regulation of adenohypophysial hormone synthesis and secretion].
This paper reviews findings accumulated on the role of the pineal gland and its hormone,melatonin, in the regulation of hypothalamo-adenohypophysial system activity. The effect of melatonin on somatotrophin (GH), thyreotrophin (TSH), and adrenocorticotrophin (ACTH) synthesis and secretion is considered. Results of in vivo and in vitro experiments show that the influence of melatonin on adenohypophysial activity depends on the animal species, age, sex, the concentration of the hormone, and the experimental conditions. Melatonin modifies adenohypophysial hormone synthesis and secretion either directly by influencing the secretory activity of the cells in the anterior pituitary or indirectly by influencing the hypothalamic neurons producing the respective neurohormones which stimulate or inhibit the release of adequate adenohypophysial hormones. Melatonin acts via specific membrane receptors which have been demonstrated in several brain areas, with high concentrations in the hypothalamic suprachiasmatic nucleus and the pars tuberalis of the pituitary. It may also act directly on a genome. Moreover, the response of the hypothalamo-adenohypophysial system to melatonin may depend on this hormone's influence on the metabolism of some neuromediators and/or neuromodulators in the central nervous system.
Juszczak
Marlena
M
Zakład Patofizjologii i Neuroendokrynologii Doświadczalnej, Katedry Patologii Ogólnej i Doświadczalnej, Uniwersytetu Medycznego w Łodzi, Łódź, Poland. marlenaj@bg.umed.lodz.pl
Michalska
Monika
M
D000818:Animals; D006801:Humans; D008550:Melatonin / Q000502:physiology*; D009479:Neuropeptides / Q000502:physiology*; D010908:Pituitary Hormones, Anterior / Q000096:biosynthesis* / Q000378:metabolism*
D009479:Neuropeptides; D010908:Pituitary Hormones, Anterior; C045428:pineal peptide E5; D008550:Melatonin