Melatonin receptors in human fetal brain: 2-[125I]iodomelatonin binding and MT1 gene expression

• Published in: Journal of pineal research Vol. 33; no. 4; pp. 218 - 224
• Main Authors: Thomas, Louise, Purvis, Cheryl C., Drew, Janice E., Abramovich, David R., Williams, Lynda M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Munksgaard International Publishers 01-11-2002; Blackwell
• Subjects: Biological and medical sciences; Brain - embryology; Brain - metabolism; Brain Stem - embryology; Brain Stem - metabolism; Cell receptors; Cell structures and functions; circadian rhythms; Fetus - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Hormone receptors. Growth factor receptors. Cytokine receptors. Prostaglandin receptors; human fetus; Humans; Hypothalamus - embryology; Hypothalamus - metabolism; Iodine Radioisotopes; melatonin; Melatonin - analogs & derivatives; Melatonin - metabolism; Molecular and cellular biology; receptor subtypes; Receptors, Cell Surface - metabolism; Receptors, Cytoplasmic and Nuclear - metabolism; Receptors, Melatonin; Thalamus - embryology; Thalamus - metabolism; Human; Fetal development; Central nervous system; Fetus; Biological rhythm; Circadian rhythm; Gene expression; MT1 melatonin receptor; Site of action; Biological receptor; Hormonal receptor; Brain (vertebrata)
• ISSN: 0742-3098; 1600-079X
• DOI: 10.1034/j.1600-079X.2002.02921.x

: The purpose of this study was to identify sites of action of melatonin in the human fetal brain by in vitro autoradiography and in situ hybridization. Specific, guanosine triphosphate (GTP) sensitive, binding of 2‐[125I]iodomelatonin was localized to the leptomeninges, cerebellum, thalamus, hypothalamus, and brainstem. In the hypothalalmus, specific binding was present in the suprachiasmatic nuclei (SCN) as well as the arcuate, ventromedial and mammillary nuclei. In the brainstem specific binding was present in the cranial nerve nuclei including the oculomotor nuclei, the trochlear nuclei, the motor and sensory trigeminal nuclei, the facial nuclei, and the cochlear nuclei. The localization of MT1 receptor subtype gene expression as determined by in situ hybridization matched the localization of 2‐[125I]iodomelatonin binding. No MT2 receptor subtype gene expression was detected using this technique. Thus, melatonin may act on the human fetus via the MT1 receptor subtype at a number of discrete brain sites. A major site of action of melatonin in both fetal and adult mammals is the pars tuberalis of the pituitary gland. However, no 2‐[125I]iodomelatonin binding or melatonin receptor gene expression was detected in the pituitary gland in the present study, indicating that the pituitary, particularly the pars tuberalis, is not a site of action of melatonin in the human fetus.