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

Louise Thomas, C C Purvis, Janice Drew, David Abramovich, Lynda Williams

Research output: Contribution to journalArticlepeer-review

80 Citations (Scopus)


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-[I-125] 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 trochlea nuclei, the motor and sensory trigeminal nuclei, the facial nuclei, and the cochlea nuclei. The localization of MT1 receptor subtype gene expression as determined by in situ hybridization matched the localization of 2-[I-125] 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-[I-125] 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.

Original languageEnglish
Pages (from-to)218-224
Number of pages7
JournalJournal of Pineal Research
Issue number4
Early online date17 Oct 2002
Publication statusPublished - Nov 2002


  • circadian rhythms
  • human fetus
  • melatonin
  • receptor subtypes
  • sleep-wake cycle
  • hamsters phodopus-sungorus
  • 2-<I-125> iodomelatonin binding
  • prolactin secretion
  • circadian-rhythms
  • core temperature
  • biological clock
  • primate infants
  • photoperiod
  • sites

Cite this