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Pineal melatonin concentrations during day and night in the adult hedgehog: Effect of a light pulse at night and superior cervical ganglionectomy
Author(s) -
Saboureau Michel,
VivienRoels Berthe,
Pevet Paul
Publication year - 1991
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1991.tb00462.x
Subject(s) - ganglionectomy , melatonin , pineal gland , photoperiodism , darkness , medicine , endocrinology , circadian rhythm , biology , pinealocyte , hedgehog , botany , alternative medicine , pathology , biochemistry , gene
The European hedgehog ( Erinaceus europaeus L.) is a hibernating mammal and seasonal breeder in which numerous circadian and circannual rhythms are entrained and synchronized by photoperiod. The present study was undertaken in order to establish the involvement of the pineal gland in transducing the photoperiodic message in this species. Pineal melatonin concentrations were determined by radioimmunoassay in female hedgehogs kept under natural climatic conditions and killed during the light:dark (L:D) cycle in spring and autumn, after the interruption of darkness by a 45 min light pulse, and after bilateral superior cervical ganglionectomy (SCGx). Absolute melatonin concentrations were low (< 100 pg/pineal) in the pineal gland. Under natural climatic conditions, in spring and in autumn, pineal melatonin concentrations exhibited a marked diurnal rhythmicity, with very low levels in the day (1200: < 10 pg/pineal) and high levels during the night (2200: 71.9 ± 18.6 pg/pineal; 0200: 42.5 ± 15.6 pg/pineal). The 45 min light pulse during darkness depressed rapidly and significantly the melatonin content (dark + light [D + L]: < 10 pg/pineal), but a subsequent return to darkness restored high melatonin content after approximately 2 h (D + L + D: 65.4 ± 20.2 pg/pineal). After bilateral SCGx, melatonin concentrations were reduced and no increase during night could be observed, either in animals sacrificed 42 days after SCGx or in animals killed 2 years after SCGx. In the hedgehog, as in other mammals, pineal melatonin concentrations are related to the light:dark cycle. Such data indicate that during the year, in this species, the effects of light on seasonal endocrine rhythms may be mediated by the pineal gland.