title: Interaction of melatonin and gonadotropin-inhibitory hormone on the zebrafish brain-pituitary-reproductive axis.
abstract: Circadian cycles and photoperiod are known to influence reproductive physiology in several animals. Neuropeptides, such as gonadotropin-inhibitory hormone (GNIH) and gonadotropin-releasing hormone (GNRH), are influenced by melatonin in birds and mammals. The present study demonstrates the role of melatonin in oocyte maturation in the zebrafish (Danio rerio), via the brain-pituitary-reproductive axis, under different photic conditions. Melatonin was significantly higher both in the whole brain and ovary under continuous dark (DD) compared to continuous light (LL) conditions. Transcription of gnih in the brain was high in LL, but low in DD; similarly, melatonin exogenous treatment reduced gnih in cultured brain in a dose-dependent manner. Expression of gnrh3, however, was high in both continuous photic conditions (DD and LL), whereas fshb and lhb were high only during DD. kiss2, another neuropeptide, was high in LL, but kiss1 remain unchanged among the conditions. At the gonad level, expression of fshr, lhcgr, mtnr1aa, and mtnr1ab tracked with the expression of their respective ligand in DD and LL. The expression of mprb is high in DD ovary, although intra-ovarian growth factors (tgfb1a and bmp15) were low. The measured increased percentages of germinal vesicle breakdown, expression of Cyclin B1, and reduced Cdc2p34 phosphorylation are consistent with increased maturation in the dark. Our study thus links melatonin to the inhibition of gnih in the brain-pituitary-reproductive axis of zebrafish in response to photic conditions.
authors.affiliation: Biological Rhythm Laboratory, Animal Resources Programme, Institute of Bioresources and Sustainable Development, Government of India, Imphal, Manipur, India.
authors.forename: Thangal
authors.initials: T
authors.lastname: Yumnamcha
authors.affiliation: Biological Rhythm Laboratory, Animal Resources Programme, Institute of Bioresources and Sustainable Development, Government of India, Imphal, Manipur, India.
authors.forename: Zeeshan A
authors.initials: ZA
authors.lastname: Khan
authors.affiliation: Biological Rhythm Laboratory, Animal Resources Programme, Institute of Bioresources and Sustainable Development, Government of India, Imphal, Manipur, India.
authors.forename: Chongtham
authors.initials: C
authors.lastname: Rajiv
authors.affiliation: Biological Rhythm Laboratory, Animal Resources Programme, Institute of Bioresources and Sustainable Development, Government of India, Imphal, Manipur, India.
authors.forename: Sijagurumayum D
authors.initials: SD
authors.lastname: Devi
authors.affiliation: Biological Rhythm Laboratory, Animal Resources Programme, Institute of Bioresources and Sustainable Development, Government of India, Imphal, Manipur, India.
authors.forename: Gopinath
authors.initials: G
authors.lastname: Mondal
authors.affiliation: Biological Rhythm Laboratory, Animal Resources Programme, Institute of Bioresources and Sustainable Development, Government of India, Imphal, Manipur, India.
authors.forename: Haobijam
authors.initials: H
authors.lastname: Sanjita Devi
authors.affiliation: Department of Biotechnology, Gauhati University, Guwahati, Assam, India.
authors.forename: Rupjyoti
authors.initials: R
authors.lastname: Bharali
authors.affiliation: Biological Rhythm Laboratory, Animal Resources Programme, Institute of Bioresources and Sustainable Development, Government of India, Imphal, Manipur, India.
authors.forename: Asamanja
authors.identifier: 0000-0002-8656-7459
authors.initials: A
authors.lastname: Chattoraj
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D008027:Light; D008297:Male; D008550:Melatonin / Q000235:genetics / Q000378:metabolism*; D010053:Ovary / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D029961:Zebrafish Proteins; D008550:Melatonin
keywords: GVBD; gnrh; kiss; photoperiod; reproduction