Concurrent changes in photoperiod-induced seasonal phenotypes and hypothalamic CART peptide-containing systems in night-
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ORIGINAL ARTICLE
Concurrent changes in photoperiod‑induced seasonal phenotypes and hypothalamic CART peptide‑containing systems in night‑migratory redheaded buntings Omprakash Singh1,2 · Neha Agarwal3,4 · Anupama Yadav3 · Sumela Basu1,2 · Shalie Malik3 · Sangeeta Rani3 · Vinod Kumar4 · Praful S. Singru1,2 Received: 10 March 2020 / Accepted: 4 October 2020 / Published online: 3 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This study tested the hypothesis whether hypothalamic cocaine-and amphetamine-regulated transcript (CART)-containing systems were involved in photoperiod-induced responses associated with spring migration (hyperphagia and weight gain) and reproduction (gonadal maturation) in migratory songbirds. We specifically chose CART to examine neural mechanism(s) underlying photoperiod-induced responses, since it is a potent anorectic neuropeptide and involved in the regulation of changes in the body mass and reproduction in mammals. We first studied the distribution of CART-immunoreactivity in the hypothalamus of migratory redheaded buntings (Emberiza bruniceps). CART-immunoreactive neurons were found extensively distributed in the preoptic, lateral hypothalamic (LHN), anterior hypothalamic (AN), suprachiasmatic (SCN), paraventricular (PVN), dorsomedialis hypothalami (DMN), inferior hypothalamic (IH), and infundibular (IN) nuclei. Then, we correlated hypothalamic CART-immunoreactivity in buntings with photostimulated seasonal states, particularly winter non-migratory/non-breeding (NMB) state under short days, and spring premigratory/pre-breeding (PMB) and migratory/ breeding (MB) states under long days. There were significantly increased CART-immunoreactive cells, and percent fluorescent area of CART-immunoreactivity was significantly increased in all mapped hypothalamic areas, except the SCN, PVN, AN, and DMN in photostimulated PMB and MB states, as compared to the non-stimulated NMB state. In particular, CART was richly expressed in the medial preoptic nucleus, LHN, IH and IN during MB state in which buntings showed reduced food intake and increased night-time activity. These results suggest that changes in the activity of the CART-containing system in different brain regions were associated with heightened energy needs of the photoperiod-induced seasonal responses during spring migration and reproduction in migratory songbirds. Keywords Cocaine- and amphetamine-regulated transcript · E. bruniceps · Energy balance · Hypothalamus · Migration Omprakash Singh and Neha Agarwal contributed equally to the work. * Vinod Kumar [email protected] * Praful S. Singru [email protected] 1
School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Jatni, Khurda 752050, Odisha, India
2
Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
3
Department of Zoology, University of Lucknow, Lucknow 226007, India
4
Department of Zoology, University of Delhi, Delhi 110007, India
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