Immunohistochemical localization of cocaine‐ and amphetamine‐regulated transcript peptide (CARTp) in the brain of the pigeon (Columba livia) and zebra finch (Taeniopygia guttata)

Abstract

Cocaine- and amphetamine-regulated transcript peptides (CARTp) are neuropeptides that act as neurotransmitters in the brain of vertebrates. The expression of CARTp has been characterized in teleosts, amphibians, and several mammalian species, but comparative data in reptiles and birds are nonexistent. In this study, we show the distribution of immunoreactivity against CART peptides (CARTp-ir) in the brains of two bird species: the pigeon (Columba livia) and zebra finch (Taeniopygia guttata). We found CARTp-ir cells and terminals in the brains of both, but no major differences between the two species. As in mammals, teleost fish, and amphibians, CARTp-ir terminals and cells were abundant in subpallial regions, particularly the striatum and nucleus accumbens. We also found CARTp-ir cells and terminals in the hypothalamus, and a large number of CARTp-ir terminals in the substantia nigra, ventral tegmental area, periaqueductal gray, parabrachial nucleus, and dorsal vagal complex. However, in contrast to other vertebrates, CARTp-ir was not found in the olfactory bulb. In addition there was almost no CARTp-ir in the pallium or the hippocampal formation, and little CARTp-ir in the cerebellum. The conserved expression of CARTp in the subpallium, hypothalamus, and dorsal vagal complex of birds suggests that some of the functions of CARTp, such as regulation of food intake and interactions with the social control network and mesolimbic reward system, are conserved among vertebrates. J. Comp. Neurol. 524:3747-3773, 2016. © 2016 Wiley Periodicals, Inc.

Concurrent changes in photoperiod-induced seasonal phenotypes and hypothalamic CART peptide-containing systems in night-migratory redheaded buntings

“…Hypothalamic CART-immunoreactivity of buntings was comparable to that found in other birds (Singh et al 2016a ; Gutierrez-Ibanez et al 2016 ). So, based on other bird study, we can speculate CART playing a significant physiological roles in redheaded buntings.…”

“…Interestingly, we also found CART-immunoreactive in SCN of buntings, similar to that in pigeons (Gutierrez-Ibanez et al 2016 ) but not zebra finches (Singh et al 2016a ; Gutierrez-Ibanez et al 2016 ). Taken together, the CART-immunoreactive in SCNm and SCNv, which constitute avian SCN (Yoshimura et al 2001 ; Rastogi et al 2013 ), suggests the involvement of CART in the circadian clock-dependent phtotoperiodic responses in buntings.…”

“…CART inhibits TRH-induced prolactin secretion but not the TRH-induced TSH secretion (Raptis et al 2004 ). We also found CART-immunoreactivity cells in SOv of redheaded buntings, similar to zebra finches (Singh et al 2016a ) but unlike in pigeons (Gutierrez-Ibanez et al 2016 ). We speculate CART SOv neurons play a role in the neuroendocrine regulation and/ or modulation of hypothalamic nonapeptides in redheaded buntings, as in rats in which CART was found co-expressed with oxytocin- and vasopressin-containing neurons in the supraoptic nucleus of rat (Vrang et al 1999 ; Elias et al 2001 ), with dense CART-immunoreactivity terminals in the neurohypophysis (Koylu et al 1997 ).…”

“…We observed that the POA in buntings was organized into PONa, PONm, and PPN, and CART-immunoreactive cells seen in the PONa and PONm, not in PPN. Distinct CART-immunoreactivity was also observed in the POA of zebra finches (Singh et al 2016a ) and piegons (Gutierrez-Ibanez et al 2016 ). Both, the CART-immunoreactive cell number and percent fluorescent area in PONm, not PONa, showed distinct changes with photoperiod-induced seasonal states in redheaded buntings.…”

“…This is intriguing since CART peptide seems highly conserved both in the distribution and function in the brain (Lázár et al 2004 ; Calle et al 2006 ; Singru et al 2007 ; Subhedar et al 2011 ; Akash et al 2014 ; Singh et al 2016a ). The organization and functional significance of CART have been described in the brain of several non-mammalian vertebrates including teleosts [catfish, Clarias batrachus : (Singru et al 2007 ); Clarias gariepinus : (Subhedar et al 2011 ), and zebrafish, Danio rerio (Akash et al 2014 )], frogs [ Rana esculenta : (Lázár et al 2004 ); Xenopus laevis : (Calle et al 2006 )], and birds [zebra finch, Taeniopygia guttata (Singh et al 2016a ; Gutierrez-Ibanez et al 2016 ) and pigeon, Columba livia (Gutierrez-Ibanez et al 2016 )]. In addition to energy balance, CART also plays a role in the reproductive regulation (True et al 2013 ).…”