Reproductive phase related variations in the expression of neuropeptide, cocaine- and amphetamine- regulated transcript (CART) in the brain and pituitary gland of adult male Microhyla ornata.

Cocaine- and amphetamine-regulated transcript (CART) peptide is a multifaceted neuropeptide involved in several physiological functions including appetite and reproduction. While studies in mammals, aves and fishes suggest evolutionary conserved role of CART, the information in amphibian is scanty. We have investigated the reproductive phase related variations of CART in the brain of adult male Microhyla ornata. Seasonal changes in the expression of CART peptide were noticed in the brain and pituitary of M. ornata. Significant differences were observed in the nucleus infundibularis ventralis (NIV), epiphysis (E), anteroventral tegmental region (AV), raphe nucleus (Ra) of the brain and pars intermedia (PI), pars distalis (PD) of the pituitary. Compared to the pre-breeding and post-breeding seasons, increase in CART immunoreactivity was seen in E, NIV, AV, Ra of brain and PI, PD of pituitary gland of animals collected during breeding season. Similarly, highest mRNA levels of CART were also observed in the breeding season in the middle region of brain that includes hypothalamus and pituitary gland. Variation in the levels of CART peptide and mRNA in the brain of M. ornata suggests its conserved role in seasonal control of appetite and reproduction.

Cocaine and amphetamine regulated transcript peptide (CART) in the tadpole brain: Response to different energy states.

Cocaine- and amphetamine-regulated transcript peptide (CART) is an anorexigenic neuropeptide known to play a key role in energy homeostasis across the vertebrate phyla. In the current study, we have investigated the response of the CART immunoreactive system to varying energy states in the brain of a tadpole model. The pro-metamorphic tadpoles of Euphlyctis cyanophlyctis were fasted, or intracranially injected with glucose or 2-deoxy-d-glucose (2DG; an antagonist to glucose inducing glucoprivation) and the response of the CART containing system in various neuroanatomical areas was studied using immunohistochemistry. Glucose administration increased the CART immunoreactivity in the entopeduncular neurons (EN), preoptic area (POA), ventral hypothalamus (vHy) and the Edinger Westphal nucleus (EW) while CART positive cells decrease in response to fasting and glucoprivation. A substantial decrease in CART was noted in the EW nucleus of tadpoles injected with 2DG. These regions might contain the glucose-sensing neurons and regulate food intake in anurans. Therefore, we speculate that the function of central CART and its antagonistic action with NPY in food and feeding circuitry of anurans is evolutionary conserved and might be responsible for glucose homeostasis.

Temperature dependent changes in cocaine- and amphetamine regulated transcript (CART) peptide in the brain of tadpole, Sylvirana temporalis.

Cocaine- and amphetamine-regulated transcript peptide (CARTp) has emerged as a novel neurotransmitter in the brain. Although the physiological role of the peptide has been intensely investigated in mammals, its role in amphibians has not been investigated. In the present study, an attempt has been undertaken to study the expression of CART in the tadpole brain of frog Sylvirana temporalis, subjected to thermal stress. Cells with strong CART-immunoreactivity were observed in the nucleus preoptic area (NPO) of tadpoles exposed to high temperature (37±2°C) as compared to those in the tadpoles exposed to low (12±2°C) and normal (24±2°C) temperatures. In the ventromedial thalamic nucleus (VM) and nucleus posterocentralis thalami (NPC), moderate CART-ir cells were observed in the control groups while number of cells and intensity of immunoreactivity was increased in tadpoles at low and high temperatures. In the nucleus infundibularis ventralis (NIV) and raphe nucleus (RA), CART immunoreactivity increased in the low as well as high temperature treated groups. Intensely stained CART cells were observed in the pituitary of tadpoles exposed to high temperature as compared to low temperature and control groups. We suggest that CART system in the brain and pituitary of tadpole may play a very important role in mediating responses to temperature variations in the environment.