Nicotine-induced brain stimulation reward is modulated by melanocortin-4 receptors in ovariectomized rats

Publication date: Available online 5 February 2020Source: NeuroscienceAuthor(s): Manoj A. Upadhya, Harshita M. Upadhya, Chandrashekhar D. Borkar, Amit G. Choudhary, Uday Singh, Priyanka Chavan, Amul Sakharkar, Praful Singru, Nishikant K. Subhedar, Dadasaheb M. KokareAbstractApart from reproduction, estrogen influences a multitude of processes. Increase in estrogen levels in women is known to promote reward probably mediated via the melanocortin and dopamine systems. Reduced estrogen in post-menopausal women attenuates reward evoking the need for stimulation with greater rewarding salience. This is reflected in the well-recognized phenomena of difficulty in quitting and increased craving for nicotine in women following the onset of menopause. The present study aims at understanding the role of melanocortin receptors (MC-R) in nicotine-induced reward behavior following ovariectomy in rats. The MC4-R mRNA level was increased in ipsilateral nucleus accumbens (Acb) of the intact rats implanted with electrode in medial forebrain bundle and trained in intracranial self-stimulation (ICSS) paradigm. Additional groups of ICSS trained rats were ovariectomized (OVX) and subjected to reward evaluation. Trained OVX rats revealed a significant increase in threshold frequency and rightward shift in rate frequency curve, suggesting reward deficit behavior. However, pre-administration with nicotine, α-MSH or NDP-MSH (MC4-R agonist) to OVX animals restored the rewarding activity in ICSS protoc...
Source: Neuroscience - Category: Neuroscience Source Type: research