title: Hypothalamic Expression of Melanocortin-4 Receptor and Agouti-related Peptide mRNAs During the Estrous Cycle of Rats.
abstract: Melanocortin- 4 receptor (MC4R) and agouti- related peptide (AgRP) are involved in energy homeostasis in rats. According to MC4R and AgRP effects on luteinizing hormone (LH) secretion, they may influence the estrous cycle of rats. Therefore, the aim of this study was to investigate the expression of MC4R and AgRP mRNAs at different stages of estrous cycle in the rat's hypothalamus. The estrous cycle stages (proestrus, estrus, metestrus and diestrus) were determined in 20 adult female rats using vaginal smears. The rats were divided into four equal groups (n=5). Four ovariectomized rats were selected as controls two weeks after surgery. Using real- time PCR, relative expressions (compared to controls) of MC4R and AgRP mRNAs in the hypothalamus of rats were compared in four different groups of estrous cycle. The relative expression of MC4R mRNA in the hypothalamus of female rats during proestrus stage was higher than those in other stages (P=0.001). Despite a lower mean of relative expression of AgRP mRNA at proestrus stage, the relative expression of AgRP mRNA of the four stages of estrous cycle did not differ (P>0.05). In conclusion, changes in the relative expression of MC4R and AgRP mRNAs in four stages of rat estrous cycle indicated a stimulatory role of MC4R in the proestrus and preovulatory stages and an inhibitory role of AgRP in gonadotropin releasing hormone (GnRH) and LH secretions.
authors.affiliation: Department of Animal Sciences, School of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zandi
authors.affiliation: Department of Animal Sciences, School of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Jafarzadeh Shirazi
authors.affiliation: Transgenic Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Amin
authors.initials: A
authors.lastname: Tamadon
authors.affiliation: Department of Animal Sciences, School of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Amir
authors.initials: A
authors.lastname: Akhlaghi
authors.affiliation: Department of Animal Sciences, School of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Mohammad Saied
authors.initials: MS
authors.lastname: Salehi
authors.affiliation: Biotechnology Research Center, School of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Niazi
authors.affiliation: Biotechnology Research Center, School of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Moghadam
keywords: Melanocortin- 4 receptor; agouti- related peptide; estrous cycle; hypothalamus; rat