Developmental and Steroidogenic Effects on the Gene Expression of RFamide Related Peptides and their Receptor in the Rat Brain and Pituitary Gland

Abstract

RFamide related peptides (RFRPs) have been extensively implicated in the neuroendocrine control of reproduction. While steroid hormones strongly regulate the closely-related kisspeptin gene and protein expression, the regulation of RFRPs or their receptor by steroid hormones is almost unknown. The present study aimed to quantify relative levels of RFRP and Kiss1 gene expression and their G protein-coupled receptors (GPR147 and GPR54, respectively) in various brain areas and the pituitary gland, and to determine the effects of differing levels of oestradiol and pubertal development on levels of these gene products. In Experiment 1, the treatment groups examined were: dioestrus, ovariectomised and ovariectomised with replacement oestradiol to induce a preovulatory-like luteinising hormone surge. Micropunched brain regions and whole pituitary glands were processed for measurement of RFRP, Kiss1, GPR147 and GPR54 mRNA by quantitative reverse transcriptase-polymerase chain reaction. As expected, Kiss1 gene expression was low in the rostral periventricular area of the third ventricle of ovariectomised animals, whereas levels were highest in the arcuate nucleus in this situation. No such oestrogenic effects were observed for RFRP gene expression. GPR147 gene expression was highest in the rostral periventricular region of the third ventricle. The levels of GPR147 and GPR54 mRNA were markedly lower in the pituitary gland than in the hypothalamic regions, and RFRP and Kiss1 mRNA were virtually undetectable in the pituitary gland. These data imply that the actions of RFamides are likely to be predominantly central in nature. In Experiment 2, hypothalamic RFRP and GPR147 mRNA levels were measured in male and female rats aged 2, 4, 6 and 8 weeks. In females, RFRP gene expression increased with developmental age, peaking around the time of puberty, whereas in males gene expression increased between 2 and 4 weeks of age. These results suggest a role in the regulation of adult reproduction rather that prepubertal infertility.

Molecular, cellular, morphological, physiological and behavioral aspects of gonadotropin-inhibitory hormone

“…However, both parameters are significantly increased in female rats from peripuberty to adulthood (Jørgensen et al, 2014). Quennell et al (2010) measured hypothalamic GnIH and GPR147 mRNA levels in male and female rats aged 2, 4, 6 and 8 weeks. In females, GnIH gene expression increases with developmental age, peaking around the time of puberty, whereas gene expression increases between 2 and 4 weeks of age in males (Quennell et al, 2010).…”

“…Quennell et al (2010) measured hypothalamic GnIH and GPR147 mRNA levels in male and female rats aged 2, 4, 6 and 8 weeks. In females, GnIH gene expression increases with developmental age, peaking around the time of puberty, whereas gene expression increases between 2 and 4 weeks of age in males (Quennell et al, 2010). Iwasa et al (2012) also investigated changes in GnIH mRNA and GPR147 mRNA levels in the rat hypothalamus during development.…”

A simple method for isolation of the anteroventral periventricular and arcuate nuclei of the rat hypothalamus

“…Dissection of the hypothalamus for using in RT-PCR has been reported before; hypothalamus was dissected to the boundaries as the followings: rostral to the anterior border of the optic chiasm (Figure 1, AA), caudal to the posterior border of the mammillary body (Figure 1, BB) dorsal to the ventral border of the thalamus (Figure 3, AA), and 2mm lateral to the third ventricle (Figure 3, BB). [11] Punch method was used for sampling of the nuclei. Bilateral punches (1 mm in diameter) from the medial preoptic area, which included the AVPV, were taken from Bregma +0.2 to Bregma -0.4; a single midline punch (1 mm diameter) was taken from Bregma -1.7 to Bregma -3.9 to include both Arc nuclei.…”

Activation of Neuropeptide FF Receptors by Kisspeptin Receptor Ligands

“…However, it is envisaged that pubs.acs.org/acsmedchemlett the LH level would be highly regulated by the expression level of these receptors or ligands, the projection pattern of neurons, and/or by some unknown mechanisms. 29 Further investigation examining the kisspeptin receptor distributions should reveal the regulatory mechanism of the highly sophisticated LH secretion process as well as the molecular basis of incomplete hypogonadism in GPR54 knockout mice. 30 In conclusion, the investigation of the selectivity profiles of GPR54 agonist peptides revealed unprecedented interactions between kisspeptins and NPFFRs.…”