Immunoreactive GnRH type I receptors in the mouse and sheep brain

Abstract

Gonadotropin Releasing Hormone-I (GnRH) has been implicated in an array of functions outside the neuroendocrine reproductive axis. Previous investigations have reported extensive GnRH binding in numerous sites and this has been supported by in situ hybridization studies reporting GnRH receptor mRNA distribution. The present study on mice and sheep supports and extends these earlier investigations by revealing the distribution of cells immunoreactive for the GnRH receptor. In addition to sites previously shown to express GnRH receptors such as the hippocampus, amygdala and the arcuate nucleus, the improved resolution afforded by immunocytochemistry detected cells in the mitral cell lay of the olfactory bulb as well as the central grey of the mesencephalon. In addition, GnRH receptor immunoreactive neurons in the hippocampus and mesencephalon of the sheep were shown to colocalize with estrogen receptor beta. Although GnRH may act at some of these sites to regulate reproductive processes, evidence is accumulating to support an extra-reproductive role for this hypothalamic decapeptide.

Spatial memory is impaired by peripubertal GnRH agonist treatment and testosterone replacement in sheep

“…The hippocampus is central to spatial learning and memory, and Albertson et al (2009) has demonstrated that there are GnRHR type I immunoreactive cells in the CA1 to 4 regions, as well as the dentate gyrus, of the ovine hippocampus. Nuruddin et al (2013b) reported that peripubertal blockade with GnRHa, resulted in sex specific changes in hippocampal (CA1 to 3) mRNA expression.…”

“…Long-term GnRHa-treatment is therefore used in pediatric human medicine as a co-treatment for conditions such as early onset gender dysphoria, central precocious puberty, idiopathic short stature, growth hormone deficiency, congenital adrenal hyperplasia, and severe hypothyroidism (Carel et al, 2009, Hembree et al, 2009). GnRHR expression and GnRH binding are present in extra-pituitary tissues (Hapgood et al, 2005), including brain regions such as the hippocampus and other limbic structures (Jennes et al, 1997, Albertson et al, 2009, Skinner et al, 2009, Schang et al, 2010). Therefore, long-term GnRHa-treatment may have additional cognitive and behavioral effects, due to a blockade of GnRH signaling outside the HPG axis (Carel et al, 2009, Hembree et al, 2009).…”

Gonadotropin-releasing hormone modulates cholesterol synthesis and steroidogenesis in SH-SY5Y cells

“…CNS and the immune system), suggesting the presence of miniature HPG and HPA axis homologs that are able to autonomously regulate local steroidogenesis [15]. GnRH receptors (GnRHRs) have been localized in many regions of the brain such as the hippocampus and cortex and detected in human neuronal cell models like the neuroblastoma SH-SY5Y and M17 cells [16,17]. In M17 cells GnRH induces an up-regulation of the LH␤ subunit [17] and LH mediates neuronal pregnenolone production increasing Steroidogenic Acute Regulatory protein (StAR) expression [18].…”

Identification of Single Nucleotide Polymorphism in GnRHR gene in Murrah bulls

“…It is expressed on the surface of pituitary gonadotrope cells as well as lymphocytes, breast, ovary and prostate (Albertson et al 2008). Genes of hypothalamic pituitary testicular axis plays a key role in male reproductive performance (Huhtaniemi and Alevizaki, 2007).…”