KeywordsGALP; Fos; food intake; body weight; AR-M1986 Galanin-like peptide (GALP) is a neuropeptide that is thought to act on the galanin receptors GALR1, GALR2 and GALR3. In rats intracerebroventricular (i.c.v.) injection of GALP has dichotomous actions on energy balance, stimulating feeding over the first hour, but reducing food intake and body weight at 24 h, as well as causing an increase in core body temperature. In mice GALP only induces an anorexic action, and its effects on core body temperature are unknown. One aim of this study was to determine the effects of GALP on core body temperature in mice. I.c.v. injection of GALP into conscious mice had no effect on feeding over 1 h, but caused a significant reduction in food intake and body weight at 24 h. It also caused an immediate drop in core body temperature that was followed by an increase in body temperature. To understand these different effects of GALP on energy balance in mice compared to rats, and to determine the involvement of GALR2 and GALR3, immunohistochemistry was performed to localise c-Fos, a marker of cell activation. I.c.v. injection of GALP induced c-Fos expression in the parenchyma surrounding the ventricles, the ventricular ependymal cells, and the meninges in mice and rats. GALP also induced cFos expression in the supraoptic nucleus, dorsomedial hypothalamic nucleus, lateral hypothalamus, and nucleus tractus solitarius in rats but not mice. Central administration of a GALR2/3 agonist in rats did not induce c-Fos in any of the brain regions that expressed this protein after GALP injection, and had no effect on food intake, body weight, and body temperature in rats or mice.These data suggest that GALP induces differential effects on energy balance and brain activity in mice compared to rats, which are unlikely to be due to activation of the GALR2 or GALR3 receptor.Galanin-like peptide (GALP) is a 60-amino-acid neuropeptide, originally isolated from porcine hypothalamus, that shares partial sequence homology with galanin (1). Amino acids 9-21 of GALP are identical to the first 13 amino acids of galanin, which are essential for galanin receptor activation. Whereas galanin is widely distributed in the central nervous system (CNS), GALP is found only in neurones of the hypothalamic arcuate nucleus, the median eminence, and pituicytes of the posterior pituitary in the rat (2-5), mouse (6) and primate (7). Europe PMC Funders Group Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts GALP has been described as a central mediator of feeding and metabolism and, like galanin, intracerebroventricular (i.c.v.) injection of GALP acutely increases feeding (over 30 min -1 h) in rats (8,9). However 24 h after GALP administration, a decrease in food intake is usually observed in rats, which is accompanied by a reduction in body weight (9,10). These longer-term anorectic actions of GALP are also observed after i.c.v. injection of this neuropeptide into mice (11-13). However, the acute orexigenic effects of GALP observed in the rat...

The transcription factor gene Egr1 is necessary for female fertility; EGR1 protein is an established molecular regulator of adult female gonadotroph function where it mediates GNRH-stimulated transcription of the Lhb gene. Recent studies have also implicated pituitary EGR1 in the mediation of other physiological signals indicating an integrative function. However, the role of EGR1 in males is less well defined and this uncertainty is compounded by the absence of cellular expression data in the male pituitary gland. The aim of this study, therefore, was to define the distribution of Egr1 gene expression in the adult male rat pituitary. To further this aim, we have evaluated cellular populations in a transgenic rat model (Egr1-d2EGFP), in which we demonstrate regulated green fluorescent protein (GFP) expression in EGR1C pituitary cells. Cellular filling by GFP enabled morphological and molecular differentiation of different populations of gonadotrophs; Egr1 transcription and LHB were highly co-localised in a major population of large cells but only minimally co-localised in small GFPC cells; the latter cells were shown to be largely (80%) composed of minority populations of GHC somatotrophs (9% of total GHC) and PRLC lactotrophs (3% of total PRLC). Egr1 transcription was not found in TSHC, ACTHC or SOX2C precursor cells and was only minimally co-localised in S-100bC folliculostellate cells. Our demonstration that the Egr1 gene is actively and selectively transcribed in a major sub-population of male LHBC cells indicates a largely conserved role in gonadotroph function and has provided a basis for further defining this role.

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