Differential regulation of glucocorticoid receptor messenger RNA (GR-mRNA) by maternal deprivation in immature rat hypothalamus and limbic regions

Abstract

Maternal deprivation (MDep) of neonatal rats significantly influences the hypothalamic-pituitary-adrenal (HPA) axis. This study hypothesized that GR-mRNA modulation constituted an early, critical mechanism for the acute effects of MDep on neuroendocrine stress-responses. GR-mRNA hybridization signal in hippocampal CA1, hypothalamic paraventricular nucleus (PVN) and frontal cortex was significantly reduced immediately following 24 h MDep. In amygdala, cingulate cortex, PVN and CA1, apparent gender-dependent MDep effects on GR-mRNA expression were observed, without significant differences in absolute levels. Thus, rapid, region-specific MDep effects on GR-mRNA expression in HPA-regulating areas are shown, consistent with involvement of GR-expression in mechanisms of MDep influence on HPA tone.

Fig. 1

GR-mRNA levels in maternally-deprived and non-deprived 9-day old rats. Following ISH for GR-mRNA, optical density was measured over paraventricular nucleus (PVN), hippocampal CA1, amygdaloid central nucleus (ACE), frontal-(FC) and cingulate cortex (CING). Autoradiographs show that GR-mRNA signal in PVN of deprived pups, (C) was lower than in controls (A). GR-mRNA signal over CA1 of controls (B) was stronger than in deprived pups (D). (E) Quantitative analysis of GR-mRNA signal. Mean ± S.E.M. of data from 12–22 sections from 4–6 brains per group; *p < 0.05.

Fig. 2

Gender-related effects of maternal deprivation on GR-mRNA levels. GR-mRNA levels did not differ between males and females in either controls (A) or deprived rats (B). (C) Reflects separate analyses of deprivation-effect on GR-mRNA levels in males and females. Gender-related differences in the magnitude of GR-mRNA level changes from the non-deprived baseline are apparent in ACE and PVN (see text for statistical considerations).