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. 1994 Dec;135(6):2364-8.
doi: 10.1210/endo.135.6.7988418.

Corticotropin-releasing hormone mediates the response to cold stress in the neonatal rat without compensatory enhancement of the peptide's gene expression

S J Yi  1 , T Z Baram
Affiliations

Corticotropin-releasing hormone mediates the response to cold stress in the neonatal rat without compensatory enhancement of the peptide's gene expression

S J Yi et al. Endocrinology. 1994 Dec.

Abstract

A variety of stressors activate the hypothalamic-pituitary-adrenal axis, with secretion and compensatory enhanced synthesis of hypothalamic corticotropin-releasing hormone (CRH). Whether CRH is a major effector in the stress response of the neonatal rat and whether the peptide's gene expression is subsequently up-regulated are not fully understood. We studied the effect of cold-separation stress on plasma corticosterone (CORT) levels and CRH messenger RNA (CRH-mRNA) abundance in the paraventricular nucleus. Rats (4-16 days old) were subjected to maximal tolerated cold-separation. CORT and CRH-mRNA abundance were measured before and at several time points after stress. Cold-separation stress resulted in a significant plasma CORT increase in all age groups studied. This was abolished by the administration of an antiserum to CRH on both postnatal days 6 and 9. CRH-mRNA increased in rats aged 9 days or older, but not in 6-day-old rats, by 4 h after stress. These results suggest the presence of robust CRH-mediated adrenal responses to cold-separation stress in neonatal rats. Before postnatal day 9, however, the compensatory increase in CRH-mRNA abundance is minimal.

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Figures

Fig. 1
Fig. 1
A composite of plasma CORT time courses in response to cold-separation stress in postnatal (PND) rats of different ages. See text for experimental paradigm. Values are the mean ± SEM of six to eight rats per group. For all age groups, 60 min values are significantly different from prestress levels (P < 0.05). On PND 6, the 40 min value is significantly elevated as well (P < 0.05).
Fig. 2
Fig. 2
Effect of passive immunization against CRH on cold-separation stress-induced plasma corticosterone elevation in 6-day-old rats (n = 6/group). Bars indicate SEs. *, Significantly different from control (P < 0.05); **, significantly different from cold plus NSS stress (P < 0.05).
Fig. 3
Fig. 3
Effect of passive immunization against CRH on cold-separation stress-induced plasma CORT elevation in 9-day-old rats (n = 4/group). Bars indicate SEs. *, Significantly different from control (P < 0.05); **, significantly different from cold plus NSS (P < 0.05).
Fig. 4
Fig. 4
Time course of compensatory enhanced CRH-mRNA abundance in 16-day-old rats subjected to cold-separation (Cold-Sep) stress. See text for details of ISH and semiquantitative analysis. Shown are the mean and SE of at least four rats. *, Significantly different from control (P < 0.05).
Fig. 5
Fig. 5
Effect of cold-separation (Cold-Sep) stress on CRH mRNA in the PVN of 6-, 9-, and 16-day-old rats. Pups were subjected to age-appropriate maximal tolerated cold stress (see text). CRH mRNA was determined using ISH. Values (mean ± SEM) were derived as detailed in Materials and Methods. *, Significantly different from control (P < 0.05).
Fig. 6
Fig. 6
Darkfield photomicrograph of ISH for CRH mRNA in the PVN of 9-day-old rats. A, Control; B, cold-stressed. III, Third ventricle. Bar = 10 μm.
See this image and copyright information in PMC

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