Differences in adrenocortical secretory and gene expression responses to stimulation in vitro by ACTH or prolactin between high- and low-avoidance Hatano rats

Original Research Report

Sukanya Jaroenporn Department of Basic Veterinary Science, The United School of Veterinary Sciences, Gifu University, Gifu, Gifu 501-1193, Japan; Laboratory of Veterinary Physiology, Faculty of Agriculture, Department of Veterinary Medicine, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan

Kentaro Nagaoka Laboratory of Animal Breeding and Reproduction, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan

Ryo Ohta Safety Testing Laboratory, Research Administration, Hatano Research Institute, Food and Drug Safety Center, Hatano, Kanagawa 257-8523, Japan

Mariko Shirota Safety Testing Laboratory, Research Administration, Hatano Research Institute, Food and Drug Safety Center, Hatano, Kanagawa 257-8523, Japan

Gen Watanabe Department of Basic Veterinary Science, The United School of Veterinary Sciences, Gifu University, Gifu, Gifu 501-1193, Japan; Laboratory of Veterinary Physiology, Faculty of Agriculture, Department of Veterinary Medicine, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan

Kazuyoshi Taya Department of Basic Veterinary Science, The United School of Veterinary Sciences, Gifu University, Gifu, Gifu 501-1193, Japan; Laboratory of Veterinary Physiology, Faculty of Agriculture, Department of Veterinary Medicine, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, JapanCorrespondence[email protected]

Abstract

Rats of the Hatano high-avoidance (HAA) and low-avoidance (LAA) strains have been genetically selected on the basis of their two-way active avoidance behavior, and have different endocrine responses to stress. The present study focused on the adrenal steroid hormone responses of the Hatano strains and identifies differences in regulation of the adrenal cortex in vitro of HAA and LAA rats. Although incubation with prolactin (PRL) and/or adrenocorticotrophic hormone (ACTH) resulted in a dose-dependent increase of corticosterone and progesterone release by adrenal cells from both HAA and LAA male rats, the responses were markedly increased for adrenal cells from LAA rats as compared with HAA rats. This finding suggested that adrenal glands of HAA rats are less sensitive to PRL and/or ACTH than adrenals from LAA rats. Several possible intra-adrenal regulators were investigated. The basal level of expression of steroidogenic acute regulatory protein (StAR) and the long form of the PRL receptor (PRLR-L) mRNAs was higher in adrenals of LAA rats. ACTH treatment of adrenal cells from HAA rats resulted in statistically significant increases in melanocortin receptor 2 (MC2R) mRNA expression, while neither ACTH nor PRL altered MC2R mRNA expression in adrenal cells of LAA rats. Conversely, the increase in PRLR-L mRNA expression induced by PRL was observed only in adrenal cells from LAA rats. Treatment of adrenal cells with PRL and/or ACTH increased the expression of StAR and CYP11A1 mRNAs for both Hatano strains. However, the induction of StAR mRNA expression was higher in LAA rats, but the CYP11A1 response was lower. These findings indicate that adrenal cells of the LAA strain have higher sensitivity to secretagogues than those of the HAA strain. These results suggest that PRL may also be important in stimulating secretion of adrenal steroid hormones.

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Differences in adrenocortical secretory and gene expression responses to stimulation in vitro by ACTH or prolactin between high- and low-avoidance Hatano rats

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Differences in adrenocortical secretory and gene expression responses to stimulation in vitro by ACTH or prolactin between high- and low-avoidance Hatano rats

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