Kam, Kyung-Yoon; Shin, Seung Yub; Han, Seong Kyu; Li, Long Hua; Chong, Wonee; Baek, Dae Hyun; Lee, So Yeong; Ryu, Pan Dong

Korean Journal of Veterinary Research 2004;44(2):207-215.

Kyung-Yoon Kam¹, Seung Yub Shin², Seong Kyu Han³, Long Hua Li², Wonee Chong², Dae Hyun Baek², So Yeong Lee², Pan Dong Ryu²

¹Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard Medical School
²Department of Pharmacology, College of Veterinary Medicine and School of Agricultural Biotechnology, Seoul National University
³Center for Neuroendocrinology and Department of Physiology, School of Medical Sciences, The University of Otago

Effect of adrenalectomy on gene expression of adrenoceptor subtypes in the hypothalamic paraventricular nucleus

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Abstract

It is well known that the hypothalamic-pituitary-adrenocortical (HPA) axis is under the negative feedback control of adrenal corticosteroids. Previous studies have suggested that glucocorticoids can regulate neuroendocrine cells in the paraventricular nucleus (PVN) by modulating catecholaminergic transmission, a major excitatory modulator of the HPA axis at the hypothalamic level. But, the effects of corticosteroids on the expression of adrenoceptor subtypes are not fully understood. In this work, we examined mRNA levels of six adrenoceptor subtypes (${alpha}_{1A}$, ${alpha}_{1B}$, ${alpha}_{2A}$, ${alpha}_{2B}$, ${eta}_1$ and ${eta}_2$) in the PVN of normal and adrenalectomized (ADX) rats. Total RNA ($2.5{mu}g$) was extracted from PVN micropunches of brain slices ($500{mu}m$) and analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The levels of corticotropin-releasing hormone (CRH) mRNA were increased in the ADX rats relative to normal rats, indicating that the PVN had been liberated from the negative feedback of corticosteroids. Among the six adrenoceptor subtypes examined, mRNA levels for ${alpha}_{1B}$- and ${eta}_1$-adrenoceptors were increased, but the level for ${eta}_2$-adrenoceptors was decreased in the ADX rats. The mRNA levels for the other three subtypes and for the general and neuronal specific housekeeping genes, glyceroaldehyde-3-phosphate dehydrogenase (GAPDH) and N-enolase, respectively, were not changed in the ADX rats. In conclusion, the results indicate that adrenal steroids selectively regulate the gene expression of adrenoceptor subtypes in the PVN.

Key Words: corticosteroid, RT-PCR, micropunch, corticotropin-releasing hormone