Adrenal alpha(2)-adrenergic receptors in the aging normotensive and spontaneously hypertensive rat

作者：Moura Eduardo; Pinto Carina Esteves; Serrao Maria Paula; Afonso Joana; Vieira Coelho Maria Augusta^*

来源：Neurobiology of Aging, 2012, 33(5): 969-978.

DOI：10.1016/j.neurobiolaging.2010.06.021

• Aging
• Alpha2-adrenergic receptor
• Adrenal medulla
• Epinephrine
• Spontaneously hypertensive rat
• Nicotinic receptors

This study investigates alpha(2)-adrenergic receptor (alpha(2)AR) mediated feedback inhibition of catecholamine release from the adrenal medulla of adult (52 weeks) and old (98 weeks) spontaneously hypertensive rats (SHR) and normotensive controls Wistar Kyoto (WKY) rats. Adrenal epinephrine content as well as the spontaneous and the nicotinic-evoked release of epinephrine were similar between adult SHR and WKY rats. Aging produced a significant reduction in epinephrine synthesis in WKY rats. In contrast, in SHR aging produced a significant increase in epinephrine release without significant changes in epinephrine synthesis. The alpha(2)AR agonist medetomidine abolished (80-90% inhibition) the nicotinic-evoked release of epinephrine in adult SHR and WKY rats. With aging, this effect was unaltered in WKY rats but was significantly decreased in SHR (30% inhibition). Adrenal alpha(2A)AR mRNA levels were significantly reduced in old SHR compared with age matched WKY rats. In conclusion, in aging the alpha(2)AR mediated feedback inhibition of epinephrine release from the adrenal medulla is preserved in WKY rats but compromised in SHR, resulting in increased epinephrine release.

• 出版日期2012-5