Roles for the sympathetic nervous system, renal nerves, and CNS melanocortin-4 receptor in the elevated blood pressure in hyperandrogenemic female rats

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2015-04, Vol.308 (8), p.R708-R713
• Main Authors: Maranon, Rodrigo, Lima, Roberta, Spradley, Frank T, do Carmo, Jussara M, Zhang, Howei, Smith, Andrew D, Bui, Elizabeth, Thomas, R Lucas, Moulana, Mohadetheh, Hall, John E, Granger, Joey P, Reckelhoff, Jane F
• Format: Article
• Language: English
• Subjects: Adrenergic Antagonists - pharmacology; Animals; Arterial Pressure - drug effects; Blood pressure; Cardiovascular disease; Dihydrotestosterone; Disease Models, Animal; Female; Gene expression; Hormone Antagonists; Hormones, Reproduction and Development; Hyperandrogenism - chemically induced; Hyperandrogenism - complications; Hyperandrogenism - drug therapy; Hyperandrogenism - metabolism; Hyperandrogenism - physiopathology; Hypertension; Hypertension - etiology; Hypertension - metabolism; Hypertension - physiopathology; Hypertension - prevention & control; Hypothalamus - drug effects; Hypothalamus - metabolism; Hypothalamus - physiopathology; Kidney - innervation; Neural Control; Physiology; Polycystic ovary syndrome; Polycystic Ovary Syndrome - chemically induced; Polycystic Ovary Syndrome - complications; Polycystic Ovary Syndrome - drug therapy; Polycystic Ovary Syndrome - metabolism; Polycystic Ovary Syndrome - physiopathology; Rats, Sprague-Dawley; Receptor, Melanocortin, Type 4 - antagonists & inhibitors; Receptor, Melanocortin, Type 4 - metabolism; Rodents; Signal Transduction; Sympathectomy; Sympathetic Nervous System - drug effects; Sympathetic Nervous System - physiopathology; Sympathetic Nervous System - surgery; Time Factors
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00411.2014

Women with polycystic ovary syndrome (PCOS) have hyperandrogenemia and increased prevalence of risk factors for cardiovascular disease, including elevated blood pressure. We recently characterized a hyperandrogenemic female rat (HAF) model of PCOS [chronic dihydrotestosterone (DHT) beginning at 4 wk of age] that exhibits similar characteristics as women with PCOS. In the present studies we tested the hypotheses that the elevated blood pressure in HAF rats is mediated in part by sympathetic activation, renal nerves, and melanocortin-4 receptor (MC4R) activation. Adrenergic blockade with terazosin and propranolol or renal denervation reduced mean arterial pressure (MAP by telemetry) in HAF rats but not controls. Hypothalamic MC4R expression was higher in HAF rats than controls, and central nervous system MC4R antagonism with SHU-9119 (1 nmol/h icv) reduced MAP in HAF rats. Taking a genetic approach, MC4R null and wild-type (WT) female rats were treated with DHT or placebo from 5 to 16 wk of age. MC4R null rats were obese and had higher MAP than WT control rats, and while DHT increased MAP in WT controls, DHT failed to further increase MAP in MC4R null rats. These data suggest that increases in MAP with chronic hyperandrogenemia in female rats are due, in part, to activation of the sympathetic nervous system, renal nerves, and MC4R and may provide novel insights into the mechanisms responsible for hypertension in women with hyperandrogenemia such as PCOS.