Effects of hormone replacement therapy and social stress on body fat distribution in surgically postmenopausal monkeys

Abstract

OBJECTIVE: To investigate the effects of hormone replacement therapy (HRT) and social stress on body fat distribution in an animal model of women's health, the female cynomolgus macaque (Macaca fascicularis). DESIGNaSUBJECTS: Adult female cynomolgus monkeys were ovariectomized and fed an atherogenic diet for two years while housed in social groups of 3 ± 8 monkeys each. Animals were then fed a lipid-lowering diet and randomized into four experimental groups: a baseline group which was necropsied immediately and not included in the study reported here, 26 females fed diet only (CONTROL), 22 females fed diet plus conjugated equine estrogens (CEE), and 21 females fed the diet plus CEE and medroxyprogesterone acetate (CEE MPA). Treatment lasted 30 months. MEASUREMENTS: During the last nine months of treatment, social status was determined three times at three month intervals. At the end of the study, whole body obesity and fat distribution patterns were determined using anthropometry and computerized tomography (CT). RESULTS: The addition of a progestin to the estrogen replacement regimen administered to surgically postmenopausal monkeys, increased all anthropometric and CT measures of obesity except intra-abdominal fat. HRT had no effect on patterns of fat distribution. Socially-dominant, ovariectomized females were more obese than subordinates using both anthropometric and CT measurements of whole body obesity. Dominant females were more likely to have their fat deposited centrally as measured anthropometrically. However, CT measures revealed a trend for dominants to preferentially deposit fat in the subcutaneous abdominal depot in contrast to subordinates who deposited fat in the intra-abdominal depot. CONCLUSIONS: The results of this study suggest that progestins, when administered in combination with estrogens, may increase fat deposition, particularly in subcutaneous depots. In addition, the social stress experienced by subordinate monkeys, may have mild effects on fat deposition patterns, even after removal of ovarian function as a factor. These observations may have implications for treatment recommendations in postmenopausal women. Lastly, CT may measure different characteristics of fat distribution than skinfolds and circumferences.

Social Stress, Visceral Obesity, and Coronary Artery Atherosclerosis in Female Primates

“…Briefly, animals were sedated (ketamine hydrochloride, 10 mg/kg BW and acepromazine maleate, 0.1 mg/kg BW, intramuscularly) and a single scan was done at the level of the umbilicus. Using a General Electric CT software package (General Electric, Stanford, CT) and a density range of −140 to −40 Hounsfield units to identify fat (19), total abdominal adipose tissue was quantified using the body margin as the outermost limit. VAT was identified as that lying within the margin of the transversus abdominis muscle.…”

“…SAT was calculated by subtracting VAT from total abdominal adipose tissue. A ratio was calculated to obtain an index of the relative distribution of adipose tissue in the visceral and subcutaneous abdominal compartments (VAT:SAT), and used as a measure of the relative amount of abdominal fat deposited in the visceral depot, hereafter termed relative visceral obesity (19).…”

Single acute stress-induced progesterone and ovariectomy alter cardiomyocyte contractile function in female rats

“…Some of the known risk factors for cardiovascular disease such as smoking, unhealthy diet, and behavioral and psychosocial stress have deleterious effects on the cardiovascular system via activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis (5-8). Acute restraint stress is a preferred and widely used method to induce physical stress in animal models (9).…”

Les 10es Entretiens de nutrition, institut Pasteur de Lille L’obésité, une maladie nutritionnelle ?

“…D'autres auteurs [3] ont confirmé ces données chez des singes macaques femelles ovariectomisées : les dominants pèsent plus lourds que les dominés, quel que soit le traitement hormonal substitutif, avec davantage de tissu adipeux abdominal total, sous-cutané et viscéral. Mais chez des femelles non castrées, ce sont les dominés qui ont une distribution centrale (viscérale) du tissu adipeux et un hypercortisolisme [3].…”

“…Mais chez des femelles non castrées, ce sont les dominés qui ont une distribution centrale (viscérale) du tissu adipeux et un hypercortisolisme [3].…”