Effects of gender, gonadectomy and sex hormones on growth and plasma cholesterol level in rats.
OBJECTIVE
No studies have clearly demonstrated how sex hormones are involved in the observed gender difference in growth and plasma cholesterol levels in animals fed hypercholesterolemic diets. This study was conducted to determine the effects of gender, gonadectomy (GNX), and sex hormones on growth, plasma cholesterol and cortisol levels in Sprague-Dawley rats.


METHODS
In the first of two experiments, equal numbers of male and female 4-week-old rats were divided into three groups: sham-operated control, GNX, or GNX + 17alpha-methyltestosterone (MT). The rats were fed a hypercholesterolemic diet for 4 weeks. In a second experiment, 24 GNX females were equally divided into three groups: control, 17beta-estradiol (E(2)), or MT. These rats were fed a normocholesterolemic diet for 3 weeks.


RESULTS
The average total plasma cholesterol level in female rats was twice that in male rats. MT administration to GNX male and GNX female rats decreased plasma cholesterol levels by 23 and 45%, respectively. Weekly intramuscular injection of E(2) markedly suppressed growth while increasing plasma cortisol levels in GNX female rats.


CONCLUSIONS
Testosterone decreases plasma cholesterol levels in rats fed a hypercholesterolemic diet and E(2) suppresses growth of rats, inducing the secretion of hormones that increase with stress.
Lee
Chong-Eon
CE
Department of Animal Biotechnology, Cheju National University, Jeju, Korea.
Kang
Jung-Suk
JS
Kim
Kyu-Il
KI
D000818:Animals; D002784:Cholesterol / Q000097:blood*; D002791:Cholesterol, Dietary / Q000008:administration & dosage*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006128:Growth / Q000187:drug effects*; D006854:Hydrocortisone / Q000097:blood*; D007273:Injections, Intramuscular; D008297:Male; D008777:Methyltestosterone / Q000494:pharmacology*; D009919:Orchiectomy; D010052:Ovariectomy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012737:Sex Factors; D013739:Testosterone / Q000097:blood
D002791:Cholesterol, Dietary; D013739:Testosterone; D004958:Estradiol; D002784:Cholesterol; D008777:Methyltestosterone; D006854:Hydrocortisone