Effects of Lepidium sativum supplementation on growth and gonadotropins secretion in ovariectomized, estrogen-implanted rabbits

摘要

Objective: To test the effects of dietary supplementation of Lepidium sativum (LS) seed powder on growth performance and gonadotropins secretion in ovariectomized, estradiol-implanted rabbits. Methods: Ovariectomized, estradiol-implanted Chinchilla rabbits were assigned into four experimental groups: LS seed powder was included into normal rabbit chow at 0％ (control), 5％ (low), 7％ (mid) and 10％ (high) w/w. Experimental feed and water were given ad-libitum for 3 weeks. Weekly body weights and daily feed intake of rabbits were recorded. Twenty-one days post-feeding, blood samples were collected at 15-minute interval for 3 h (PeriodⅠ) after which 2.5 μg gonadotropin-releasing hormone (GnRH) was injected intravenously and the sampling continued for another hour (PeriodⅡ). Plasma was harvested and analyzed for luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by radioimmunoassay. Results: Feed intake was significantly (P<0.05) increased in LS-supplemented rabbits. However, the increase in feed intake did not result in significant body weight gain. LS seed supplementation significantly (P<0.001) increased mean plasma LH dose-dependently from the low- to the mid-LS level and then decreased LH at the high-LS level. LS supplementation increased (P<0.001) plasma FSH secretion. Injection of GnRH had no effect on plasma LH, however significantly (P<0.05) decreased overall plasma FSH secretion. Conclusions: LS seed supplementation stimulates feed intake and gonadotropins secretion in rabbits. Gonadotropins effect may be mediated through LS seeds phytosterols through the activation of estrogen receptors thereby producing agonistic effects resulting in LH and FSH secretion. The differential responses of gonadotropins to GnRH in LS-supplemented rabbits suggest differential regulation of the synthesis and secretion of these gonadotropins.