Alterations of estrous cycle, 3β hydroxysteroid dehydrogenase activity and progesterone synthesis in female rats after exposure to hypobaric hypoxia

Abstract

The underlying mechanism regulating hypoxia induced alteration in female steroid hormones is first time explored in this study. To understand the mechanistic approach, female Sprague- Dawley rats were exposed to acute and chronic hypobaric hypoxia (282 mm-Hg, ~7620 m, 6 hours, 3 and 7 days). Estrous cycle, body weight, plasma progesterone and estradiol levels, morphology, histology and two key steroidogenic enzymes: 3ß hydroxysteroid dehydrogenase (HSD) and 17ß HSD activity of ovary and adrenal gland were studied. A persistent diestrous phase and a significant decrease in body weight were found in chronic hypoxia groups. Histological study suggested degenerative changes in ovarian corpus luteum of 7 days chronic hypobaric hypoxia (7CHH) group and a declined percentage of adrenocortical cells in 3 days chronic hypobaric hypoxia (3CHH) and 7CHH groups. Plasma estradiol level was unaltered, but progesterone level was decreased significantly in all hypoxic groups. Ovarian 3ß HSD activity was decreased significantly with increasing days of hypoxic treatment along with a significantly low adrenal 3ß HSD activity in 7CHH. In conclusion, hypobaric hypoxia causes a state of low circulatory progesterone level in females likely due to the degenerative changes in the female ovarian and adrenal tissues together with low steroidogenic 3ß HSD enzyme activity.

Maca extracts and estrogen replacement therapy in ovariectomized rats exposed at high altitude

“…It is well known that high altitude impairs the female reproductive health 24 . Lowland women exposed to chronic or intermittent hypoxia have disturbances in the menstrual cycle more than native people from the highlands 25 .…”

“…Chronic hypobaric hypoxia causes an irregular estrous cycle in rats, decreases sex hormone levels, and prolongs diestrous phase 24 . In OVX rats, the decrease in the number of cornified endometrial cells is directly correlated with an increase in circulating follicle‐stimulating hormone (FSH) and luteinizing hormone (LH), and with lower estrogen levels in plasma 41,42 .…”

“…It is well known that high altitude impairs the female reproductive health. 24 Lowland women exposed to chronic or intermittent hypoxia have disturbances in the menstrual cycle more than native people from the highlands. 25 In addition, highland native women presented with an increase in FSH level, early perimenopause, 26 delayed menarcheal, and advanced menopausal age.…”

“…Chronic hypobaric hypoxia causes an irregular estrous cycle in rats, decreases sex hormone levels, and prolongs diestrous phase. 24 In OVX rats, the decrease in the number of cornified endometrial cells is directly correlated with an increase in circulating follicle-stimulating F I G U R E 3 Effect of aqueous extract ofLepidium meyeniiWalp (red and black ecotype) on uterine function of OVX rats exposed at high altitude (n = 6). Basal tone (A, B), contractile response to 0.05 IU oxytocin (C, D) and 0.5 IU oxytocin (E, F); numbers show the maximum amplitude of contraction (A, C, E) and frequency of contractions (B, D, F).…”

Ursolic acid ameliorates hypobaric hypoxia‐induced skeletal muscle protein loss via upregulating Akt pathway: An experimental study using rat model

“…Control group rats were maintained in the normoxic chamber within the same laboratory. The chamber was opened for 15–20 minutes each day to change the bedding, replenish the diet, BW measurement of the rats and UA administration 2,24,25 …”