Immunobiology of a synthetic luteinizing hormone receptor peptide 21-41

Chronic administration of atrial natriuretic peptide reduces testosterone production of testes in mice

The purpose of the present study was to examine the effect of the long-term administration of human atrial natriuretic peptide (ANP) on testosterone production in male mice. Twenty-five mice received ANP (20 ng/hour/g body weight) for 7 days via mini-osmotic pump, and the other group (n = 25) received twice-daily intraperitoneal injections. After death, levels of follicle-stimulating hormone, luteinizing hormone (LH), and testosterone in plasma, pituitary gland, and testis were measured by radioimmunoassay. Five mice from each group were examined histologically. In the minipump group, pituitary and plasma levels were significantly higher than those in the control group (771.2 +/- 43.6 vs 644.8 +/- 24.9 ng/mg and 6.7 +/- 0.6 ng/mg vs 2.5 +/- 0.6 ng/mL, respectively). In the intraperitoneal group, plasma LH levels were significantly higher in the ANP-treated group than that in control mice (9.6 +/- 0.3 ng/mg vs 3.8 +/- 0.5 ng/mL), whereas pituitary levels did not differ significantly. In both studies, testicular and plasma testosterone levels were significantly lower than those in control mice (P <.02). Histological features of the testes in ANP-treated mice revealed structural disorganization and inhibition of spermatogenesis. We conclude that the chronic administration of ANP may result in reduced testosterone production due to testicular damage.

Emergence of uterine pathology during accelerated biological aging in FSH receptor-haploinsufficient mice

A fully functional FSH receptor (Fshr) is required for ovarian follicular development and fertility. Fshr null females are sterile because of failure of follicular maturation, ovulation, and estrogen deficiency. Because Fshr-haploinsufficient females also begin to show age-dependent reproductive deficits that mimic biological aging, we have investigated the changes that occur in the uterus of these mice. The uterine weight in 12-month-old Fshr +/- mice increased 2-fold, and most retired breeders (those that stopped breeding earlier than our wild-type females) developed unilateral uterine masses that appeared similar to several abnormalities that also occur in women and associated with infertility. Curiously, there was a tendency for most of the abnormality to occur in the right horn. Up to 25% of the virgin Fshr-haploinsufficient mice also developed pathology. These transformations were not present in either wild-type mice or the estrogen-deficient Fshr null females at any age. In haploinsufficient females, estrogen and progesterone were reduced and testosterone was elevated in circulation by 1 yr. Fshr-haploinsufficient mice developed an imbalance of progesterone receptor isoforms A and B in the uterus. This alteration of progesterone receptors along with an increase in LH receptors in the uterus may contribute to the induction of high frequency of uterine pathology. Angiogenesis, vascular abnormality, and adenomyosis appeared to be increased in the uterine horn bearing pathological mass. The Fshr-haploinsufficient mice might help in understanding the molecular basis of induction of uterine pathology and tissue patterning.

Endocrine alterations and signaling changes associated with declining ovarian function and advanced biological aging in follicle-stimulating hormone receptor haploinsufficient mice

Reproductive aging in female mammals is characterized by a progressive decline in fertility due to loss of follicles and reduced ovarian steroidogenesis. In this study we examined some of the endocrine and signaling parameters that might contribute to a decrease in ovulation and reproductive performance of mice with haploinsufficiency of the FSH receptor (FSH-R). For this purpose we compared ovarian changes and hormone levels in FSH-R heterozygous (+/-) and wild-type mice of different ages (3, 7, and 12 mo). Hormone-induced ovulations in immature and 3-mo-old +/- mice were consistently lower. The number of corpora lutea (CL) were lower at 3 and 7 mo, and none were present in 1-yr-old +/- females. The plasma steroid and gonadotropin levels exhibited changes associated with typical ovarian aging. Plasma FSH and LH levels were higher in 7-mo-old +/- mice, but FSH levels continued to rise in both genotypes by 1 yr. Serum estradiol and progesterone were lower in +/- mice at all ages, and testosterone was several-fold higher in 7-mo-old and 1-yr-old +/- mice. Inhibin alpha (Western blot) appeared to be lower in +/- ovaries at all ages. FSH-R (FSH* binding) declined steadily from 3 mo and reaching the lowest point at 1 yr. LH receptor (LH* binding) was high in the 1-yr-old ovary, and expression was localized in the stroma and interstitial cells. Our findings demonstrate that haploinsufficiency of the FSH-R gene could cause premature exhaustion of the gonadal reserves previously noted in these mice. This is accompanied by age-related changes in the hypothalamic-pituitary axis. As these features in our FSH-R +/- mice resemble reproductive failure occurring in middle-age women, further studies in this model might provide useful insights into the mechanisms underlying ovarian aging.