Angiotensin II influences ovarian follicle development in the transgenic (mRen-2)27 and Sprague-Dawley rat

Abstract

There is accumulating evidence that local reninangiotensin systems (RASs) influence cell growth and organ function in a variety of tissues including the ovary. The first aim of this study was to characterise the cellular location of RAS components in the rat ovary. This was facilitated by the use of the hypertensive transgenic (mRen-2)27 rat which overexpresses renin and angiotensin in extra-renal tissues. Comparisons were made with normal Sprague-Dawley (SD) rats. The second aim was to determine if the upregulated RAS of the transgenic (mRen-2)27 rat and infusion of angiotensin II (ANG II) in SD rats influences follicle number and litter size. Gene expression, immunohistochemical and autoradiographic techniques were used to identify a discrete RAS including ANG II receptors in the ovarian stroma, follicles (particularly atretic) and to a lesser extent corpora lutea. The RAS at these sites was most abundant in homozygous (HMZ) followed by heterozygous (HTZ) (mRen-2)27 rats and then SD rats. Large antral and preovulatory follicles and litter size were reduced in (mRen-2)27 rats. In HMZ (mRen-2)27 rats and SD rats infused with ANG II, angiotensin 1a (AT 1a ) receptor mRNA in the ovarian stroma was lower than control SD rats and was associated with a reduction in large antral and preovulatory follicles. These findings indicate that upregulation of the ovarian RAS in the rat influences follicular development and, potentially, reproductive capacity.

Prevention of metabolic disorders and reproductive performance deficits by the blockade of Angiotensin II AT1 receptor in female rats fed with cafeteria diet

“…Moreover, infusion of Ang II in rats is also associated with a reduction in antral and preovulatory follicles [46]. Given the increased activity of the reninangiotensin system in obesity [47] and reduced follicular development in ovaries of obese female mice [48], we postulate that higher levels of Ang II could be contributing to the reduction in ovarian follicle development in obese rats.…”

Angiotensin II Signaling Promotes Follicle Growth and Dominance in Cattle

“…Several lines of evidence in rats and rabbits also suggest that AngII alters the fate of the growing follicle, driving it toward atresia; the type 2 receptor occurs on atretic but not healthy granulosa cells (12)(13)(14), receptor binding increased with the induction of granulosa apoptosis in vitro (15), and treatment of granulosa cells with AngII induced DNA fragmentation and decreased estradiol secretion (16,17). This, however, may not be true in other species.…”

Changes in the Messenger RNA Expressions of the Endothelin-1 and Angiotensin Systems in Mature Follicles of the Superovulated Bovine Ovary

“…In addition, expression of the AT2R gene drastically decreased during the periovulatory period compared with the other periods. A previous study using hypertensive transgenic (mRen-2)27 homozygous and heterozygous rats, which overexpress renin and angiotensin in extrarenal tissues, reported that AT1R expression is reduced in (mRen-2)27 homozygous rats, and this decrease may be a result of elevated levels of Ang II in this strain compared with (mRen-2)27 heterozygous rats [34]. In addition, high levels of Ang II downregulate Ang II receptors in rat cultured granulosa cells [35] and aortic vascular smooth muscle cells [36].…”