Effects of ovariectomy and steroid hormones on vaginal smooth muscle contractility

Abstract

The role of steroid hormones in regulating vaginal smooth muscle contractility was investigated. Rabbits were kept intact or ovariectomized. After 2 weeks, animals were continuously infused with vehicle or supraphysiological levels of testosterone (100 lg/day), or estradiol (200 lg/day), for an additional 2 weeks. The distal vaginal tissue was used to assess contractility in organ baths and changes in tissue structure were assessed by histology. Ovariectomized animals infused with vehicle exhibited significant atrophy of the muscularis and decreased epithelial height, resulting in thinning of the vaginal wall. Estradiol infusion increased epithelial height, comparable to that of intact animals, but only partially restored the muscularis layer. In contrast, testosterone infusion completely restored the muscularis layer, but only partially restored the epithelial height. In vaginal tissue strips contracted with norepinephrine and treated with bretylium, electrical field stimulation (EFS) caused frequency-dependent relaxation that was slightly attenuated with vehicle, significantly inhibited with estradiol and significantly enhanced with testosterone. VIP-induced relaxation was slightly attenuated in tissues from vehicle and estradiol-infused groups, but was enhanced in tissues from testosterone-infused animals. Contraction elicited by EFS or exogenous norepinephrine was not significantly altered with ovariectomy or steroid hormone infusion when data were normalized to potassium contraction. However, the tissue from testosterone-infused animals developed significantly greater contractile force to norepinephrine. These observations suggest that steroid hormones may be important regulators of vaginal tissue structure and contractility.

Restoration of Vaginal Epithelial Atrophy in Ovariectomized Rats with Sex Steroid Hormones

“…The decrease in glycogen production would not maintain the low pH level needed in the vaginal fluA non significant muscular atrophy was confirmed in the vaginal muscularis structure of all ovariectomized and both control rat groups resembled results established by previous study [24]. However, some earlier reports showed significant greater atrophy in the muscularis layers after ovariectomy in rabbits and menopause in women, respectively [21,28]. This disagreement may be attributed to the relatively short term after ovariectomy during the present study (4 weeks), which did not allow significant changes in the muscularis layers to emerge in ovariectomized animals.…”

“…Menopause was responsible for inducing a reduction in the number of vaginal epithelial layers, and loss of intermediate cells, represented by an overall reduction in epithelial height [20]. Laboratory studies, showed that ovariectomized rabbits, rats, and nonhuman primates had significant decrease in vaginal epithelial height and smooth muscle tissues [5,6,19,21].…”

Histometric Parameters of Uterus and Vagina in Breeder Female Rabbits on the Day After Weaning According to the Ordinal Number of Parturitions

“…Both hormones regulate growth, proliferation and secretion function of reproductive tract epithelial cells. Likewise, the changes in concentration of these hormones during the estrus cycle induce hemodynamic changes in the vascular tissue that result in the increment of permeability of blood vessels and humid weight of the uterus (Kim et al, 2004;Vinci et al, 2010).…”

Pemberian Kombinasi Estrogen Progesteron dan Testosteron Meningkatkan Ekspresi Messenger Ribonucleaic Acid (mRNA) Reseptor Estrogen Alpha dan Androgen pada Vagina Tikus Wistar (Rattus norvegicus) Dewasa yang Diovarektomi

“…Penurunan hormon ini juga diikuti dengan penurunan jumlah messenger ribonucleaic acid (mRNA) reseptor estrogen alpha (ERα) dan androgen (AR) yang menyebabnya kemampuan untuk menangkap hormon steroid menjadi menurun pada tikus. 3 Penurunan jumlah sekresi hormon dan sintesa protein reseptornya menyebabkan terjadi masalah kesehatan yang meliputi gejala vasomotor, somatik, urogenital, psikologis, osteoporosis dan gangguan fungsi seksual. Masalah pada vagina diantaranya vagina menjadi kering, atrofi dan dypareunia, penurunan libido dan gangguan lubrikasi vagina merupakan gejala yang menyebabkan menurunnya kualitas seksual pada masa menopause.…”

“…3 Metilasi promoter-CpG island semakin dipercaya sebagai salah satu perubahan molekular yang dapat diobservasi pada proses penuaan. Metilasi dari region yang kaya akan CpG pada bagian promoter gen merupakan perubahan epigenetik yang menyebabkan inaktivasi transkripsi gen tanpa berhubungan dengan abnormalitas gen.…”