Aromatase expression is linked to estrogenic sensitivity of periurethral muscles in female rabbits

Abstract

Beyond its role in the conversion of androgens to estrogens, the expression of aromatase could influence on the estrogenic signalling in targeted tissues. Considering the well-defined biochemical and physiological differences between the pubococcygeus (Pcm) and bulbospongiosus (Bsm) muscles in female rabbits, it is presently hypothesized that the aromatase expression is differentially linked to the estrogen sensitivity of each muscle. To this end, serum estradiol levels and the aromatase expression, presence of ERα and ERβ and morphometry were evaluated in the Pcm and Bsm of female rabbits allocated in control, ovariectomized (OVX) and OVX treated with estradiol benzoate (OVX + EB) groups. Aromatase expression was high in the Pcm. Independently to serum estradiol, ovariectomy increased aromatase expression in the Pcm while decreased it in the Bsm. The EB treatment avoided the effect of ovariectomy only in the Pcm. The number of immunoreactive nuclei anti-ERα and anti-ERβ was high in the Pcm of OVX and OVX + EB rabbits, while those in the Bsm remained unchanged. The number of peripheral nuclei per fibre and the cross-sectional area-to-myonucleus ratio were modified only in the Pcm. Our findings support aromatase expression in the Pcm, and Bsm of rabbits is differentially linked to estrogenic sensitivity of each muscle.

Role of Estrogens in the Size of Neuronal Somata of Paravaginal Ganglia in Ovariectomized Rabbits

“…Present findings support that a great extragonadal aromatization is linked to the recovery of serum E2 levels in chronically ovariectomized (5-month) rabbits [20]. As described for female rats [33], non-gonadal peripheral organs in which androgens are metabolized to estrogens should be further elucidated in rabbits.…”

“…Serum T was measured by using commercially available EIA kits (Cayman Chemical Company) as described elsewhere [27]. Moreover, the log E2/T ratio was calculated to estimate the extent in which extragonadal aromatization could explain the recovery of serum E2 levels [20, 30]. …”

“…Approximately 150 mg of ovarian and vaginal tissues for each rabbit was disrupted using an electronic homogenizer (TissueTearor, BioSpec Products, Inc.) in lysis buffer (20 mM tris-HCl pH 7.4, 100 mM glycine, 100 mM NaCl, 0.1% triton X-100, 1 mM phenylmethylsulfonyl fluoride, and 1 mM DL-dithiothreitol) added with Protease Inhibitor Cocktail. These total protein extracts were assessed by Western blot using the experimental procedure described elsewhere [20]. Equal amounts of protein (ovary, 50  µ g; vagina, 50  µ g) were denatured in Laemmli's sample buffer, resolved through 10% SDS-polyacrylamide gels, and electrotransferred to nitrocellulose membranes (Bio-Rad Laboratories Headquarters).…”

“…This may be related to an increase in the extragonadal aromatization that could impair concurrent actions mediated by circulating androgens [20, 22]. Taking into account that pelvic floor tissues of some female mammals express aromatase [20, 23], it is reasonable to expect that the locally synthesized estrogens and androgens are also relevant for the morphology of pelvic neurons.…”

Hypothyroidism Reduces the Size of Ovarian Follicles and Promotes Hypertrophy of Periovarian Fat with Infiltration of Macrophages in Adult Rabbits

“…The expression of aromatase in the ovary was done by Western blot as reported elsewhere [18]. Portions (anterior, middle, and posterior) of right ovaries from each rabbit were used to get 50 mg of tissue and to obtain total protein extracts.…”