Enhanced expression of sodium hydrogen exchanger (NHE)-1, 2 and 4 in the uteri of rat model for post-menopause under phytoestrogen genistein influence

The Balance of [Formula: see text] Secretion vs. Reabsorption in the Endometrial Epithelium Regulates Uterine Fluid pH

Uterine fluid contains a high concentration of HCO3- which plays an essential role in sperm capacitation and fertilization. In addition, the HCO3- concentration in uterine fluid changes periodically during the estrous cycle. It is well-known that the endometrial epithelium contains machineries involving the apical SLC26 family anion exchangers for secreting HCO3- into the uterine fluid. In the present study, we find for the first time that the electroneutral Na⁺/HCO3- cotransporter NBCn1 is expressed at the apical membrane of the endometrial epithelium. The protein abundance of the apical NBCn1 and that of the apical SLC26A4 and SLC26A6 are reciprocally regulated during the estrous cycle in the uterus. NBCn1 is most abundant at diestrus, whereas SLC26A4/A6 are most abundant at proestrus/estrus. In the ovariectomized mice, the expression of uterine NBCn1 is inhibited by β-estradiol, but stimulated by progesterone, whereas that of uterine SLC26A4/A6 is stimulated by β-estradiol. In vivo perfusion studies show that the endometrial epithelium is capable of both secreting and reabsorbing HCO3-. Moreover, the activity for HCO3- secretion by the endometrial epithelium is significantly higher at estrus than it is at diestrus. The opposite is true for HCO3- reabsorption. We conclude that the endometrial epithelium simultaneously contains the activity for HCO3- secretion involving the apical SLC26A4/A6 and the activity for HCO3- reabsorption involving the apical NBCn1, and that the acid-base homeostasis in the uterine fluid is regulated by the finely-tuned balance of the two activities.

Genistein protects hippocampal neurons against injury by regulating calcium/calmodulin dependent protein kinase IV protein levels in Alzheimer's disease model rats

Genistein has a neuroprotective effect in Alzheimer's disease, but its mechanism of action needs further clarification. Accumulating evidence suggests that excessive phosphorylation of tau protein causes production of neurofibrillary tangles, which is one of the main pathological characteristics of Alzheimer's disease, and tau protein can be phosphorylated by calcium/calmodulin dependent protein kinase IV (CAMK4). After 7 days of pre-administration of genistein (90 mg/kg), an Alzheimer's disease rat model was established using an intraperitoneal injection of D-galactose combined with an intracerebral injection of amyloid-β peptide (25-35). The rat was then continuously administered genistein (90 mg/kg) for 42 days. The Morris water maze test, western blotting and hematoxylin-eosin staining results showed that genistein significantly decreased the escape latency and increased the number of times crossing the platform, reduced p-tau, CALM, CAMKK1 and p-CAMK4 protein levels in the hippocampus, and alleviated hippocampal neuron damage. These findings indicate that genistein may play a neuroprotective role in Alzheimer's disease through regulating CAMK4 to modulate tau hyperphosphorylation.

Combinatorial effect of genistein and female sex-steroids on uterine fluid volume and secretion rate and aquaporin (AQP)-1, 2, 5, and 7 expression in the uterus in rats

We hypothesized that genistein can interfere with the regulation of uterine fluid volume, secretion rate and expression of aquaporin in the uterus by female sex-steroids, i.e., estrogen and progesterone. Therefore, the aims of this study were to investigate changes in these parameters in the presence of genistein and female sex-steroids.

METHODS

Female Sprague-Dawley rats were ovariectomized and received 3-days estradiol-17β benzoate (E2) plus genistein (25, 50, or 100 mg kg^-1  day^-1 ) or 3-days E2 followed by 3-days E2 plus progesterone with genistein (25, 50, or 100 mg kg^-1  day^-1 ). A day after last treatment, uterine fluid secretion rate was determined by in vivo uterine perfusion with rats under anesthesia. Animals were sacrificed and uteri were harvested and subjected for histological analyses. Luminal/outer uterine circumference was determined and distribution of AQP-1, 2, 5, and 7 in endometrium was visualized by immunofluorescence. Expression of AQP-1, 2, 5, and 7 proteins and mRNAs were determined by Western blotting and Real-time PCR respectively.

RESULTS

Combined treatment of E2 with high dose genistein (50 and 100 mg kg^-1  day^-1 ) resulted in significant decrease in uterine fluid volume, secretion rate and expression of AQP-1, 2, 5, and 7 proteins and mRNAs in uterus (p < 0.05). No significant changes in these parameters were observed when 25 mg kg^-1  day^-1 genistein was given with E2 or when genistein was given with E2 followed by E2 plus progesterone Conclusions: Decreased in uterine fluid volume, secretion rate and AQP-1, 2, 5, and 7 expression in the uterus by high dose genistein in the presence of E2 could potentially affect female fertility. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 832-844, 2017.