The consistency of the cervical mucus changes with the reproductive cycle, which we hypothesized involved changing levels of cystic fibrosis transmembrane regulator (CFTR), adenylate cyclase (AC), and cyclic adenosine mono-phosphate (cAMP). We therefore measured the abundance of each in the rat cervix under estrogen and progesterone influence to determine if the activity of these components could explain the changes in the consistency of cervical mucus. Ovariectomised adult female rats were treated with three days of either estrogen (1 μg/kg/day) or progesterone (20 mg/kg/day), or three days of estrogen followed by two days of either vehicle or progesterone or estrogen plus progesterone. In some groups, mifepristone (7 mg/kg/day) was concurrently given with progesterone. Animals were then sacrificed, and the cervix was harvested for protein and mRNA expression analyses by Western blot and real-time PCR, respectively. The distribution of proteins was investigated by immunohistochemistry, and levels of cAMP were determined by enzyme-linked immunosorbent assay (ELISA). Cftr mRNA, AC protein, and cAMP levels in cervical homogenates as well as the tissue distribution of CFTR and AC in endocervical epithelia were highest under estrogen influence; the opposite pattern was seen under progesterone influence. Cervical lumen circumference was highest under estrogen and lowest under progesterone. The effects of progesterone were antagonized by mifepristone. Therefore, increased abundance of CFTR, AC, and cAMP under estrogen influence could account for the increased fluid accumulation within the cervical lumen, which would contribute to lower cervical mucus consistency, whereas progesterone reverses this effect at the molecular and organ level.
Absence of physiological concentrations of extracellular Ca2+ in the Krebs-Henseleit incubation buffer did not affect the ability of 10 nM glucagon (< 5%) to increase hepatocyte intracellular cyclic AMP concentrations, but severely ablated (by approximately 70%) the ability of 10 nM insulin to decrease these elevated concentrations. Cyclic AMP metabolism is determined by production by adenylate cyclase and degradation by cyclic AMP phosphodiesterase (PDE). In the absence of added extracellular Ca2+ (2.5 mM), insulin's ability to activate PDE activity was selectively compromised, showing a failure of insulin to activate two of the three insulin-stimulated activities, namely the 'dense-vesicle' and peripheral plasma-membrane (PPM) PDEs. In the absence of added Ca2+, insulin's ability to inhibit adenylate cyclase activity in intact hepatocytes was decreased dramatically. Vasopressin and adrenaline (+ propranolol) failed to elicit the activation of either the 'dense-vesicle' or the PPM-PDEs. The presence of physiological concentrations of extracellular Ca2+ in the incubation medium is shown to be important for the appropriate generation of insulin's actions on cyclic AMP metabolism.
Secretions of chloride (Cl(-))- and bicarbonate (HCO3(-))-rich fluid by the seminal vesicles could involve cystic fibrosis transmembrane regulator (CFTR), which activity can be stimulated by cAMP generated from the reaction involving adenylate cyclase (AC). In this study, we investigated levels of CFTR, AC, and cAMP in the seminal vesicles under testosterone influence. Orchidectomized adult male rats received 7-day treatment with 125 or 250 μg/kg/day of testosterone with or without flutamide or finasteride. At the end of the treatment, animals were sacrificed and seminal vesicles were harvested for analyses of CFTR and AC protein expression level by Western blotting. Distribution of CFTR and AC in seminal vesicles was observed by immunohistochemistry. Levels of cAMP and dihydrotestosterone in seminal vesicle homogenates were measured by ELISA. Cystic fibrosis transmembrane regulator, AC, and cAMP levels increased with increasing doses of testosterone (P
BACKGROUND AND AIMS OF THE WORK: Nitric oxide (NO) has been reported to enhance the production of cAMP by hydroxyapatite (HA)-induced a human osteoblast cell line (HOS cells). The aim of the present study was to test the hypothesis that exogenous NO may up-regulate the proliferation of hydroxyapatite (HA)-induced HOS cells via the cyclic-AMP-protein kinase A (PKA) pathway.