Nitric oxide as putative second messenger in nerve-induced cervical gland secretion in the guinea-pig

Abstract

Uterine cervical secretory cells receive a sympathetic cholinergic secretomotor innervation. It has been suggested that glandular nitric oxide (NO) production is a prerequisite for muscarinic-induced carbohydrate secretion in the endometrium and the seminal vesicle. A similar pattern for nerve-induced carbohydrate secretion in the cervix could be assumed. Nitric oxide synthase (NOS) activity was evaluated via formation of L-citrulline from L-arginine. The NADPH-diaphorase nitroblue technique was used for histochemical investigation. The cervix with the adjacent hypogastric nerve was placed in an isolated organ bath and the secretion was evaluated as an amount of carbohydrate. A calcium-dependent formation of citrulline was found in the cervix indicating NO formation. Strong NADPH-staining cells were found in the glandular ducts and in the glandular linings of the cervix. Stimulation of the hypogastric nerve induced carbohydrate secretion, which was inhibited by N-nitro-L-arginine methyl ester (L-NAME). D-NAME did not affect the secretory response. Carbachol and the NO donor glyceryl trinitrate (GTN) induced carbohydrate secretion in the cervical glands. No synergistic effect was noted probably due to an all-or-none type of secretion. N-nitro-L-arginine (L-NNA) and L-NAME inhibited carbachol-induced secretion. The results suggest that glandular NO production is a prerequisite for the autonomic nervous modulation of cervical secretion in the guinea-pig. This could have implications regarding fertility and fecundity.