Influence of parasympathetic non-adrenergic, non-cholinergic mechanisms on [3H]thymidine uptake in rat parotid salivary glands in response to mastication following upon a liquid regimen

A role for parasympathetic non-adrenergic, non-cholinergic (NANC) mechanisms in parotid gland cell hyperplasia in response to mastication was investigated. Following a liquid regimen for 1 week, aiming at glandular inactivity, rats were offered hard chow for 2 h to throw their parotid glands into secretory activity. In response to the increasing demands, [3H]thymidine incorporation into the trichloroacetic acid-insoluble material increased by 76% in normally innervated glands, while there was no increase in glands parasympathetically denervated in advance. In innervated glands of rats pretreated with atropine and α- and β-adrenoceptor blockers the increase was 46%. The results suggest a potential contribution of parasympathetic NANC mechanisms to the mitotic response of the parotid gland under natural feeding conditions.