Submandibular and parotid salivary secretion after electrolytic lesioning of the brainstem nucleus parvocellularis in the rat

Abstract

The present study, in consonance with recent anatomical investigations, demonstrates that activation of the nucleus parvocellularis in the rat evokes a potent hypersecretory effect in the submandibular and sublingual (S-S) salivary glands. Furthermore, electrolytic lesioning of this region in conjunction with peripheral removal of the parotid glands is followed by an increase in the number of drinking responses in the presence of dry food. Such prandial drinking behavior is only observed after total impairment of salivation (i.e, removal of the S-S + parotid glands), thus suggesting that the parvocellularis lesion led to a marked deficit in S-S salivary secretion (Experiment 1). On the other hand, the activation of the nucleus parvocellularis was seen to have only a slight effect on parotid salivary secretion. Electrolytic lesions to this zone, when associated with peripheral removal of the S-S glands, failed to induce prandiality, suggesting that the parvocellularis nucleus exerted a low level of control over parotid salivary secretion (Experiment 2). These results are interpreted as functional proof of the relationship between the parvocellularis reticular formation and the superior salivatory nucleus in the secretion of S-S saliva.