Salivatory neurons in the brainstem nucleus parvocellularis of the rat: effects of electrolytic lesions.

ABSTRACT

This study was based on several recent anatomical studies suggesting that the superior salivatory nucleus is located within the area parvocellularis of the brainstem reticular formation. The aforementioned zone was lesioned in order to observe the alterations produced in salivary secretion. Electrolytic lesion of the area parvocellularis was followed by salivary hypersecretion as an immediate and transitory effect of the stimulatory capacity of the electrolytic lesioning method. Some days later the animals presented a markedly impaired salivary secretion as shown by the appearance of inefficient feeding behavior and the development of a prandial drinking pattern. The prandial behavior, which was characterized by numerous drinking episodes during dry food intake, was reversed when wet food was offered, suggesting a true deficit in salivary secretion caused by the parvocellularis lesion. Following the administration of pilocarpine, the submandibular and sublingual salivary glands of experimental animals showed an increased capacity for response (postsynaptic supersensitivity) in comparison to the control group.