RESUMO
Parotid gland has a dual nerve supply: sympathetic and parasympathetic. They both activate salivary secretion. Parasympathetic stimulation results in copious watery secretion whereas sympathetic stimulation results in small amount of enzyme-rich secretion. The aim of the present study was to compare between the effect of three different drugs [alpha and beta adrenergic and cholinergic] on the ultrastructure of parotid acini in albino rats. Twenty eight adult male albino rats were used in this study. They were divided into four groups: group I [control group], group II [pilocarpine group], group III [noradrenaline group] and group IV [isoproterenol group]. Group II, III and IV were further subdivided according to the duration of treatment into subgroup A that received one single injection and subgroup B that received a daily injection for seven days. 1. Pilocarpine group showed wide intercellular canaliculi of parotid acini denoting the release of profuse watery secretion. 2. Isoproterenol group revealed degranulation of serous acinar cells denoting the release of enzyme-rich secretion. 3. Noreadrenaline group showed degenerative changes in the cytoplasmic organelles as well as the nuclei of serous acinar cells. Thus, noreadrenaline is not recommended to be used clinically as a salivary stimulant