On the receptors involved in the nervous control of salivary secretion by Nauphoeta cinerea Olivier.

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Abstract
The isolated salivary glands of N. cinerea produce fluid secretion in response to nerve stimulation or bath applications of dopamine, noradrenaline [norepinephrine], adrenaline [epinephrine] and 5-HT [5-hydroxytryptamine]. These catecholamines, of which dopamine is the most potent, evoked maximal responses matching that of nerve stimulation whereas 5-HT was less effective. The receptors combining with 5-HT could be distinguished from those for the catecholamines and the transmitter at this salivary neuroglandular junction. The results of experiments where glands were stimulated by dopamine in the presence of noradrenaline or adrenaline suggested that there are receptors with specific binding sites for dopamine. The effects of several antagonists (Ginsborg et al., 1976) of the hyperpolarizing responses from acinar cells to nerve stimulation and these agonists were examined. Phentolamine reversibly suppressed the secretory responses to these stimuli whereas methysergide had no effect and ergometrine elicited fluid secretion in a dose-dependent manner.