Pharmacology of serotonin-induced salivary secretion in Periplaneta americana

J Insect Physiol. 2007 Aug;53(8):774-81. doi: 10.1016/j.jinsphys.2007.02.020. Epub 2007 Mar 18.

Abstract

The acinar salivary gland of the cockroach, Periplaneta americana, is innervated by dopaminergic and serotonergic nerve fibers. Stimulation of the glands by serotonin (5-hydroxytryptamine, 5-HT) results in the production of a protein-rich saliva, whereas stimulation by dopamine results in saliva that is protein-free. Thus, dopamine acts selectively on ion-transporting peripheral cells within the acini, and 5-HT acts on protein-producing central cells. We have investigated the pharmacology of the 5-HT-induced secretory activity of isolated salivary glands of P. americana by testing several 5-HT receptor agonists and antagonists. The effects of 5-HT can be mimicked by the non-selective 5-HT receptor agonist 5-methoxytryptamine. All tested agonists that display at least some receptor subtype specificity in mammals, i.e., 5-carboxamidotryptamine, (+/-)-8-OH-DPAT, (+/-)-DOI, and AS 19, were ineffective in stimulating salivary secretion. 5-HT-induced secretion can be blocked by the vertebrate 5-HT receptor antagonists methiothepin, cyproheptadine, and mianserin. Our pharmacological data indicate that the pharmacology of arthropod 5-HT receptors is remarkably different from that of their vertebrate counterparts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Periplaneta / drug effects*
  • Salivation / drug effects*
  • Serotonin / pharmacology*
  • Serotonin Antagonists / pharmacology*
  • Serotonin Receptor Agonists / pharmacology*

Substances

  • Serotonin Antagonists
  • Serotonin Receptor Agonists
  • Serotonin