Studies on the biochemical mechanisms of anorexia caused by formamidine pesticides in the American cockroach, Periplaneta americana L
1991
Ismail, S.M.M. | Matsumura, F.
Chlordimeform (CDM), a formamidine pesticide, causes intense anorexia in the American cockroach, Periplaneta americana L. at doses as low as 1 to 5 microgram/insect. We have studied the effect of this compound on the levels of mono- and disaccharide sugars in the hemolymph and found that such a phenomenon is accompanied by an increase in glucose and a simultaneous decrease in trehalose level. The combined level of glucose and trehalose remained relatively constant during the test period of 5 hr. An in vitro study has shown that trehalase activity in the thoracic muscles increased as a result of in vivo administration of CDM. The same phenomenon could be reproduced in vitro using N-demethylchlordimeform (DCDM) in place of CDM. These phenomena are very similar to those produced by octopamine (OA) both in vivo, and in vitro. Phentolamine (PA) antagonized such actions of OA and DCDM in the thoracic muscles. Furthermore, both DCDM and OA could elevate cAMP levels in vitro in muscle homogenate preparations. These results support the notion that CDM, after metabolic activation to the N-demethyl and N,N-didemethyl forms in vivo, acts on the OA receptor causing activation of the cAMP-mediated response system. The result of this activation is an increase in trehalase activity in the thoracic muscles which leads to the conversion of trehalose to glucose. The resulting increase in the hemolymph glucose is the likely biochemical cause of anorexia in this species.
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