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Title: ANGIOTENSIN II AND ANGIOTENSIN CONVERTING ENZYME AS CANDIDATE COMPOUNDS MODULATING THE EFFECTS OF TESTIS ECDYSIOTROPIN IN TESTES OF THE GYPSY MOTH,LYMANTRIA DISPAR

Author
item Loeb, Marcia
item DELOOF, ARNOLD - U OF LEUVEN, BELGIUM

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: If scientists could inhibit the maturation of adult insects, a great advance in insect control could be accomplished. However, the physiology of insect sexual development is not yet well understood. We previously showed that a peptide from the brains of male moth pupae, Testis Ecdysiotropin, induces testes to synthesize the hormone, ecdysteroid, and thus initiate maturation of the male genital tract. In this paper we show that a peptide similar to Angiotensin II, a mammalian hormone, as well as an enzyme known in mammals, Angiotensin Converting Enzyme, which acts on an Angiotensin II precursor, are active in insect testes. They inhibit the effects of Testis Ecdysiotropin in the testes, probably by inducing the production of the second messenger, cyclic AMP. This information can be used by scientists attempting to design molecules to specifically inhibit insect reproductive capabilities.

Technical Abstract: Heliothis virescens and Lymantria dispar testes synthesize immunodetectable ecdysteroid in vitro in response to the brain peptide, Testis Ecdysiotropin (TE), which elicits its action primarily via a cascade involving G(i) protein, diacyl glycerol and phosphokinase C. However, a component of TE activation also involves the opposite cascade, G(s) protein, cAMP and phosphokinase A. cAMP acts as an inhibitor, or modulator, of TE action when both compounds are added to the testis incubation medium. In this work, we found that bovine angiotensin II and bovine angiotensin converting enzyme act like cAMP, in that they induce synthesis of immunodetectable ecdysteroid by larval and pupal testes in vitro, but are antagonistic to TE when co-incubated together. Angiotensin II induces synthesis of cAMP by pupal testes in vitro. Therefore, angiotensin II and angiotensin converting enzyme are good candidates for the peptides responsible for the cAMP cascade, and as modulators of TE action in Lepidopteran testes. Saralasin, an analog of angiotensin II that blocks A(1) receptors to angiotensin II in mammalian steroid synthesizing tissues, was not inhibitory to AII action; it behaved like angiotensin II in inducing ecdysteroid secretion when incubated with L. dispar testes, with ecdysteroidogenic effects additive to either angiotensin or angiotensin converting enzyme. It inhibited ecdysteroid synthesis when combined with TE. The receptors for the insect form of angiotensin on Lepidopteran testis cells are probably different from those in mammals.