« Previous AbstractConditioned sexual arousal in a nonhuman primate    Next AbstractFunctional Characterization of a 28-Kilobase Catabolic Island from Pseudomonas sp. Strain M1 Involved in Biotransformation of beta-Myrcene and Related Plant-Derived Volatiles »

J Comp Physiol A

Title:		Causal connection between detoxification enzyme activity and consumption of a toxic plant compound
Author(s):		Snyder MJ; Glendinning JI;
Address:		"Department of Entomology, University of Arizona, Tucson 85721, USA"
Journal Title:		J Comp Physiol A
Year:		1996
Volume:		179
Issue:		2
Page Number:		255 - 261
DOI:		10.1007/BF00222792
ISSN/ISBN:
Abstract:		"Insect herbivores can increase their detoxification activities against a particular plant poison in response to prolonged ingestion of the same compound. For example, larval tobacco hornworms (Manduca sexta) experience a dramatic increase in cytochrome P450 activity against nicotine after ingesting nicotine. While it is generally assumed that this induction process permits increased consumption of toxic plant tissues, we are not aware of any direct experimental support for this assumption. Using a two-tiered approach, we examined the functional significance of P450 induction to M. sexta larvae ingesting a toxic but non-deterrent concentration of nicotine. First, we related the time-course of P450 induction in midgut microsomes to changes in nicotine consumption. When offered a nicotine diet, larvae failed to show a significant increase in consumption before 36 h, which was coincident with the time-course of the induction of midgut P450 activities against aldrin and nicotine. Second, we determined whether inhibiting the induced P450 activities affected nicotine consumption. We found that the increase in nicotine consumption following the induction of nicotine metabolism could be strongly inhibited by treatment with piperonyl butoxide, which by itself did not inhibit consumption. These results provide direct evidence for a causal connection between P450-mediated detoxification activity and consumption of a toxic plant compound"
Keywords:		Animals Cholinergic Agents/pharmacology Cytochrome P-450 Enzyme Inhibitors Cytochrome P-450 Enzyme System/*biosynthesis Diet Enzyme Induction/drug effects Enzyme Inhibitors/pharmacology Feeding Behavior/drug effects/*physiology Kinetics Larva Manduca/*met;
Notes:		"MedlineSnyder, M J Glendinning, J I eng DC00082/DC/NIDCD NIH HHS/ Research Support, U.S. Gov't, Non-P.H.S. Research Support, U.S. Gov't, P.H.S. Germany 1996/08/01 J Comp Physiol A. 1996 Aug; 179(2):255-61. doi: 10.1007/BF00222792"