Kynurenine Pathway of Tryptophan Metabolism and Its Significance in Neurophysiology of Insects

摘要

The genetics and physiology of the kynurenine pathway of tryptophan metabolism (KPTM), whose end-products are shield pigments of insect eye, the ommochroms, are well studied (Linzen, 1974, and others). This paper summarizes the results of the 30-yearstudies of the neuroactivity of the KPTM product, the kynurenine, in drosophila (Drosophila melanogaster Meig.) and honey bee (Apis mellifera L.). A combination of genetic and pharmacological methods was used to manipulate the kynurenine level. The dataobtained allow one to classify kynurenines by their effect on the nervous system and behavior in the following way: (1) participation in the functional maturation of the nervous system during ontogenesis; (2) development of the stress response (Smirnov,1998); (3) participation in preserving the newly formed associations in the memory; (4) one of the mechanisms of neuronal and behavioral regulation, realized through changes in the functional state of the ionotropic and me-tabotropic receptors of L-glutamic acid. The studies clearly show the role of kynurenines in the functional maturation of the nervous system during ontogenesis and in regulation of its functions in adult insects. The role of KPTM, with its maximum activity during the metamorphosis, inthe neurogenesis per se was studied by Cerstiaens et al. (2002). The work of these and other authors (e.g., Chiow et al., 1998) confirms the significance of kynurenines in regulation of insect motility (Neobellieria bullata, Locusta migratoria). The conservatism of KPTM in insects and mammals is noteworthy.