Chemical stress-induced changes in the biogenic amine levels of periplaneta americana L

Various biogenic amines, including octopamine (OA), dopamine, serotonin, their precursors, and metabolites, in the hemolymph and central nervous system of the American cockroach (Periplaneta americana L.) were detected electrochemically. OA was found in similar high relative abundances in the hemolymph and central nervous system of 2-butanone-treated cockroaches. The amount of OA was much higher than that of tyramine (TA) or synephrine (SN) in the hemolymph; OA, SN, and TA were found in almost equal amounts in the thoracic nerve cord, whereas in the brain, TA was at the highest level followed by OA and SN. Cockroaches were chemically stressed by topically applying representatives of pyrethroid, formamidine, organochlorine, organophosphorus, or carbamate insecticides. This treatment resulted in the elevation of OA, β-(3,4-dihydroxy-phenyl)alanine, norepinephrine (NE), tryptophan, and 3,4-dihydroxymandelic acid (DOMA) in the brain, whereas in the thoracic nerve cord, significant increases of OA, TA, epinine (EN), DOMA, epinephrine (E), 3,4-dihydroxyphenylacetic acid, and 5-hydroxytryptophan (5-HTP) were observed. TA, E, NE, tyrosine, DOMA, and 5-hydroxyindole-3-acetic acid (5-HIAA) were elevated in the hemolymph, respectively. TA, EN, dopamine (DA), E, 5-HIAA, and normetanephnne were depleted in the brain, NE was reduced in the thoracic nerve cord, and 5-HTP, EN, DA, and homovanilic acid were decreased in the hemolymph.