Brain levels of 5-hydroxytryptamine and dopamine in Blattella germanica adult females during the first gonadotrophic cycle

Abstract

Brain levels of 5-hydroxytryptamine (5-HT) and dopamine (DA) were determined along the first gonadotrophic cycle of Blattella germanica adult females. High-performance liquid chromatography (HPLC) combined with electrochemical (for DA) or fluorimetric (for 5-HT) detection was used. 5-HT levels did not show significant fluctuations, whereas DA levels showed characteristic ontogenetic changes which can be related to various events during the gonadotrophic cycle. The profile of DA levels in the first half of the cycle suggest an amine accumulation until days 2-3 (beginning of vitellogenesis) and a sudden drop occurring on day 4 (significant increase of oocyte length). In the second half of the cycle, DA levels show a peak on day 5 (full vitellogenesis) followed by a decrease on day 6 (termination of oocyte maturation) and a progressive increase up to days 7 (chorionation, ovulation, oviposition, ootheca formation) and 8 (24h after the formation of the first ootheca). These results suggest the possible involvement of DA in these events of the gonadotrophic cycle.