Influence of fasting and isolation on biogenic amine levels in the nervous system of the male cockroach Blaberus craniifer Burm. (Dictyoptera, Blaberidae)

1. The effects of long-term starvation and isolation on biogenic amine contents of the central nervous system of the male cockroach Blaberus craniifer Burm. were investigated.

2. Levels of tryptophan, 5-hydroxytryptophan, 5-hydroxytryptamine, a 5-hydroxyindolacetic acid-like substance, N-acetyl-5-hydroxytryptamine, dopamine, N-acetyldopamine and octopamine were measured by HPLC with electrochemical detection in fasted-isolated and fed-crowded insects from day 0 (imaginal molt) to day 30.

3. Isolation and fasting resulted in general lower levels, except for serotoninergic pathway at day 10.

4. From these data, by comparison with the isolation effect registered in females: (i) it is hypothesized that fasting exerts an inhibitory influence; and (ii) it is speculated that this effect is convergent with that of the loss of mechanical feeding stimuli on neurosecretory cells, as described in other male cockroaches.