The present investigation documents how endogenous levels of
5-HT and DA change in the ovaries and nervous system in M. rosenbergii
during the ovarian cycle. Variations in the concentration of
5-HT in the ovaries appear to be correlated with changes in brain
and thoracic ganglia throughout the four stages of the cycle. Specifically,
5-HT levels rose steadily in all three structures from ovarian
stage I to ovarian stage IV. In contrast, levels of DA in the brain,
thoracic ganglia, and ovaries were high in ovarian stages I and II,
and declined in ovarian stages III and IV. Thus, changes in DA concentration
in the brain, thoracic ganglia, and ovaries were essentially
opposite to those of 5-HT. This suggests that the two
transmitters may play opposite roles in regulating ovarian maturation.
Maximal DA levels occurred in stage I in the ovaries and in
stage II in the brain and thoracic ganglia. Thus, the relationship between
DA levels in the ovaries, brain and thoracic ganglia does not
appear to be as tightly correlated as for 5-HT. Changes in DA and 5-
HT levels in the abdominal ganglia during various stages of the
ovarian cycle were not statistically significant.