Physiological involvement of
DA in ovarian development of the freshwater giant prawn, Macrobrachium
rosenbergii
Y.N. Chen, H.F. Fan, S.L. Hsieh, C.M. Kuo-2003
Aquaculture: 288(1-4): 383-395
Abstract:
Biogenic amines such as dopamine (DA) and serotonin
(5-hydroxytryptamine, 5-HT) are able to affect numerous physiological
processes in crustaceans through their actions as neuroregulators. Both DA
and serotonin have been shown to be involved in the synthesis and release of
neurohormones such as crustacean hyperglycemic hormone (CHH),
vitellogenesis-inhibiting hormone (VIH), molt-inhibiting hormone (MIH) and
those related to pigmentation which in turn subsequently influence
homeostasis and homeokinesis. The effect of DA and 5-HT on the ovarian
development of the freshwater giant prawn, Macrobrachium rosenbergii,
as well as the pathway of these actions is presented in this paper.
During a 20-day experimental period, hemolymph was
collected from both intact and bilaterally eyestalk-ablated prawns 2 days
after each administration of DA and 5-HT which was injected into the prawns
on every fourth day. The vitellogenin concentration in the hemolymph was
then quantified using ELISA technique. The results show that DA depressed
vitellogenin synthesis while 5-HT enhanced the process. When DA was injected
with selective receptor antagonists, SCH23390, a DA D1 receptor
antagonist, was able to suppress DA's effect on vitellogenin synthesis while
domperidone, a DA D2 receptor antagonist, had no apparent effect,
suggesting that the actions of DA are primarily channeled through D1
receptor.
Given that DA is able to inhibit vitellogenin
synthesis in eyestalk-ablated prawns in a similar manner as in intact
prawns, it is clear that the inhibitory action of DA is at the thoracic
ganglia through inhibition of vitellogenesis-stimulating hormone (VSH)
release, but not at the eyestalk level through stimulation of VIH release
from the X organ–sinus gland complex.
(Department of Aquaculture, National Penghu Institute
of Technology, Makung, Penghu 880, Taiwan, e-mail of C.M. Kuo: cmkuo@gate.sinica.edu.tw)