Physiological responses of freshwater giant prawn, Macrobrachium rosenbergii under stress

Biogenic amines are widely distr ibuted
in the neural system and ganglia of
crustaceans. They, act as neurotransmitters
and neuroregulator s, are involved
in regulating a wide spectrum of impor tant
physiological processes in organisms,
including glucose metabolism and
glycemic response, which is frequently
used as a biological indicator of the
physiological conditions.
The objectives of the present research
are aimed to clarify the modes and
pathways of the actions of norepinephr ine,
epinephr ine, dopamine and serotonin in
the glycemic responses of Macrobrachium
rosenbergii in vitro. The goal is approached
by incubation of the hepatopancreas tissue
with biogenic amine alone or with the
combination of biogenic amine and its
specific receptor antagonists, and the
responses were monitored by quantifying
the glucose content in the culture medium
at 2 hr intervals. The culture medium
and biogenic amines exper imented are
replenished at the same time. The results
revealed that all the biogenic amines
examined in this study, do enhance the
glucose release from the hepatopancreas
and muscular tissues. This suggests that
the hyperglycemic response is not
necessar ily mediated through the actions
of CHH, secreted and released from xorgan
sinus gland complex. In the
meantime, the hepatopancreas can be
considered to be more impor tant for the
source of energy supply, when the glucose
released at a specific dose is compared.
In addition, the pathways of the actions
of the biogenic amines is summarized as follows: the actions is mediated through a1
and b1 for norepinephr ine and epinephr ine,
and through D1 and 5-HT2 for dopamine
and 5-HT, respectively. The
pharmacological research strategies were
followed in this study, and the antagonists
employed were all developed in mammals.
The homology of the receptors of NE, E,
DA and 5-HT, and the affinity of
antagonists to var ious receptors between
the freshwater giant prawn and mammals
are still unknown and remained for
fur ther elucidation.