a b s t r a c tDopamine (DA), octop

a b s t r a c t
Dopamine (DA), octopamine (OA) and serotonin (5-HT) are the key neurotransmitters that control gonadal
development in decapod crustaceans. 5-HT stimulates, while DA and OA delay gonadal development in
Macrobrachium rosenbergii. In the present study,we have further investigated the distribution patterns of
DA and OA in the central nervous system (CNS) and ovary during various stages of the ovarian maturation
cycle of this giant freshwater prawn. DA- and OA-immunoreactive neurons and fibers were distributed
extensively in several regions of the brain, subesophageal ganglion (SEG), thoracic ganglia and abdominal
ganglia. In the brain, the two neurotransmitterswere present in neurons of clusters 6, 7, 11, 17, and nearby
neuropil regions. In the SEG, thoracic ganglia and abdominal ganglia, immunoreactive neurons and fibers
were found along the midline and in several neuronal clusters around each neuropil region. Staining for
DA and OA was more intense in the thoracic ganglia than in other parts of the CNS. In the ovary, DAand
OA-immunoreactivities were present at high intensity in early oocytes. The presence of DA- and OAimmunoreactivities
in neural ganglia as well as ovary suggests that DA and OA may also be involved in
the reproductive process, particularly ovarian development and differentiation of oocytes in this species.