Effect of administration of neurotransmitters: Serotonin and dopamine on testicular maturation in the freshwater crab Travancoriana schirnerae Bott, 1969 (Crustacea: Gecarcinucidae)

The current investigation aimed at the effect of administration of the neurotransmitters, serotonin and dopamine, on testicular maturation in the freshwater crab Travancoriana schirnerae Bott, 1969 (Crustacea: Gecarcinucidae). Adult males in active, inactive and revival phases of spermatogenesis were injected with serotonin and dopamine in multiple doses and their dissected testes were submitted to histomorphological examinations. Though serotonin treatment during active phase showed increased values for testicular index, acinar diameter and proportion of mature spermatozoa, only the testicular index values differed statistically from that of controls. Serotonin administration during inactive phase caused an increase in testicular index and acinar diameter, reduction in intra and interacinar spaces and pycnosis of germ cells and detection of division stages. A notable increase in the testicular index, acinar diameter and fresh batches of spermatozoa was perceptible in crabs injected with serotonin during revival phase. In contrast, dopamine injection showed a decline in testicular activity irrespective of the phase of spermatogenesis, as evinced from low testicular index, acinar diameter, presence of small, irregularly shaped acini with indistinct acinar boundaries, reduction in the number of mature spermatozoa and absence of division stages. To conclude, the stimulatory neurotransmittant, serotonin can be used to induce testicular maturation in species of aquaculture potential.