Effects of naloxone, serotonin, and dopamine on reproduction of the freshwater crabBarytelphusa guerini

Abstract

Several investigators suggest a relationship between neurotransmitters, serotonin (also called 5-hydroxytryptamine, 5-HT), and dopamine (DA) in the regulation of growth and reproductive development of vertebrate species, rather than the invertebrate species. In this study, we evaluated the role of 5-HT and DA in reproductive development of an invertebrate species, the freshwater crab Barytelphusa guerini. We tested the effects of 5-HT both alone and combined, and also the effects of an opioid antagonist naloxone, on reproductive development of B. guerini in terms of testicular and ovarian developmental parameters. Injection of either 5-HT or naloxone alone significantly increased the ovarian index and the oocyte diameter in female crabs, and the testicular index and testicular follicular diameter in male crabs. In contrast, injection of DA inhibited all the reproductive measures in both sexes. Co-injection of 5-HT with DA exhibited no significant effects on the reproductive development in both sexes compared to the control treatments. These results suggest that 5-HT, DA, and exogenous naloxone may be involved in the regulation of gonad stimulating hormone (GSH) and/or gonad inhibiting hormone (GIH). These results also provide evidence that naloxone may regulate endogenous neurotransmitters and its downstream hormones, GSH and GIH.

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

“…In agreement with the present observations, dopamine injection in P. clarkii displayed low testicular index and acinar diameter values, fewer mature spermatozoa and poorly developed androgenic glands (Sarojini et al, 1994;. In U. pugilator and B. guerini, Sarojini et al (1993) and Prasad et al (2014) documented low values for testicular index and acinar diameter following dopamine treatment. Poljaroen et al (2011) and Siangcham et al (2013) reported significantly low testicular index, acinar diameter and germ cell proliferation and more number of immature spermatocytes in M. rosenbergii administered with dopamine.…”

“…A similar elevation in testicular index, acinar diameter, proportion of mature spermatozoa and active proliferation of spematogonial cells was observed in M. rosenbergii following serotonin administration (Poljaroen et al, 2011;Siangcham et al, 2013). Prasad et al (2014) observed a significant boost in testicular index and mean acinar diameter in a dose dependent manner in serotonin injected B. guerini. Treatment with leucine enkephalin, a stimulatory neurotransmitter, drastically enhanced the testicular index and mean acinar diameter values in the freshwater field crab Oziotelphusa senex senex (Reddy, 2003) and the eastern lubber grasshopper Romalea microptera (Kumar et al, 2013).…”

“…Siangcham et al (2013) studied the effects of 5-HT and DA on androgenic gland activity in M. rosenbergii. A significant enhancement and delay in testicular activity was observed by Prasad et al (2014) in Barytelphusa guerini following 5-HT and DA injections.…”

Potential spawn induction and suppression agents in CaribbeanAcropora cervicorniscorals of the Florida Keys

“…It may provide a cheap alternative to chemical grade serotonin. The opioid antagonist, naloxone hydrochloride dihydrate, was found to reliably induce reproductive development in the freshwater crab species, Barytelphusa guerini ( Prasad et al, 2014 ). Both these latter chemicals are believed to work by either up-regulating gonad stimulating hormone (GSH) or down-regulating gonad inhibiting hormone (GIH) ( Niaraki, Subramanian & Moghissi, 1982 ; Prasad et al, 2014 ; Van Bergeijk et al, 1986 ).…”

“…The opioid antagonist, naloxone hydrochloride dihydrate, was found to reliably induce reproductive development in the freshwater crab species, Barytelphusa guerini ( Prasad et al, 2014 ). Both these latter chemicals are believed to work by either up-regulating gonad stimulating hormone (GSH) or down-regulating gonad inhibiting hormone (GIH) ( Niaraki, Subramanian & Moghissi, 1982 ; Prasad et al, 2014 ; Van Bergeijk et al, 1986 ). Phosphate is a primary ingredient in many lawn fertilizer products and has been identified as a pollutant of many coastal environments, including the Florida Keys, through waste-water and storm-water runoff from lawns ( Corbett et al, 2000 ; Dillon et al, 2003 ; Lapointe, O’Connell & Garrett, 1990 ).…”