Dopaminergic Regulation of Gonadotropin-II Secretion in Testosterone-treated Precocious Male and Immature Rainbow Trout Oncorhynchus mykiss

  • Kim, Dae-Jung (Taean Marine Hatchery, national Fisheries Research and Development Institute) ;
  • Aida, Katsumi (Department of Aquatic Bioscience, Graduate School of Agricultural and Life Science, The University of Tokyo)
  • Published : 2000.09.01

Abstract

The present work examined the role of gonadotropin-releasing hormone (GnRH) and dopaminergic drugs on the secretion of maturational gonadotropin (GTH II) in relation to testosterone m treatment. This study provides evidence that the plasma GTH II levels are increased by T treatment in precocious males, but not in the immature animal. In addition, GnRH analogue (GnRHa) alone significantly increased the plasma GTH II secretion in immature rainbow trout treated with T, as well as in T-treated and T-untreated precocious males. However, injection with either dopamine (DA) or domperidone (DOM; DA D2 receptor antagonist) alone did not alter the basal plasma GTH 11 secretion in all experimental groups. The secretion of GTH II in the T-treated precocious males was remarkably influenced by GnRHa or combination of dopaminergic drugs. Notably, the effects of dopaminergic drugs on GnRHa-induced GTH II secretion w8s prolonged by T in precocious males. In T-treated immature animals, GnRHa-induced GTH II secretion was Increased only by a dose DOM (10$\mu$g/g body n) but not by higher dose DOM (100$\mu$/g body wt). In the T-untreated immature rainbow trout, however, plasma GTH 11 secretion was not influenced by the same treatments. Therefore, these results indicate that DA may be acting indirectly by blocking the effect of GnRH on GTH II secretion in vivo. T may act to modulate the relative contribution by the stimulatory (GnRH) and inhibitory (DA) neuroendocrine factors, which would ultimately determine the pattern of GTH II secretion.

Keywords

References

  1. Amano M, Hyodo S, Urano A, Okumoto N, Kitamura S, Ikuda K, Suzuki Y, and Aida K (1994) Activation of salmon gonadotropin-releasing hormone synthesis by 17${\alpha}$-methyltestosterone administration in yearing masu salmon, Oncorhynchus masu. Gen Comp Endocrinol 95: 374-380 https://doi.org/10.1006/gcen.1994.1136
  2. Billard R, Reinaud P, Hollebecq MG, and Breton B (1984) Advancement and synchronisation of spawning in Salmo gairdneri and S. trutta following administration of LHRH combined or not with pimozide. Aquculture 43: 57-66 https://doi.org/10.1016/0044-8486(84)90009-7
  3. Chang JP and Peter RE (1983) Effects of dopamine on gonadotropin release in female goldfish, Carassius auratus. Neuroendocrinology 36: 351-357
  4. Crim LW and Evans DM (1983) Influence of testosterone and/or luteinizing hormone-releasing hormone analogue on precocious sexual development in the juvenile rainbow trout. Biol Reprod 29: 137-142 https://doi.org/10.1095/biolreprod29.1.137
  5. Crim LW, Nestor JJJr, and Wilson CE (1988) Studies of the biological activity of LHRH analogs in the rainbow trout, landlocked salmon, and winter flounder. Gen Comp Endocrinol 71: 372-382 https://doi.org/10.1016/0016-6480(88)90265-1
  6. Copeland PA and Thomas P (1989) Control of gonadotropin release in the Atlantic croaker (Micropogonias undulatus): Evidence for lack of dopaminergic inhibition. Gen Comp Endocrinol 74: 474-483 https://doi.org/10.1016/S0016-6480(89)80045-0
  7. Dufour S, Lopez E, Le Menn F, Le Belle N, Baloche S, and Fontaine YA (1984) Stimulation of gonadotropin release and of ovarian development by the administration of a gonadoIiberin agonist and of dopamine antagonists in female silver eel pretreated with estradiol. Gen Comp Endocrinol 70: 20-30 https://doi.org/10.1016/0016-6480(88)90090-1
  8. De Leeuw R, Resink JW, Rooyakkers EJM, and Goos HJTh (1985) Pimozide modulates the luteinizing hormone-releasing hormone effect on gonadotrophin release in the African catfish, Clarias lazera. Gen Comp Endocrinol 58: 120-127 https://doi.org/10.1016/0016-6480(85)90144-3
  9. De Leeuw R, Goos HJTh, and Oordt PGWJ (1987) The regulation of gonadotropin release by neurohormones and gonadal steroids in the African catfish, Clarias gariepinus. Aquaculture 63: 43-58. https://doi.org/10.1016/0044-8486(87)90060-3
  10. De Leeuw R, Van't Veer C, Goos HJTh, and Oordt PGWJ (1988) The dopaminergic regulation of gonadotropin-releasing hormone receptor binding in the pituitary of the African catfish, Clarias gariepinus. Gen Comp Endocrinol 72: 408-415
  11. De Leeuw R, Habibi HR, Nahorniak CS, and Peter RE (1989) Dopaminergic regulation of pituitary gonadotropin-releasing hormone receptor activity in the goldfish, Carassius auratus. J Endocrinol 121: 239-247
  12. Gielen JT and Goos HJT (1984) The brain-pituitary-gonadal axis in the rainbow trout, Salmo gairdneri. III. Absence of an inhibiting action of testosterone on gonadotropin release in juveniles. Gen Comp Endocrinol 56: 457-465 https://doi.org/10.1016/0016-6480(84)90088-1
  13. Kim DJ, Amano M, Kobayashi M, Suzuki Y, and Aida K (1995) Dopaminergic regulation of the release of gonadotropin from dispersed pituitary cells of testosterone-treated immature rainbow trout, Oncorhynchus mykiss. In: Proceedings of the Japan Society for Comparative Endocrinology, Shizuoka, Japan, p 60
  14. Kobayashi M, Aida K, Sakai H, Kaneko T, Asahina K, Hanyu I, and Ishii S (1987) Radioimmunoassay for salmon gonadotropin. Nippon Suisan Gakkaishi 53: 995-1003
  15. Linard B, Bennani S, and Saligaut C (1995) Involvement of estradiol in a catecholamine inhibitory tone of gonadotropin release in the rainbow trout, Oncorhynchus mykiss. Gen Comp Endocrinol 99: 192-196 https://doi.org/10.1006/gcen.1995.1101
  16. Omeljaniuk RJ, Habibi HR, and Peter RE (1989) Alterations in pituitary GnRH and dopamine receptors associated with the seasonal variation and regulation of gonadotropin release in the goldfish (Carassius auratus). Gen Comp Endocrinol 74: 392-399 https://doi.org/10.1016/S0016-6480(89)80036-X
  17. Omeljaniuk RJ (1995) Specific [$^3H$] spiperone binding sites in the pituitary of rainbow trout (Oncorhynchus mykiss) and goldfish (Carassius auratus). Can J Physiol Pharmacol 73: 585-593
  18. Peter RE, Chang JP, Nahorniak CS, Omeljaniuk RJ, Sokolowska M, Shih SH, and Billard R (1986) Interactions of catecholamines and GnRH in regulation of gonadotropin secretion in teleost fish. Recent Progr Horm Res 42: 513-548
  19. Peter RE, Trudeau VL, and Sioley BD (1991) Brain regulation of reproduction in teleosts. Bull Inst Zool Acad Sinica Monogr 16: 89-118
  20. Saligaut C, Salbert G, Bailhache T, Bennani S, and Jego P (1992) Serotonin and dopamine turnover in the female rainbow trout (Oncorhynchus mykiss) brain and pituitary: changes during the annual reproductive cycle. Gen Comp Endocrinol 85: 261-268 https://doi.org/10.1016/0016-6480(92)90010-H
  21. Saligaut C, Linard B, Mananos EL, Kah 0, Breton B, and Govoroun M (1998) Release of pituitary gonadotropins GtH I and GtH II in the rainbow trout (Oncorhynchus mykiss): Modulation by estradiol and catecholamines. Gen Comp Endocrinol 109: 302-309 https://doi.org/10.1006/gcen.1997.7033
  22. Saligaut C, Linard B, Breton B, Anglade I, Bailhache T, Kah 0, and Jego P (1999) Brain aminergic systems in salmonids and other teleosts in relation to steroid feedback and gonadotropin release. Aquaculture 177: 13-20 https://doi.org/10.1016/S0044-8486(99)00065-4
  23. Senthilkumaran B and Joy KP (1996) Effects of administration of some monoamine-synthesis blockers and precursors on ovariectomy-induced rise in plasma gonadotropin of the catfish, Heteropneustes fossilis. Gen Comp Endocrinol 101: 220-226 https://doi.org/10.1006/gcen.1996.0024
  24. Sokolowska M, Peter RE, Nahorniak CS, and Chang JP (1985) Seasonal effects of pimozide and des $Gly^{10}[D-Ala^6]$ LHRH ethylamide on gonadotrophin secretion in goldfish. Gen Comp Endocrinol 57: 472-479 https://doi.org/10.1016/0016-6480(85)90230-8
  25. Trudeau VL, Sioley BD, Wong AOL, and Peter RE (1993) Interactions of gonadal steroids with brain dopamine and gonadotropin-releasing hormone in the control of gonadotropin-II secretion in the goldfish. Gen Comp Endocrinol 89: 39-50 https://doi.org/10.1006/gcen.1993.1007
  26. Van der Kraak G, Donaldson EM, and Chang JP (1986) Dopamine involvement in the regulation of gonadotropin secretion in coho salmon. Can J Zool 64: 1245-1248