Pineal‐gonadal relationship in the teleost Channa punctatus (Bloch): Evidence for possible involvement of hypothalamic serotonergic system
- 1 August 1991
- journal article
- research article
- Published by Wiley in Journal of Pineal Research
- Vol. 11 (1), 12-22
- https://doi.org/10.1111/j.1600-079x.1991.tb00821.x
Abstract
In Channa punctatus, pinealectomy results in an accelerated growth (stimulatory effect) of the ovary in preparatory phase (March), but had no significant effect in prespawning (May-June) or postspawning (September) phases. Administration of melatonin (25 micrograms/fish or 0.4 mg/kg BW at 2-day intervals for 30 days) inhibits the stimulatory effect of a long photoperiod and high temperature (16L:8D; 22 +/- 1 degree C) on the ovary in the early preparatory phase (February). In the late preparatory phase (April), the administration of both melatonin (0.5 mg/kg BW at 2-day intervals) and parachlorophenylalanine (pCPA, a serotonin synthesis blocker; 100 mg/kg BW at 3-day intervals) for 30 days inhibits ovarian activity in comparison to that of the saline-treated control group. In the dose-response study, greater than or equal to 0.5 mg/kg BW of melatonin induced a significant increase in hypothalamic 5-HT content and greater than or equal to 10 mg/kg BW of pCPA decreased it significantly. In the time-course study, melatonin (2.0 mg/kg BW) elevates the 5-HT content significantly after an hr of the injection and maintained it up to 48 hrs. The administration of pCPA (200 mg/kg BW) had significantly inhibited the 5-HT content which was sustained for 72 hr. In another study, a single injection of melatonin (0.5 mg/kg BW) increased the 5-HT content significantly. A single injection of pCPA (100 mg/kg BW) decreased significantly both the content and activity of 5-HT. It is inferred that hypothalamic 5-HT may play a central role in photosexual mechanisms and mediate long photoperiodic effects on neuroendocrine-reproductive axis.This publication has 30 references indexed in Scilit:
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