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Effect of Pinealectomy, Eye Enucleation, and Melatonin Treatment on Ovarian Activity and Vitellogenin Levels in the Catfish Exposed to Short Photoperiod or Long Photoperiod
Author(s) -
Garg S.K.
Publication year - 1989
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1989.tb00658.x
Subject(s) - pinealectomy , melatonin , photoperiodism , biology , pineal gland , endocrinology , medicine , enucleation , reproduction , catfish , botany , ecology , fish <actinopterygii> , fishery , genetics
To investigate the relative importance of pineal, and eyes, and melatonin treatment on ovarian activity, catfish, Heteropneustes fossilis subjected to pinealectomy, eye nucleation, or both were exposed to short (LD 9:15) or long (LD 14:10) photoperiod during the different stages of the annual reproductive cycle. During the preparatory period, pinealectomy accelerated ovarian recrudescence under long photoperiod, but no effects of pinealectomy were observed under short photoperiod. Pineal has no influence on ovarian activity during the preplanning and spawning periods of the reproductive cycle. In the late postspawning period, ovarian recrudescence is accelerated after pinealectomy in catfish maintained under short photoperiod (LD 9:15 at 25°C). But under long photoperiod (LD 14:10 at 25°C), pinealectomy delayed ovarian recrudescence. An investigation into the role of the eyes revealed that eye enucleation nullifies the inhibitory effects of LD 9:15 and represses the stimulatory effects of LD 14:10. Combined surgery inhibited ovarian development under both the regimes. It is significant that pinealectomy and/or blinding neither counteracted nor delayed the post spawning ovarian regression. The findings suggest that the role of the pineal in catfish reproduction is variable and depends upon the photoperiod to which they are exposed as well as on the time of the year and the stage of the reproductive cycle. It is concluded that extra retinal and extra pineal photoreceptors also are involved in influencing seasonal reproduction. Further, no effects of melanoma treatment on ovarian activity or on vitellogenin levels during the preparatory or preplanning periods were observed, indicating that the pineal effects on gondola activity in catfish may not be mediated through the secretion of melatonin.