Joy K P, Agha A K
Department of Zoology, Banaras Hindu University, Varanasi, India.
J Pineal Res. 1991 Mar;10(2):65-70. doi: 10.1111/j.1600-079x.1991.tb00012.x.
In Heteropneustes fossilis, effects of intraperitoneal administration (25 micrograms/fish, alternate days for a month 1 hr before the onset of dark phase) of melatonin (MEL) and 5-methoxytryptophol (5-MTL) on ovarian activity were investigated during different seasons of the annual reproductive cycle under natural photothermal conditions. The gonadosomatic index (GSI) had decreased significantly by MEL during preparatory and prespawning seasons, and by 5-MTL in all but the spawning season. Both MEL and 5-MTL administrations arrested vitellogenesis during the gonadal recrudescence phase. As a result, stage I previtellogenic oocytes showed a significant increase in the MEL group in the preparatory and prespawning seasons, and in the 5-MTL group only in the prespawning season. Almost the same trend was noticed in the percentage distribution of stage 2 and 3 oocytes. The percentage distribution of stage 4 postvitellogenic oocytes decreased significantly during the preparatory and prespawning seasons, but not in the spawning season. The indole treatment resulted in a highly significant increase in the percentage distribution of atretic oocytes during prespawning, spawning, and post-spawning phases. Total protein content of the ovary was significantly lower in all seasons after MEL treatment, and only in the preparatory and prespawning seasons following 5-MTL treatment. The ovarian glycogen level was significantly lower in the preparatory and prespawning seasons (MEL group), and in the 5-MTL group only in the prespawning phase. Ascorbic acid level was inhibited by the indole treatment in all seasons except in the 5-MTL group during the post-spawning season. The results show that both MEL and 5-MTL are effective in inhibiting ovarian vitellogenesis and inducing atresia in the catfish.
在印度胡鲶中，研究了在自然光热条件下，于年度繁殖周期的不同季节，腹腔注射褪黑素（MEL）和5-甲氧基色醇（5-MTL）（25微克/鱼，每隔一天注射一次，持续一个月，在黑暗期开始前1小时注射）对卵巢活动的影响。在准备期和产卵前期，MEL使性腺指数（GSI）显著降低；在除产卵季节外的所有季节，5-MTL使性腺指数显著降低。在性腺复苏期，MEL和5-MTL的注射均抑制了卵黄发生。结果，在准备期和产卵前期，I期卵黄生成前的卵母细胞在MEL组中显著增加，而在5-MTL组中仅在产卵前期显著增加。在2期和3期卵母细胞的百分比分布上也观察到了几乎相同的趋势。在准备期和产卵前期，4期卵黄生成后的卵母细胞百分比分布显著下降，但在产卵季节没有下降。吲哚处理导致在产卵前、产卵和产卵后阶段，闭锁卵母细胞的百分比分布显著增加。MEL处理后，卵巢总蛋白含量在所有季节均显著降低，5-MTL处理后仅在准备期和产卵前期显著降低。在准备期和产卵前期（MEL组），卵巢糖原水平显著降低，5-MTL组仅在产卵前期显著降低。除了在产卵后季节5-MTL组外，在所有季节中，吲哚处理均抑制了抗坏血酸水平。结果表明，MEL和5-MTL在抑制鲶鱼卵巢卵黄发生和诱导卵泡闭锁方面均有效。
