注射和口服GnRH对小黄鱼人工催产效果的评估

EVALUATION OF THE ARTIFICIAL OXYTOCIN EFFECT OF GNRH INJECTION AND ORAL ADMINISTRATION ON SMALL YELLOW CROAKER (LARIMICHTHYS POLYACTIS)

  • 摘要: 为评估促性腺激素释放激素(Gonadotrophin releasing hormone, GnRH)作为外源激素对小黄鱼(Larimichthys polyactis)的人工催产繁殖效果, 以生理盐水注射组为对照, 设计促黄体素释放激素(LHRH-A2, 2.4 μg/kg)注射组、促性腺激素释放激素(GnRH, 75 μg/kg)注射组、促性腺激素释放激素(6 mg/kg)口服组, 通过繁殖生理学等方法比较其产卵情况、卵巢组织生理学变化和血清激素水平综合分析催产效果。结果显示, GnRH注射组在效应时间、产卵持续时间及受精率和孵化率与LHRH-A2注射组无显著差异, 但总产卵量和上浮卵重显著升高(P<0.05); GnRH口服组总产卵量和上浮卵重则显著低于LHRH-A2注射组, 但受精率和孵化率无显著差异。进一步通过组织生理学分析小黄鱼产卵过程, 对照组卵巢发育以Ⅲ期卵巢为主, LHRH-A2注射组、GnRH注射和口服组均可诱导卵巢由Ⅲ期发育至Ⅴ期, 促进卵母细胞由Ⅲ和Ⅳ时相发育成熟并排出体外。各实验组经催产激素处理后, 血清中促黄体生成素(LH)、卵泡刺激素(FSH)和GnRH迅速上升, 至产卵后期仍维持较高水平, 各处理组的激素水平变化趋势一致。综上, 注射GnRH可有效诱导小黄鱼产卵, 且催产效果与注射LHRH-A2无显著差异; 口服GnRH也可以诱导小黄鱼产卵, 但产卵量和上浮卵重显著低于激素注射组, 对其给药方法和剂量需要进一步优化。

     

    Abstract: Marine economic fish such as Larimichthys crocea and Larimichthys polyactis cannot spawn spontaneously under artificial indoor breeding conditions, so they need artificial oxytocin to ovulate normally. The traditional way of artificial oxytocin is to give injections to the parent fish and squeeze eggs will cause great stress response, sometimes even die from stress, resulting in the reduction of the parent fish population. Oxytocin requires a lot of manpower and resources, therefore, a low-cost and effective way of oxytocin should be found. To evaluate the effect of gonadotrophin releasing hormone (GnRH) as an exogenous hormone on the spawning of small yellow croaker (Larimichthys polyactis), the saline injection group was used as the control, and the luteinizing hormone releasing hormone (LHRH-A2, 2.4 μg/kg) injection group, the gonadotrophin releasing hormone (GnRH, 75 μg/kg) injection group and gonadotropin-releasing hormone (GnRH, 6 mg/kg) oral administration group were designed to analyze the egg production, ovarian development changes and serum hormone levels. The results showed that the GnRH-injected group did not differ significantly from the LHRH-A2-injected group in terms of the initial spawning time and duration, while the total spawning quantity, fertilization rate and hatching rate were significantly higher (P<0.05). Histological analysis of the spawning process showed that the LHRH-A2 injection group as well as GnRH injection and oral administration induced ovarian development from stage Ⅲ to stage Ⅴ, and promoted oocyte maturation and excretion from stages Ⅲ and Ⅳ. Serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and GnRH, increased rapidly with exogenous hormone treatment and could be maintained until late oviposition. Similar trends were observed in all treatment groups. In summary, GnRH injection could induce the spawning of the small yellow croaker and the effect of spawning was not significantly different from that of LHRH-A2. Oral administration of GnRH could induce spawning in small yellow croaker as well, but the spawning quantity and buoyant egg weight were significantly lower than those of the hormone injection groups. Further optimization of the oral administration of GnRH is needed in the future. The results provide a certain reference basis for further optimizing and supplementing the oxytocin mode of small yellow croaker, and oral hormone method is also a powerful tool to induce the spawning of small ornamental fish with too large body size and inconvenient operation.

     

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