Lin Tingting, Liu Xin, Xiao Dongxue, Zhang Dong
Key Laboratory of East China Sea and Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, People's Republic of China.
Fish Physiol Biochem. 2017 Jun;43(3):889-899. doi: 10.1007/s10695-017-0343-6. Epub 2017 Feb 14.
To better understand the endocrine- and immune-response pattern during reproduction in a fish species having parental care behaviors and also to accumulate the endocrine- and immune-related data for future explanations of the low reproductive efficiency in seahorse species, the variations of immune factors and sex steroids in the plasma of the male lined seahorse Hippocampus erectus at different breeding stages, i.e., pre-pregnancy, pregnancy (early, middle, and late periods), and post-pregnancy, were investigated in the present study. The immune factors included monocytes/leucocytes (M/L), leucocyte phagocytic rate (LPR), immunoglobulin M (Ig M), interleukin-2 (IL-2), interferon-α (IFN-α), and lysozyme (LZM). The sex steroids included testosterone (T), 11-ketotestosterone (11-KT), 11β-hydroxytestosterone (11β-OHT), 17α-methyltestosterone (17α-MT), 17β-estradiol (E2), and 17α-hydroxy-20β-dihydroprogesterone (17α-20β-P). Moreover, the immune metabolic activity of epithelium cells in the brood pouch at different breeding stages was also analyzed through ultrastructural observations of the abundance of cytoplasmic granules, mitochondria, endoplasmic reticulum, lysosomes, and exocytosis. The results show that a higher immune level was observed during pregnancy, particularly in the early and middle periods, and a lower immune level was noted during pre-pregnancy. Correspondingly, the epithelium cells in the brood pouch also showed a stronger immune metabolic activity during pregnancy and weaker activity during pre-pregnancy. Four sex steroids of T, 11β-OHT, 17α-MT, and E2 were higher during pre-pregnancy and lower during post-pregnancy, whereas 11-KT and 17α-20β-P, which were positively correlated with part immune factors, were higher during pregnancy. No negative correlations between sex steroids and immune factors were observed. In conclusion, the higher immune competence during pregnancy may indicate that parental care could improve immunity, which may be the major factor for no immunosuppressive effect of sex steroids during reproduction in the seahorse H. erectus, unlike noncaregiving fishes in which inhibitions of sex steroids on immunity are frequently observed. Moreover, higher 11-KT and 17α-20β-P during pregnancy than during pre-pregnancy and post-pregnancy may suggest that these two steroids are also involved in parental care regulation.
为了更好地了解具有亲代抚育行为的鱼类在繁殖过程中的内分泌和免疫反应模式，并积累内分泌和免疫相关数据，以便未来解释海马物种繁殖效率低下的原因，本研究调查了雄性直立海马（Hippocampus erectus）在不同繁殖阶段，即怀孕前、怀孕期（早期、中期和晚期）和产后，血浆中免疫因子和性类固醇的变化。免疫因子包括单核细胞/白细胞（M/L）、白细胞吞噬率（LPR）、免疫球蛋白M（Ig M）、白细胞介素-2（IL-2）、干扰素-α（IFN-α）和溶菌酶（LZM）。性类固醇包括睾酮（T）、11-酮睾酮（11-KT）、11β-羟基睾酮（11β-OHT）、17α-甲基睾酮（17α-MT）、17β-雌二醇（E2）和17α-羟基-20β-二氢孕酮（17α-20β-P）。此外，还通过对育儿袋中上皮细胞的细胞质颗粒、线粒体、内质网、溶酶体和胞吐作用丰富程度的超微结构观察，分析了不同繁殖阶段育儿袋中上皮细胞的免疫代谢活性。结果表明，怀孕期的免疫水平较高，尤其是在早期和中期，而怀孕前的免疫水平较低。相应地，育儿袋中的上皮细胞在怀孕期也表现出较强的免疫代谢活性，而在怀孕前则较弱。四种性类固醇T、11β-OHT、17α-MT和E2在怀孕前较高，产后较低，而与部分免疫因子呈正相关的11-KT和17α-20β-P在怀孕期较高。未观察到性类固醇与免疫因子之间存在负相关。总之，怀孕期较高的免疫能力可能表明亲代抚育可以提高免疫力，这可能是直立海马在繁殖过程中性类固醇没有免疫抑制作用的主要因素，这与经常观察到性类固醇对非亲代抚育鱼类免疫力有抑制作用的情况不同。此外，怀孕期的11-KT和17α-20β-P高于怀孕前和产后，这可能表明这两种类固醇也参与了亲代抚育调节。
