Lipid metabolism of viviparous stingray Potamotrygon falkneri Castex & Maciel, 1963 during reproduction

Abstract

Seasonal changes in body composition have been observed in several species of vertebrates, and these changes appear to be related to the vitellogenesis, as well as other processes associated with maternal-fetal transfer and offspring survival. In the case of stingrays, the metabolic distribution and commitment of energy reserves for reproduction will certainly extend to post-vitellogenic periods, since the reproductive success of these species will depend on the development of the trophonema and uterine milk, which will serve as a nutritional base for the embryos until the time of parturition. The objective of this work was to investigate the pattern of storage, mobilization and use of lipid substrates and fatty acids involved with the reproduction of the species Potamotrygon falkneri in different phases of the reproductive cycle. The animals collected were anesthetized and euthanized, with subsequent extraction and determination of the total lipid concentration and fatty acid profile of the liver, muscle, ovarian and uterine tissues. After collections and macroscopic analysis of the ovaries, the animals were separated into three groups, corresponding to the reproductive stages: Rest, Vitelogenesis and Mature. The results support the hypothesis that the lipid histotrophic strategy of Myliobatiformes, showing apparent lipid storage in the uterine tissue during the maturation of the animals, culminating in the highest values sampled in the mature period. The uterine and hepatic tissues showed concentrations up to 100 times higher than lipids in comparison with muscle and ovarian tissue, corroborating the stored role of this substrate in these tissues. The fatty acid profile showed a pattern of fatty acid mobilization from the liver and muscle tissues to the uterine tissue, notably to polyunsaturated fatty acids (total, omega 3 and omega 6) important in the development of embryos and juveniles.