Lipid metabolism of rays Potamotrygon falkneri during reproduction

Abstract

Stingrays of Myliobatiformes Order are considered histotrophic viviparous, due to the fact that embryos are nurtured by secretion of villiform mucous produced by the mother uterus, known as trophonema, which is rich in lipids ("uterine milk") and proteins of high molecular weight. It is well known and studied that, during the reproductive cycle of fish, under the hormone regulation of the hypothalamus-pituitary-gonads axis, metabolic reserves are reorganized, with actual changes in muscle composition, adiposity tissue and liver, which has its reservations reduced and mobilized to the gonads, especially in females, who have hepatic metabolism stimulated during the vitelogenesis process. Seasonal changes in body composition (water, lipids and proteins storage) has been observed in various species of fish, and these changes seem to be related to the growth and development of the gonads, and other processes associated with spawning. In the case of rays certainly metabolic distribution and commitment to energy reserves for reproduction extend to post-vitellogenic periods since reproductive success of these species will depend on the development of trophonema and uterine milk, which will serve as a nutritional basis for the embryos to the time of birth. In this way it is important to understand the physiological processes related to reproductive dynamics, physiological adaptations associated with maternal and fetal trophic relationship and the allocation of distinct patterns of lipid classes during pregnancy, which can reflect nutritional and environmental characteristics in the elected species.