O efeito da hipóxia sobre o metabolismo e a expressão dos genes HIF-1α e VEGF do ciclídeo amazônico Astronotus ocellatus (Agassiz, 1831)

Abstract

Amazonian fishes exhibit a variety of strategies related to oxygen uptake in response to shortages of gas into water, related to their lifestyle and evolution. The Astronotus ocellatus is a species of extreme tolerance to hypoxia and some of their physiological, biochemical and molecular techniques could be evaluated in this study. Under conditions of severe hypoxia (0.5 mgO2 / L) the hematological parameters are primary responses and were adjusted to increase and make more efficient the carrying of oxygen to tissues, observed by the increase of hematocrit, the number of circulating erythrocytes and hemoglobin concentration. Furthermore, increased glucose demonstrated its importance in the supply of carbohydrate metabolism, especially in anaerobic glycolysis, in times of shortage of oxygen. Another strategy, and perhaps most important in increasing tolerance to hypoxia of the species was widespread suppression of metabolism evidenced by the reduction in activity of enzymes MDH and CS in tissues such as liver, heart and brain, as well as reducing glycolytic enzyme LDH in the brain. Increased expression of HIF-1α and VEGF genes in conditions of severe hypoxia revealed the importance of these, respectively, in the transcription of specific target genes related to hypoxia and increased vascularity of tissues, facilitating the transport of oxygen through the blood. As the oscar experiencing situations of daily fluctuation in oxygen levels in their natural habitat, an important strategy in the face of these periodic events is rapid and adequate recovery after hypoxic stress, observed in this work through the reorganization of hematological parameters, the enzymatic machinery and transcription of essential genes for the resumption of oxygen.