Retinoids in marine mammals and their use as biomarkers of organochlorine compounds

Retinoids, also known as vitamin A, are non-endogenous molecules that essential for a number of physiological processes in mammals. Imbalance retinoids has been associated with reproductive impairment, embryonic mortality, growth retardation and bone deformities, pathologies skin the nervous system, immune suppression. Mammals cannot produce so their primary source is dietary. They absorbed by small intestine packaged retinyl esters chylomicrons, which enter circulation end up mostly liver fatty tissues. Plasma retinoid levels homeostatically regulated, they remain constant despite variations dietary supply or tissue stores. Therefore body depletion be reliably assessed through blood, should evaluated concentrations depot In marine mammals, main storage sites blubber. Although not universal rule, concentration often increases age both sexes because progressive build-up esters. addition, sex affects levels, but nature magnitude this effect varies between species populations. Taxonomic, life-style (particularly dietary) climatic differences may explain dissimilarities on levels. For reason, can used to distinguish populations population components showing distinct dietary, behavioural, other traits. Disease, particularly when affecting organs importance inducing malnutrition, affect care taken studying stranded animals. Organochlorine compounds, PCBs, dioxin (TCDDs) DDTs, increase mobilisation from hepatic extrahepatic into serum, accompanied enhanced degradation elimination urine. terrestrial concentration. Conversely, some mammals plasma have reported decrease exposure organochlorines increases, although mechanisms unclear. However, given homeostatic regulation variation expected less than Because vary even at moderate organochlorines, original restored such decreases disappears, biomarker impact pollutants Further research needed validate use, cetaceans.