The effect of alpha-ketoglutarate on a piscine skin model: a molecular and morphological study

Dissertação mest., Ciências Biomédicas, Universidade do Algarve, 2009Alpha-ketoglutarate (AKG) is a key intermediate in the tricarboxylic acid cycle with important functions in glutamate and glutamine metabolism. Its effect after oral administration was studied in adult sea bream Sparus aurata skin and scales in order to evaluate the effect on collagen synthesis. Scales were removed from one side of the body and allowed to regenerate for 14 days; the control group received untreated food, the AKG (calcium salt) group received 0.1g/kg in the diet (Gramineer International AB) and the placebo group received food treated with 140 mg calcium pills. AKG administration did not affect cortisol, estradiol, calcium or phosphorus levels in sea bream plasma, but the levels of aspartate-aminotransferase (AST) were higher in the AKG treated group when compared to the Control. AKG administration did not modify the overall organisation of the sea bream skin or of scale regeneration, as observed after tissue staining with Masson’s Trichrome. However, in the epidermis of the AKG treated group, the basement membrane was thicker than in the other groups both in the intact and regenerated scale, as revealed by birefringence under polarized light, which revealed a strong yellow band corresponding to collagen type I that was not observed in the control or placebo groups. Scale osteoblasts were identified by in situ hybridization with specific riboprobes and osteoclasts by TRAP staining and the content of ColIα1 and osteopontin in intact and regenerating skin was evaluated by qPCR. No differences in the expression of these two genes were observed between experimental groups, but an adequate reference gene still needs to be identified. Assessment of the elastic recoil of aortas from each experimental group revealed it was significantly higher in the AKG group compared to the control and this modification in rats was associated with an increase in collagen synthesis. This is in agreement with the increase in collagen detected in the skin by birefringence under polarized light in AKG treated fish although this observation will require confirmation by quantification of the collagen. In conclusion, the results of the present study provide evidence that AKG administration modifies collagen synthesis in sea bream. Further studies are required to confirm the effect of AKG on collagen synthesis and its mechanism of action during skin and scale regeneration

Hybrid threats in the context of european security: report of the international conference organized at the National Defence Institute (IDN) on 18 May 2021 under the framework of the Portuguese Presidency of the Council of the European Union

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