Hormonal modulation of delta6 and delta5 desaturases: case of diabetes.
Animal biosynthesis of high polyunsaturated fatty acids from linoleic, alpha-linolenic and oleic acids is mainly modulated by the delta6 and delta5 desaturases through dietary and hormonal stimulated mechanisms. From hormones, only insulin activates both enzymes. In experimental diabetes mellitus type-1, the depressed delta6 desaturase is restored by insulin stimulation of the gene expression of its mRNA. However, cAMP or cycloheximide injection prevents this effect. The depression of delta6 and delta5 desaturases in diabetes is rapidly correlated by lower contents of arachidonic acid and higher contents of linoleic in almost all the tissues except brain. However, docosahexaenoic n-3 acid enhancement, mainly in liver phospholipids, is not explained yet. In experimental non-insulin dependent diabetes, the effect upon the delta6 and delta5 desaturases is not clear. From all other hormones glucagon, adrenaline, glucocorticoids, mineralocorticoids, oestriol, oestradiol, testosterone and ACTH depress both desaturases, and a few hormones: progesterone, cortexolone and pregnanediol are inactive.
Brenner
Rodolfo R
RR
Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, calles 60 y 120, 1900-La Plata, Argentina. rbrenner@atlas.med.unlp.edu.ar
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D000090943:Delta-5 Fatty Acid Desaturase; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D004281:Docosahexaenoic Acids / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000201:enzymology; D044943:Fatty Acid Desaturases / Q000378:metabolism / Q000502:physiology*; D006728:Hormones / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D050602:Linoleoyl-CoA Desaturase; D008954:Models, Biological; D008956:Models, Chemical; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
D000090943:Delta-5 Fatty Acid Desaturase; D006728:Hormones; D007328:Insulin; D012333:RNA, Messenger; D004281:Docosahexaenoic Acids; D016718:Arachidonic Acid; D003513:Cycloheximide; D000242:Cyclic AMP; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase