Possible Glucogenicity of Butyrate in Sheep

THE virtual dependence of ruminants on endogenous sources of glucose and the relative abundance of short-chain fatty acids have stimulated much discussion on the possible existence in ruminant tissues of pathways leading to the net conversion of fatty acids to glucose. Butyrate, in particular, has been the subject of controversy since Potter 1 found that sodium butyrate injected intravenously relieved insulin convulsions. Several investigators have observed raised blood sugar concentrations following butyrate administration 2–6 , and Shaw 7 has reported the net conversion of large amounts of butyrate to carbohydrate by the perfused goat liver. Kleiber et al. 8 obtained appreciable labelling of milk lactose following the intravenous administration of labelled butyrate in cows, but more recently, the absence of pathways which would account for the ‘glucogenic’ behaviour of butyrate in the lactating cow has been convincingly demonstrated 9 . Lauryssens, Verbeke, Peeters and Reinards 10 compared the incorporation into cow's milk constituents of butyrate labelled in the C-1 or C-3 positions and concluded that butyrato metabolism proceeded after cleavage into two-carbon fragments, a well-established pathway in other tissues.