Enzyme activity of rat tibialis anterior muscle differs between treatment with triamcinolone and prednisolone and nutritional deprivation

The maximal activity of a selection of enzymes involved in muscle carbohydr ate handling, citric acid cycle and fatty acyl beta-oxidation were studied after treatment with the fluorinated corticosteroid triamcinolone and compa red to a similar treatment of the non-fluorinated corticosteroid prednisolo ne in an equipotent anti-inflammatory dose. Furthermore, because triamcinol one causes loss of body mass and muscle wasting, the effects of triamcinolo ne were investigated relative to a control group, with the same loss of bod y mass, due to nutritional deprivation. The study was performed in male Wis tar rats in the following treatment groups: TR, triamcinolone treatment (0. 25 mg . kg . day(-1) for 2 weeks), which resulted in a reduction of body ma ss (24%), ND, nutritional deprivation (30% of normal daily food intake for 2 weeks) resulting in a similar (24%) decrease of body mass as TRI PR, pred nisolone treatment (0.31 mg . kg(-1) . day(-1) for 2 weeks), with a 10% inc rease in body mass: FF, free-fed control group, with a 12% increase in body mass in 2 weeks. Compared to FF, TR induced an increase in phosphofructoki nase (PFK) activity (P < 0.01). glycogen synthase [GS(i + d)] activity (P < 0.05) and glycogen content (P < 0.01) in the tibialis anterior muscle. The PR and ND caused no alterations in PFK or citrate synthase (CS) activity c ompared to FF. Compared to PR? TR induced an increase in PFK (P < 0.01), CS (P < 0.05) and GS(i + d) activity (P < 0.01), Both TR and PR caused an inc reased muscle glycogen content. being more pronounced in TR (P < 0.05). Com pared to ND, TR induced all increased CS (P < 0.05) and GS(i + d) activity( P < 0.01) and glycogen content (P < 0.01), The ND resulted in a decreased g lycogen content compared to FF (P < 0.05), None of the treatments affected the activity of glycogen phosphorylase, beta-hydroxyacyl coenzyme A dehydro genase and lactate dehydrogenase. It was concluded that corticosteroids led to an increased muscle glycogen content; however, the changes In the enzym es of carbohydrate metabolism were corticosteroid type specific and did not relate to undernutrition, which accompanied the triamcinolone treatment.