RESUMO
AIM: We tested the effects of a cancer cachexia-anorexia sydrome upon the balance of anti and pro-inflammatory cytokines in the hypothalamus of sedentary or trained tumour-bearing (Walker-256 carcinosarcoma) rats. METHODS: Animals were randomly assigned to a sedentary control (SC), sedentary tumour-bearing (ST), and sedentary pair-fed (SPF) groups or, exercised control (EC), exercised tumour-bearing (ET) and exercised pair-fed (EPF) groups. Trained rats ran on a treadmill (60%VO2max) for 60 min/d, 5 days/wk, for 8 wks. We evaluated food intake, leptin and cytokine (TNF-α, IL1ß) levels in the hypothalamus. RESULTS: The cumulative food intake and serum leptin concentration were reduced in ST compared to SC. Leptin gene expression in the retroperitoneal adipose tissue (RPAT) was increased in SPF in comparison with SC and ST, and in the mesenteric adipose tissue (MEAT) the same parameter was decreased in ST in relation to SC. Leptin levels in RPAT and MEAT were decreased in ST, when compared with SC. Exercise training was also able to reduce tumour weight when compared to ST group. In the hypothalamus, IL-1ß and IL-10 gene expression was higher in ST than in SC and SPF. Cytokine concentration in hypothalamus was higher in ST (TNF-α and IL-1ß, p < 0.05), compared with SC and SPF. These pro-inflammatory cytokines concentrations were restored to control values (p < 0.05), when the animals were submitted to endurance training. CONCLUSION: Cancer-induced anorexia leads towards a pro-inflammatory state in the hypothalamus, which is prevented by endurance training which induces an anti-inflammatory state, with concomitant decrease of tumour weight.
RESUMO
PURPOSE: There is controversy as to the use of intramuscular triacylglycerol (IMTAG) during exercise and to whether endurance training increases its utilization, despite the various methodologies used to address these questions. We used a histological-morphometrical approach to study the relative contribution of the two compartments of IMTAG storage, intramyocellular, and perimysial adipocytes, during exercise in sedentary and endurance-trained rats. METHODS: After osmium impregnation, the soleus (SOL) and gastrocnemius (GAS) were studied under light and electron microscopy. IMTAG content (after Triton WR1339 treatment or not) and 14C-oleate incorporation into the muscles were studied. RESULTS: In GAS, training, but not exercise alone, decreased extramyocellular lipid (P < 0.001 vs sedentary), an effect not found for SOL. Both muscles presented reduced lipid inclusion number (P < 0.001) and area (P < 0.05), immediately after exercise in sedentary and trained rats. For SOL, a greater number (P < 0.001 vs sedentary) of inclusions was found 24 h after exercise in trained rats. Triton WR1339 treatment decreased IMTAG content 12 h after exercise in SOL (but not in GAS), in sedentary (33%), and trained rats (52%). CONCLUSIONS: The multi-analytical approach adopted allowed the discernment between the IMTAG compartments and provided evidence for an effect of training upon storage of lipid in perimysial adipocytes in rat gastrocnemius, as well as clearly showed that the IMTAG mobilized during submaximal exercise in sedentary and trained rats derives from intramyocellular lipid, both in SOL and GAS. Moreover, the reposition of these stores 12 h after exercise was shown to be different in GAS and SOL, as plasma triacylglycerol clearly contributed to the process only in the latter, possibly reflecting the differences in lipoprotein lipase activity in the muscles reported by others.
