Possible regulatory factors for intra-abdominal fat mass in a rat model of Parkinson's disease

ObjectivePatients with Parkinson's disease (PD) lose body weight primarily due to decreased body fat mass. The purpose of this study was to elucidate possible factors related to reduction in the intra-abdominal fat mass of 6-hydroxydopamine (6-OHDA)-treated rats, which are frequently used as an animal model for PD.MethodsSham-operated (NPD: n = 4) and unilaterally 6-OHDA-injected (PD: n = 4) 14-wk-old male Sprague-Dawley rats were fed a relatively high-fat diet for 2 wk, during which food intake and body weight were measured. After the 2-wk feeding period, intra-abdominal fat was dissected out and weighed. Carbohydrate and fat absorption-related gene expressions in the jejunum and serum insulin and glucose concentrations were analyzed.ResultsAlthough final body weights did not differ, total intra-abdominal fat weight, expressed relative to body weight, was significantly lower in the PD group than in the NPD group (P < 0.05). There were no significant differences between the two groups in the mRNA expression of carbohydrate and fat digestion/absorption-related genes in the jejunum, or in fat absorption efficacy assessed by fecal fat excretion. However, PD rats showed significantly lower serum insulin and higher glucose concentrations than NPD rats (P < 0.05).ConclusionPD model rats displayed loss of intra-abdominal fat, similar to the progressive loss of fat in PD patients. Our results provide preliminary evidence that reduced lipogenesis due to lower insulin levels, rather than impaired digestion/absorption, might have been involved in this decrease in intra-abdominal fat mass.