Ciliary neurotrophic factor restores gallbladder contractility in leptin-resistant obese diabetic mice

Background. Obesity and diabetes are major risk factors for cholesterol gallstones, and the majority of obese people are leptin-resistant. Our previous work has shown that both leptin-deficient (Lep^ob) and leptin-resistant (Lep^db) obese diabetic mice have decreased in vitro gallbladder motility. Leptin administration to leptin-deficient (Lep ^ob) animals restores gallbladder motility and reverses obesity and hyperinsulinemia. However, additional leptin in leptin-resistant obesity would not be expected to improve obesity-related parameters. Recent studies demonstrate that ciliary neurotrophic factor (CNTF) reduces weight and hyperinsulinemia in leptin-resistant obesity. Our hypothesis is that CNFT would cause weight loss, lower blood sugars, and restore gallbladder contractility in leptin-resistant (Lep^db) mice. Materials and methods. 20 C57b/6J and 20 Lep^db 8-week-old female mice were injected daily with either intraperitoneal saline or 0.3 μg/g CNTF_Ax15 for 17 days. Gallbladders were mounted in muscle baths and stimulated with acetylcholine, neuropeptide Y, and cholecystokinin. Gallbladder volume, serum glucose, insulin, liver weight, liver fat, and gallbladder responses were measured. Data were analyzed by ANOVA. Results. Saline treated obese mice had greater body weight and obesity parameters, but decreased gallbladder contractility to neurotransmitters compared to saline treated lean mice. CNTF administration to obese mice decreased body weight and obesity parameters, and restored gallbladder contractility. CNTF treated lean animals had weight loss and decreased gallbladder contraction to acetylcholine and cholecystokinin compared to saline treated lean animals. Conclusions. Ciliary neurotrophic factor (CNTF) causes 1) weight loss, 2) improvement of diabetes, and 3) alterations in gallbladder motility that is improved in obese mice but decreased in lean mice. We conclude that CNTF may improve gallbladder contractility in leptin-resistant obesity with diabetes.