Effects of high molecular weight water-soluble chitosan on in vitro fertilization and ovulation in mice fed a high-fat diet.

A high molecular weight water-soluble chitosan (WSC) with an average molecular weight of 300 kD and a deacethylation level of over 90% was produced using a simple multi-step membrane separation process. It is known that WSC prevents obesity induced by a high-fat diet. Consequently, this study investigated whether or not WSC improved the ovarian dysfunction caused by obesity in mice. The mice were fed a high density protein and lipid diet for 4 weeks, followed by the administration of WSC at 480 mg/kg body weight per day for 4 days. Thereafter, the changes in body weight, ovulation rate, in vivo and in vitro fertilization and embryonic development were measured. WSC markedly reduced the body weight of obese mice fed with a high-fat diet, but not in mice fed with a normal diet. WSC had significant effects on the ovulation rate, both the in vivo and in vitro fertilization rates and embryonic development. These results indicate an improvement in the ovarian and oviduct dysfunction caused by obesity, and suggest an adjustment in the internal secretions and metabolic functions.