Sex differences in the magnitude of diabetic ocular surface complications: Role of serum OGF

Diabetes is associated with dysregulation of the Opioid Growth Factor (OGF) - OGF receptor (OGFr) regulatory pathway leading to elevated OGF levels in serum and tissues. This study was designed to investigate the role of sex on the magnitude of ocular surface complications by direct comparison of male and female type 1 diabetic (T1D) rats. Male and female adult Sprague-Dawley rats were rendered T1D; a cohort of T1D male and female rats received insulin (=T1D-INS). Tear production, corneal surface sensitivity, as well as serum levels of estrogen, testosterone, OGF and OGFr were measured. Multivariate analyses were performed for correlations between sex, condition and magnitude of ocular surface alterations. Significant differences were noted in all parameters tested between male and female Normal, T1D, and T1D-INS animals over the 8-week observation period. Multivariate analyses revealed that the magnitude of complications is greater in female T1D rats and has a strong negative correlation with serum estrogen and OGF. Ocular surface complications associated with T1D have an earlier onset and greater magnitude in female T1D rats than male diabetic animals, and are related to elevated levels of OGF.