Serum levels of albumin, triglycerides, total protein and glucose in rats are altered after oral treatment with low doses of 13-cis-retinoic acid or all-trans-retinoic acid.

Currently used to treat severe acne, 13-cis-retinoic acid (13-cis-RA) is under investigation for its anticancer effects as is the isomer, all-trans-retinoic acid (all-trans-RA). Here, the effects of oral 13-cis-RA or all-trans-RA treatment on serum chemistry, leptin and adiponectin levels were evaluated. Adult Sprague-Dawley rats were gavaged once daily for 7 consecutive days with 13-cis-RA (7.5 or 15 mg kg(-1)), all-trans-RA (10 or 15 mg kg(-1)) (n=24/sex/dose), or soy oil (n=16/sex) and blood was sampled 30-480 min after the last gavage. The body weight was unaffected; however, the liver/body weight ratios were increased by both doses of all-trans-RA. Sex differences were noted for levels of cholesterol, creatine, triglycerides, albumin, alanine aminotransferase and total protein. Both doses of all-trans-RA reduced albumin levels to approximately 90% of the control and total protein levels to approximately 93% of the control while substantially elevating triglyceride levels to approximately 66%-99% above the control. Additionally, triglyceride levels of the 15 mg kg(-1) 13-cis RA group were approximately 62% higher than the controls and total protein levels were approximately 5% less. Glucose levels were affected by sex and RA treatment in that males treated with 15 mg kg(-1) of 13-cis-RA or 10 mg kg(-1) all-trans-RA had lower (13%-19%) levels than the same-sex controls; however, females were not similarly affected. Neither 13-cis-RA nor all-trans-RA treatment had significant effects on the levels of blood urea nitrogen, aspartate amino transferase, leptin or adiponectin. On a mg kg(-1) basis, all-trans-RA was more potent than 13-cis-RA. These results replicate previous findings of RA-induced increased triglyceride levels. Additionally, several new findings indicate there may be sex-specific effects of RA treatment. Finally, neither treatment appeared to alter the typical diurnal cycles of these endpoints. Copyright (c) 2005 John Wiley & Sons, Ltd.