Oral treatment with the anti-acne drug Accutane (isotretinoin, 13-cis-retinoic acid) has been associated with suicide ideation and depression. Here, depression-like behaviors (i.e., behavioral despair and anhedonia) were quantified in adult Sprague-Dawley rats gavaged daily beginning at postnatal day (PND) 82 with 13-cis-RA (7.5 or 22.5 mg/kg) or all-trans-retinoic acid (10 or 15 mg/kg ). Tested at PND 130-131 in the Forced Swim Test, 7.5 mg/kg 13-cis-RA marginally decreased immobility and slightly increased climb/struggle durations whereas neither all-trans-retinoic acid group differed from controls. Voluntary saccharin solution (0.03%) intake at PND 102-104 and PND 151-153 was not different from controls in any treated group, although all RA-treated groups had lower intakes. Swim speed in a water maze at PND 180 was similar across groups, indicating no RA-induced differences in physical ability. Open field activity was mildly decreased at PND 91 in 7.5 mg/kg-treated males only, but it was within the control range at PND 119, 147, and 175. Thus, at serum levels similar to those in humans receiving the drug, chronic 13-cis-RA treatment did not severely affect depression-like behaviors in rats. These data do not substantiate the hypothesis of 13-cis-RA-induced depression.

Male infertility is one of the biggest concerns of today's health care community. In the US and other developed countries, approximately 70% of infertility among couples is attributed to male reproductive failure. Alterations in reproductive organ development and sperm production have been listed as the major causes of this phenomenon. Sex determination and differentiation, X chromosome inactivation, gene imprinting and normal germ cell development are important biological processes that, in turn, control mammalian reproduction. Specific patterns of gene expression and repression are important in such processes. The strong correlation between DNA methylation, a major epigenetic modification of the genome, and gene expression patterns is well documented. The effects of DNA methylation on the expression of genes affecting male reproductive organ development, spermatogenesis, and male sexual behavior have been reported, suggesting that alterations in DNA methylation could induce abnormal male sexual development and reproductive performance. Inheritance of epigenetic processes and changes in DNA methylation patterns induced by certain diets have been demonstrated in recent years. However, the effects of DNA methylation on male fertility have not been well studied. Since inherited altered DNA methylation patterns could be a cause of increased susceptibility to xenobiotics or abnormal phenotype in future generations, multigenerational studies oriented to determine the effects of xenobiotics affecting DNA methylation in male fertility are recommended.

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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.

Male and female Sprague-Dawley rats were orally gavaged with 13-cis-retinoic acid (7.5 or 15 mg/kg) or alltrans-retinoic acid (10 or 15 mg/kg) for 7 consecutive days. Blood was collected out to 8 hr after the last gavage on day 7. HPLC serum concentrations of 13-cis-retinoic acid, all-trans-retinoic acid, and 13-cis-4-oxo-retinoic acid were subjected to model independent pharmacokinetic analyses. Peak serum levels of 563 to 1640 ng/ml were observed for rats treated with 13-cis-retinoic acid at 1.5-2 hr after gavage. Peak serum levels of 183 to 267 ng/ml at 1.5 hr after gavage were observed for all-trans-retinoic acids. The elimination half-life of 13-cis-retinoic acid was about 1.5 hr while the elimination half-life of all-trans-retinoic acid was slightly longer. There were no sex differences for any parameter. Serum levels resulting from the 7.5 mg/kg 13-cis-retinoic acid were similar to those of human Accutane A users.While there is some inconsistency in the literature, there are suggestions of depression, suicide ideation, and suicide in human beings treated with 13-cis-retinoic acid (isotretinoin, Accutane A