Title

 

Authors

A. Signorile¹, N. Sardaro¹, D. De Rasmo¹, S. Papa^1,2, P. Borracci³, M.R. Carratù^3
 
1Dept. of Medical Biochemistry, Biology and Physics (DIBIFIM), University of Bari “Aldo Moro”, Italy; ²Institute of Biomembranes and Bioenergetics, Italian Research Council (CNR), Bari, Italy; ³ Dept. of Biomedical Sciences and Human Oncology, Section of Medical Pharmacology, University of Bari “Aldo Moro”, Italy.

 

Abstract

Retinoic acid (RA) is used as a therapeutic agent in a number of clinical disorders including leukaemia, psoriasis and acne. The excesses or deficiencies are harmful, and, more compellingly, RA is a known human teratogen at very low doses. Indeed, the RA treatment during early stages of pregnancy may result in severe malformations of the foetus. In previous works it has been reported that all-trans RA (ATRA) treatment (2.5 mg/kg b.w., intragastric intubation) at gestational days (GD) 11-13 produces, in the offspring of Sprague-Dawley rats, neurofunctional deficits, mostly attributable to changes in the cerebellar phenotype (Coluccia et al., 2008). Moreover, there is evidence that complex I of the mitochondrial respiratory chain is particularly sensitive to treatment with retinoic acid. In cultured keratinocytes, retinoic acid decreases the activity of complex I and induces cell growth arrest (Papa et al., 2007). This work was aimed to determine whether the neurofunctional deficits induced by ATRA could be ascribed to impairment in the mitochondrial function of the cerebellum, in particular the complex I activity. The measurement of the enzymatic activity of complex I and complex IV on postnatal days (PND) 3, 8, 15 and 21 showedan age-dependent increase in vehicle-treated (control) rats during this critical window of the postnatal brain growth  spurt. Conversely, the ATRA treatment led to arrest of this physiological increase in complex I activity, an effect that became highly significant on PND 21. The decreased activity of complex I was not associated with an altered expression of its subunits.Complex I is particularly sensitive to oxidative insults, and in particular oxidative stress is associated with nytrosylation and carbonylation of its subunits (Folbergrova’ et al., 2010). To test the oxidative stress state, we measured GSH and GSSG levels, glutathione peroxidase and SOD activities, but no differences were found between vehicle- and ATRA-treated rats. Interestingly, we have found an inverse correlation between the increased carbonyl groups in mitochondria and the decreased activity of complex I. Analysis of carbonylation of complex I revealed an increased oxidation of its subunits in ATRA-treated with respect to vehicle-treated rats. In conclusion, our results suggest that the ATRA treatment during the critical GD 11-13 developmental window, could induce a perturbation of the system clearing damaged subunits of complex I with consequent  impairment in its activity.
 
Coluccia  et al. (2008). Neurotoxicology and Teratology, 30:395-403.
Papa et al. (2007). Int J Immunopathol Pharmacol.,20(4):719-29.
Folbergrova’et al. (2010).Neurochem Int., 56(3):394-403.