Formulação e efeito do tratamento de uma nanoemulsão de óleo de milho rico em canabidiol sobre o comportamento e parâmetros testiculares de ratos com autismo induzido por ácido valpróico

Abstract

Autism is a neurodevelopmental disorder mainly characterized by impaired communication, social, and cognitive development. Cannabidiol (CBD) is a lipophilic cannabinoid, which has pharmacological effects on the central nervous system that can bring benefits to autistic individuals since there is no standard drug treatment available. Nanoemulsions are delivery systems that increase the water solubility and bioavailability of lipophilic compounds such as cannabidiol. This study proposed the formulation of a corn oil nanoemulsion rich in cannabidiol, as well as evaluating the effect of this nanoemulsion on behavioral changes and testicular parameters in an animal model of autism induced by valproic acid (VPA). Nanoemulsions were developed with CBD oil at different concentrations (5, 10, and 20%) and the macroscopic and physicochemical characteristics were evaluated. The formulations were stable after thermal stress and centrifugation, and showed a droplet size smaller than 200 nm, in addition to a reduced polydispersity index and zeta potential, characterizing their homogeneity. For the induction of autism, 10 female rats received 500 mg/kg of VPA diluted in saline solution or saline solution alone intraperitoneally during the prenatal period. Males born from females exposed to VPA constituted the VPA group (positive control), CBDON1 (treated with 10% oil nanoemulsion), and CBDON2 (treated with 10% oil nanoemulsion). Males born from females exposed to saline solution constituted the control group (negative). Five behavioral tests were performed in which anxiety, locomotor and exploratory activity, stereotypes, sociability index, and social preference index were evaluated. Animals exposed to VPA during the prenatal period showed an increase in anxiety and stereotypes, and a reduction in exploratory activity, sociability index and social preference index, behavioral alterations compatible with autism. The analysis of testicular morphometric alterations was performed based on the analysis of the morphometry of the seminiferous tubules, volumetric density, and volume of the tubular components, percentage and volume of the intertubule components, and stereological and morphometric parameters of the Leydig cells. Prenatal exposure to VPA generated an increase in testicular size, diameter, volume, and length of seminiferous tubules, lumen diameter, tubulosomatic index, somatic epithelial index, as well as increased volume of the nucleus, the cytoplasm of Leydig cells, and levels of the antioxidant enzymes superoxide dismutase (SOD) and glutathione (GST). On the other hand, exposure to VPA reduced the height and volumetric density of the epithelium, as well as decreased serum testosterone levels. Treatment with CBD nanoemulsions was effective in reversing behavioral changes compatible with autism, reducing neuronal death in the hippocampus, improving testicular parameters, and attenuating the reduction in testosterone levels generated by prenatal exposure to valproic acid. However, the formulations did not change SOD and GST levels, as the increase in enzyme activity may not have been necessary due to probable prevention against tissue damage generated by CBD.