Toxic effects of methyl methacrylate monomer on male genital tissues. In vitro study in rats.

INTRODUCTION Methyl methacrylate (MMA), a widely used monomer in dentistry and medicine has been reported to cause abnormalities or lesions in several organs. Experimental and clinical studies have documented that monomers may cause a wide range of adverse health effects such as irritation to skin, eyes, and mucous membranes, allergic dermatitis, stomatitis, asthma, neuropathy, disturbances of the central nervous system, liver toxicity, and fertility disturbances. OBJECTIVES The purpose of this study was to determine whether MMA mixed with water at four different concentrations is able to affect the histological structure of testicular tissues and seminal vesicle on male rats. METHODS The target population consisted of 60 male Sprague-Dawley rats. They were housed in colony cages and divided into five groups: The first group (n=15) designated as the control group and four experimental groups (n=45). Experiments were conducted by exposing the four experimental groups to MMA administered per os mixed with water at different concentrations (4% per hundred, 8% per hundred, 16% per hundred, 32% per hundred). The exposure duration was eight months. The testicles and the seminal vesicles were then extracted, dissected, fixed in Bouin liquid fixative and were submitted to the pathology laboratory (National Institute of Pathology) for histopathological examination. RESULTS Seven out of 10 rats to which the MMA was administrated at a concentration of 32% per hundred showed partial seminal vesicle atrophy. The seminal vesicles in the remaining rats showed normal histology in all specimens. Testis, epididymis and vas deferens showed normal histology in all rats. CONCLUSION The data in this study showed that MMA administered at high concentration is associated to seminal vesicle atrophy. These findings let us suggest that this effect could be the result of either a direct effect of MMA on testosterone levels (as shown in our first study), or through its possible action on other organs involved in testosterone metabolism and seminal vesicle trophicity such as the hypophysis.