Neonatal exposure to monosodium glutamate induces morphological alterations in suprachiasmatic nucleus of adult rat.

Neonatal exposure to monosodium glutamate (MSG) induces circadian disorders in several physiological and behavioural processes regulated by the suprachiasmatic nucleus (SCN). The objective of this study was to evaluate the effects of neonatal exposure to MSG on locomotor activity, and on morphology, cellular density and expression of proteins, as evaluated by optical density (OD), of vasopressin (VP)-, vasoactive intestinal polypeptide (VIP)- and glial fibrillary acidic protein (GFAP)-immunoreactive cells in the SCN. Male Wistar rats were used: the MSG group was subcutaneously treated from 3 to 10 days of age with 3.5 mg/g/day. Locomotor activity was evaluated at 90 days of age using 'open-field' test, and the brains were processed for immunohistochemical studies. MSG exposure induced a significant decrease in locomotor activity. VP- and VIP-immunoreactive neuronal densities showed a significant decrease, while the somatic OD showed an increase. Major axes and somatic area were significantly increased in VIP neurons. The cellular and optical densities of GFAP-immunoreactive sections of SCN were significantly increased. These results demonstrated that newborn exposure to MSG induced morphological alterations in SCN cells, an alteration that could be the basis for behavioural disorders observed in the animals.

Development of germ cell neoplasia in situ in chinchilla rabbits.

The present study was designed to describe the development of germ cell neoplasia in situ in Chinchilla rabbit by administration of estradiol. The study was performed in rabbits distributed into two groups: control and 17 ß-estradiol. The determination of histological alterations and POU5F1 and c-kit proteins employed as biomarkers for the diagnosis of this neoplasia was carried out. Testicular descent and complete spermatogenesis were observed in the control group. The protein biomarkers were negative. However, in the rabbits treated with estradiol, the testes remained undescended with the gonocytes undifferentiated to spermatogonia. There were histological lesions owing to germ cell neoplasia in situ and positive to POU5F1 and c-kit proteins. These findings indicate that the chinchilla rabbit is an ideal model to study this neoplasia in which the histological characteristics and biomarkers of the disease could be clearly observed. Using this model we suggested that the persisting gonocytes could be responsible for the development of germ cell neoplasia in situ.

Alterations induced by chronic lead exposure on the cells of circadian pacemaker of developing rats.

Lead (Pb) exposure alters the temporal organization of several physiological and behavioural processes in which the suprachiasmatic nucleus (SCN) of the hypothalamus plays a fundamental role. In this study, we evaluated the effects of chronic early Pb exposure (CePbe) on the morphology, cellular density and relative optical density (OD) in the cells of the SCN of male rats. Female Wistar rats were exposed during gestation and lactation to a Pb solution containing 320 ppm of Pb acetate through drinking water. After weaning, the pups were maintained with the same drinking water until sacrificed at 90 days of age. Pb levels in the blood, hypothalamus, hippocampus and prefrontal cortex were significantly increased in the experimental group. Chronic early Pb exposure induced a significant increase in the minor and major axes and somatic area of vasoactive intestinal polypeptide (VIP)- and vasopressin (VP)-immunoreactive neurons. The density of VIP-, VP- and glial fibrillary acidic protein (GFAP)-immunoreactive cells showed a significant decrease in the experimental group. OD analysis showed a significant increase in VIP neurons of the experimental group. The results showed that CePbe induced alterations in the cells of the SCN, as evidenced by modifications in soma morphology, cellular density and OD in circadian pacemaker cells. These findings provide a morphological and cellular basis for deficits in circadian rhythms documented in Pb-exposed animals.

Alterations in the spermatic function generated by obesity in rats.

In order to assess the effect of obesity on epididymal and germinal epithelia in control rats and obese rats induced by a high fat diet, we evaluated the epididymal and testicular morphologies, lipid peroxidation in the epididymis, leptin serum levels, steroid hormones, insulin, cholesterol, triglycerides, glycemia and some spermatobioscopic parameters. No significant difference was observed in the levels of insulin, glucose, cholesterol and triglycerides between the two groups. Nonetheless, in the obese rats, circulating leptin and estradiol levels showed a significant increase and there was a decline in the testosterone levels. The same group showed an increase in the lipid peroxidation of the epididymis and reduced spermatobioscopic parameters. The heads of the epididymis showed morphological differences in obese rats. No significant difference was observed between the testes of both groups. There is a clear evidence of an effect on sperm in obese rats and this seems to occur in the epididymis.