Key words: Diabetes mellitus; Mitogen-Activated Protein Kinases; Extracellular Signal-Regulated Kinases; JNK Mitogen-Activated Protein Kinases; Streptozocin; Testes; Rats

Formaldehyde is a chemical that can cause various disorders when it enters metabolism. Many products that people use contain formaldehyde. Owing to its tissue fixative properties, scientists who work in life sciences are exposed to this substance more than others. Several studies have shown that formaldehyde affects the CA1 and CA3 regions of the hippocampus, which play crucial roles in memory consolidation. In this study, we aimed to investigate anxiety levels and indicate the short and long term effects of formaldehyde and sex-related differences by exposing formaldehyde to male and female rats. Formaldehyde (10 mg/kg) was administered intraperitoneally for 7 days for acute exposure and 30 days for chronic exposure. Cognitive assessment was performed using fear conditioning, elevated plus maze, and Morris water maze tests. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining was used to identify apoptosis in the brains obtained after decapitation. Exposure to intraperitoneal formaldehyde does not impair learning and memory in acute and chronic periods and has no effect on depression or anxiety. After acute exposure, apoptosis was observed in the hippocampal CA1 and CA3 regions in males. When the cognitive test results were examined, no differences were found between the experimental and control groups. There was also no significant difference between males and females.

Diabetic male infertility/subfertility is an important complication of diabetes. The molecular mechanisms responsible for this complication have not been thoroughly investigated. We aimed to elucidate the role of KU70, SIRT1, and SIRT6 proteins in diabetic testis. Sprague–Dawley male rats were maintained under stable laboratory conditions. The rats were divided into a control group (n=8) and a diabetes group (n=8 treated with a single dose of 50 mg/kg streptozotocin). At the end of the 1-month experimental period, animals were sacrificed under anesthesia. Both testicles were removed, processed lightly, and studied through electron transmission microscopy and western blotting. Blood samples were collected for biochemical analysis. Histopathological analysis revealed that, in the diabetes group, the diaphragmatic tubule diameters and serum testosterone levels were decreased. KU70 immunoreactivity was statistically significantly increased, whereas SIRT1 and SIRT6 expression was significantly decreased compared with that observed in the control group. This is the first study to examine the expression of KU70, SIRT1, and SIRT6 in diabetic testicular tissue for the first time. According to the results, KU70, SIRT1, and SIRT6 may play an important role in cell apoptosis in diabetic testicular tissue. Importance of these proteins should be investigated further in additional quantitative studies.

Introduction: The effect of orally consumed monosodium glutamate (MSG), which is a common additive in the food industry, on the cochlea has not been investigated. The present study aimed to investigate the possible cochleotoxic effects of oral MSG in guinea pigs using electrophysiological, biochemical, and histopathological methods. Methods: Thirty guinea pigs were equally divided into control and intervention groups (MSG 100 mg/kg/day; MSG 300 mg/kg/day). At 1 month, 5 guinea pigs from each group were sacrificed; the rest were observed for another month. Electrophysiological measurements (distortion product otoacoustic emission [DPOAE] and auditory brainstem response [ABR]), glutamate levels in the perilymph and blood samples, and histopathological examinations were evaluated at 1 and 2 months. Results: Change in signal-to-noise ratio at 2 months was significantly different in the MSG 300 group at 0.75 kHz and 2 kHz (p = 0.013 and p = 0.044, respectively). There was no statistically significant difference in ABR wave latencies of the guinea pigs given MSG compared to the control group after 1 and 2 months; an increase was noted in ABR thresholds, although the difference was not statistically significant. In the MSG groups, moderate-to-severe degeneration and cell loss in outer hair cells, support cells, and spiral ganglia, lateral surface junction irregularities, adhesions in stereocilia, and partial loss of outer hair cell stereocilia were noted. Conclusion: MSG, administered in guinea pigs at a commonly utilized quantity and route of administration in humans, may be cochleotoxic.