The effect of acute and chronic formaldehyde exposure on learning and memory in male and female rats.

AIM: Formaldehyde is a chemical that lies behind the various systemical failures in organism. 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. MATERIALS AND METHODS: 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. TUNEL staining was used to identify apoptosis in the brains obtained after decapitation. RESULTS: 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.

Effects of electroacupuncture at ST36 and BL20 on the diabetic rat testis.

OBJECTIVE: We aimed to evaluate the effects of electroacupuncture (EA) at ST36 and BL20 on the testicular tissues in a rat model of diabetes and to explore the mechanisms of action. METHODS: A total of 34 male Sprague-Dawley rats were allocated to a control group (n = 10), diabetes (D) group (n = 12) or diabetes + acupuncture (DA) group (n = 12). To model diabetes, rats in groups D and DA received an intraperitoneal injection of a single dose of 35 mg/kg streptozotocin (STZ) dissolved in citrate buffer (pH = 4.5; 0.1 M) after 2 weeks of high-fat diet administration. Under xylazine/ketamine anesthesia, stainless steel needles (30 mm × 0.25 mm) were inserted bilaterally at ST36 and BL20. The needles were connected to an EA device via cables, and EA was applied for 30 min (15 Hz frequency and 0.2-1 mA intensity) twice a week for 5 weeks. RESULTS: The effects of EA at ST36 and BL20 on blood glucose levels and body weight, biochemical parameters, histopathological, morphometric and immunohistochemical findings, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis were evaluated. A significant decrease was detected in DA versus D groups in blood glucose levels, basement membrane thickness and apoptotic cell/tubule indices. In addition, there was a significant increase in the Johnsen scores, seminiferous tubule diameters, serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone, proliferation indices, and sex hormone-binding globulin (SHBG) and insulin-like peptide 3 (INSL3) immunoreactivities. CONCLUSION: EA had multiple positive effects on blood glucose homeostasis and testicular structure/function in this rat model of diabetes. EA may be effective at preventing or eliminating histopathological damage in the diabetic testis.

Does Hypochlorous Acid Cause Ototoxicity? An Experimental Study.

AIM: Hypochlorous acid (HOCl) is a weak acid that ionizes in water. It is an effective antiseptic exhibiting low toxicity on living tissues. We aimed to investigate the ototoxic effects of HOCl on an animal model by using electrophysiological and histological methods. MATERIALS AND METHODS: The study comprised 32 Sprague-Dawley rats, which were separated into four groups: control group (A), saline solution group (B), 70% isopropyl alcohol + 2% chlorhexidine group (C), and HOCl group (D). After recording the auditory brainstem response (ABR) for basal hearing thresholds (8, 16, 24, and 32 kHz), 0.03 ml of the aforementioned materials was injected intratympanically three times every 2 days in groups B, C, and D. ABR measurements were repeated on the 7th and 21st days. All animals were sacrificed, and temporal bones were prepared for examinations of cochlear histology and vascular endothelial growth factor immunohistochemistry. RESULTS: Basal hearing levels were normal across all frequencies and groups, with no statistical differentiation. On the 7th and 21st days after the ABR test, all other groups demonstrated a significant deterioration in hearing levels compared with group A. When the results from 7th and 21st days were compared within group D, a partial recovery was observed. In histopathology, groups C and D demonstrated moderate and severe cochlear degeneration, along with decreased immunoreactivity in the organ of Corti, stria vascularis, and spiral ligament. CONCLUSION: This is the first study to evaluate the safety of using HOCl in otology. Although HOCI is less ototoxic than the disinfectant used, it may have a toxic effect on cochlea.Level of Evidence: Animal Research.

Role of JNK, TGF-ß1, Akt, IL-1ß and INSL-3 in proanthocyanidin protection against apoptosis in diabetic rat testis.

We investigated how proanthocyanidin treatment altered c-Jun N-terminal kinases, transforming growth factor beta 1, serine/threonine-specific protein kinase, interleukin 1 beta and insulin-like 3 expression in the testis of diabetic rats. We used 24 Wistar albino male rats divided into four groups. Group 1 was untreated control. Group 2 was treated with 40 mg/kg streptozotocin (STZ) for 5 days. Group 3 was treated with 40 mg/kg STZ + 250 mg/kg proanthocyanidin once daily for six weeks. Group 4 was treated with 40 mg/kg STZ + 250 mg/kg proanthocyanidin. Superoxide dismutase activity was reduced in groups 3 and 4 compared to group 2. Glutathione peroxidase activity was increased significantly in groups 3 and 4 compared to groups 1 and 2. Catalase activity was decreased in group 4 compared to group 2. We found that proanthocyanidin increased cell proliferation in diabetic testis. Phospho-JNK and TGF-ß1 immunostaining was decreased groups 3 and 4 compared to group 2, while p-Akt immunostaining was increased in groups 3 and 4. The number of IL-1ß immunostained cells in groups 3 and 4 was decreased compared to group 2. INSL-3 immunostaining was increased significantly in group 3 compared to group 2. Our findings indicate that proanthocyanidin ameliorated diabetes related testicular dysfunction. Proanthocyanidin contributes to a balanced oxidant-antioxidant status, and balanced proliferation and apoptosis activity in the germinal cells.

Does Oral Monosodium Glutamate Have a Cochleotoxic Effect? An Experimental Study.

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.

Sitagliptin and fucoidan prevent apoptosis and reducing ER stress in diabetic rat testes.

Sitagliptin increases the levels of incretin hormones and stimulates a decrease in blood glucose levels, by blocking the DPP4 enzyme. We have very limited information about impact of sitagliptin on male genital system and relationship between sitagliptin/diabetes/ER. Fucoidan can be effective in blood glucose homeostasis. We goal to explain of the effect of sitagliptin and introduce an approach of fucoidan treatment in experimental diabetes in male rats. Fifty-eight Wistar albino rats were divided into C-control group and D-diabetes group: 60 mg/kg streptozotocin intraperitoneal (i.p.); DS group: STZ + 10 mg/kg sitagliptin intragastric (i.g.); DF group: STZ + 100 mg/kg fucoidan i.p.; and DSF group: STZ + 10 mg/kg sitagliptin + 100 mg/kg fucoidan. A significant decrease was detected when DS, DF and DSF groups compared to group D in blood glucose levels, basement membrane thickness and also apoptotic cell/tubule index, pJNK, caspase 3, caspase 12, GRP78, CHOP and DPP4. Sitagliptin and fucoidan have been found to be effective in blood glucose homeostasis and reducing the expression of certain proteins that lead to apoptosis and especially the proteins in the ER stress pathway. Therefore, we think that both sitagliptin and fucoidan can be effective in preventing or eliminating histopathological damages in diabetic testicular tissues, and their treatment effects can be used more.