Classification, location, and intensity of granules in retinal pigment epithelium following sodium iodate injection in rat animal model

Objectives

Age-related macular degeneration (AMD) is one of the eye diseases that can affect a person's central vision. Retinal pigment epithelium (RPE) cells are damaged in this medical condition and some pigments are presented in these cells. Here, we aimed to investigate melanin and lipofuscin granules of RPE cells as a precursor of AMD.

Materials and Methods

Hooded rats (n=18) were divided into two groups and received 100 μl of sodium iodate (SI) into the retro-orbital sinus of their eyes at 40 and 60 mg/kg doses. The total number of melanin and lipofuscin granules, different types of granules, cytoplasmic dispersion of granules as well as morphological changes in the shape and number of nuclei of RPE cells were evaluated over the course of 1-30 days.

Results

The total number of melanin pigments increases over time at a dose of 40 mg/kg and decreases at a dose of 60 mg/kg. Also, the total number of lipofuscin granules in 40 mg/kg increases over time and decreases in 60 mg/kg. Autofluorescent intensity (AF) is also increased at 40 mg/kg, but at 60 mg/kg, the highest intensity is on day 7. Also, the highest number of multinucleated giant cells was on day 7 at 60 mg/kg and the most changes in cell appearance due to sodium iodate injection were seen on the first day after injection.

Conclusion

We demonstrated that granules and autofluorescent intensity appear to decrease at high doses of sodium iodate, which is similar to the advanced stage of the AMD disease, where the number of granules and AF intensity increase in the middle and even early stages of the disease.

Maternal aerobic running during mid or late gestation improves the quality of oogenesis and folliculogenesis in the ovary of neonatal rats: An experimental study

Background

Regular maternal exercise in pregnancy enhances the physiological, metabolic, and psychological health of mother and fetus.

Objective

To determine the effect of maternal aerobic running during mid or late gestation on plasma levels of estrogen and progesterone and the histological alterations in the ovary of neonatal rats.

Materials and Methods

Twenty-one female Wistar rats were randomly divided into experimental groups to exercises during the 2 nd or 3 rd wk of pregnancy (n = 14) and a control group (n = 7). After birth, the neonate's blood was obtained and the estrogen and progesterone levels were evaluated. The ovaries were then removed and used for histological investigations and apoptic assessment.

Results

Higher concentrations of estrogen and progesterone were found in the neonates of the experimental groups (p = 0.001) compared to the control group. The experimental groups had a large ovarian diameter (2 nd wk: p = 0.044; 3 rd wk: p = 0.005) and angiogenesis (2 nd wk: p = 0.003; 3 rd wk: p = 0.001). In addition, significant enhancements were seen in the the experimental groups in terms of the number (2 nd wk: p = 0.017; p = 0.035) and diameter (2 nd wk: p = 0.046; 3 rd wk: p = 0.004) of primordial follicles, as well as in the diameter of primary oocytes (2 nd wk: p = 0.073; 3 rd wk: p = 0.019) compared to the control group. Moreover, rats that exercised had a lower number of apoptotic primordial follicles than the control group (2 nd wk: p = 0.001; 3 rd wk: p = 0.001).

Conclusion

It was shown that maternal aerobic running can lead to increased plasma levels of estrogen and progesterone, also improved histological characteristics of the ovary in neonatal rats.

Neurosphere-Free Transdifferentiation of Rat Bone Marrow Stromal Stem Cells Into Retinal Cells and Retinal Pigment Epithelium

Introduction:

Neurosphere-free transdifferentiation of bone marrow stem cells into Retinal Pigment Epithelium (RPE) and Retinal Cells (RCs) in vitro could offer an exceptional opportunity to study cell replacement in degenerative eye diseases. Thus, a simple and efficient protocol for retinal cells production from transdifferentiation of rat BMSCs in the neurosphere-free state is reported.

Methods:

Extracted BMSCs from hooded pigment rats were exposed to a single-step protocol, including neurosphere-free, containing a cocktail medium that induced transdifferentiation into Retinal Pigment Epithelium (RPE) and retinal cells.

Results:

The results showed morphological differentiation changes in vitro. Also, the expressed retinal pigment epithelium and retinal cell markers, such as retinal orthodenticle homeobox 2 (23.45%), retinal pigment epithelium protein 65 (91.54%), cellular retinaldehyde-binding protein (91.21%), vascular endothelial growth factor (94.79%), rhodopsin (57.19%), glial fibrillary acidic protein (28.33%), and neurofilament 200 (24.55%).

Conclusion:

Overall, these findings showed that a protocol without using basic fibroblast growth factor, epidermal growth factor, and B-27 supplements could generate RPE and retinal cells in vitro.

Protective effects of morphine in a rat model of post-traumatic stress disorder: Role of hypothalamic-pituitary-adrenal axis and beta- adrenergic system

Post-traumatic stress disorder (PTSD) arises after tremendous traumatic experiences. Recently, we have reported that morphine has time-dependent protective effects against behavioral and morphological deficits in the single prolonged stress (SPS) as an experimental model of PTSD in adult male rats. To find the mechanisms underlying the protective effects of morphine against SPS-induced PTSD-like symptoms, the present study investigated the interaction between morphine and hypothalamic-pituitary-adrenal (HPA) axis and beta - adrenergic system, which crucially involved in the stress response, on PTSD-like symptoms in male rats. The animals were exposed to the SPS procedure (restraint for 2 h, forced swimming for 20 min, and ether anesthesia) and morphine (10 mg/kg) or saline was injected 24 h following the SPS. The glucocorticoid receptor antagonist RU486 (20 mg/kg), the mineralocorticoid receptor antagonist spironolactone (50 mg/kg), and the corticosterone synthesis inhibitor metyrapone (50 mg/kg) were injected 90 min before morphine administration to block the HPA axis activity. The beta - adrenergic receptor blocker propranolol (10 mg/kg) and the peripheral beta-adrenergic receptor blocker nadolol (5 mg/kg) were administered 30 min before morphine injection to block the beta - adrenergic system. Anxiety-like behaviors were evaluated using the elevated plus maze (EPM) 11 days after the SPS. After that, animals were conditioned in a fear-conditioning task and extinction training was performed on days 1, 2, 3, 4 and 11 after fear conditioning. SPS increased anxiety-like behaviors and impaired fear extinction. Morphine injection 24 h after SPS significantly improved anxiety-like behaviors and enhanced fear extinction. The RU486, spironolactone and metyrapone prevented the protective effects of morphine on both SPS-induced anxiety-like behaviors and impaired fear extinction. The propranolol, and nadolol did not prevent the effect of morphine on anxiety-like behaviors, but the propranolol prevented morphine effects on fear extinction in SPS animals. These findings together suggest that the protective effects of morphine on PTSD-like symptoms in rats require a certain level of the HPA axis and central beta - adrenergic activity and any alteration in the function of these systems can impede the protective effects of morphine.

Effects of Amoxicillin on the Structure and Mineralization of Dental Enamel and Dentin in Wistar Rats

Objectives:

The development of teeth is affected by genetic and environmental factors. Amoxicillin is a widely prescribed semi-synthetic antibiotic. Its most frequent side effects are gastrointestinal disorders and hypersensitivity reactions. The purpose of this study was to determine the effect produced by amoxicillin administration on dental enamel and dentin in Wistar rats.

Materials and Methods:

Twelve pregnant adult Wistar rats were equally divided into four different groups. Negative controls were prescribed with a saline solution. Positive controls were prescribed with tetracycline (130 mg/kg). The other two groups were treated with amoxicillin doses of 50 and 100 mg/kg (every 8 hours), respectively. The treatments were daily administered by oral gavage from the 13th gestation day to the end of gestation. After birth, the offspring also received the same treatment as their mothers from day one to day twelve. After 24 hours, the newborns were sacrificed, the jaws were dissected, and the first molar teeth were collected. The samples were fixed in 10% formaldehyde solution and were histomorphologically and histopathologically observed to determine enamel and dentin abnormalities.

Results:

The mean ameloblastic layer thickness, enamel thickness, odontoblastic layer thickness, and dentin thickness were significantly different in the tetracycline group and the amoxicillin 50 and 100 mg/kg groups compared to the control group. Also, dentin hypomineralization and vacuolization of the odontoblastic layer were observed in the tetracycline- and amoxicillin-treated groups.

Conclusion:

This study showed that amoxicillin interferes with amelogenesis and dentinogenesis and reduces enamel and dentin thickness.

Interactive Effects of Exercise, Sex Hormones, and Transient Congenital Hypothyroidism on Long-Term Potentiation in Hippocampal Slices of Rat Offspring

Introduction:

The long-term adverse effects of transient thyroid function abnormalities at birth on intellectual development are proven. The effect of exercise increases in the presence of sex hormones. The current study aimed at investigating the possibility that a combination of sex hormones and exercise has synergistic effects on neural plasticity in Transient Congenital Hypothyroidism (TCH) rats.

Methods:

To induce hypothyroidism in the mothers, Propylthiouracil (PTU) was added to drinking water (100 mg/L) on the 6th day of gestation and continued until the 21^st Postnatal Day. From Postnatal Day (PND) 28 to 47, the female and male pups received 17β-estradiol and testosterone, respectively. The mild treadmill exercise began 30 minutes after the sex hormones or vehicle administration. On PND 48, electrophysiological experiments were performed on brain slices.

Results:

Increase of Long-Term Potentiation (LTP) was observed in sedentary-non-hormone female rats of TCH group, compared with that of the control. The exercise enhanced LTP in control rats, but the hormones showed no significant effect. The effect of exercise and sex hormone was not significant in the TCH group. The combination of exercise and testosterone enhanced LTP in TCH male rats, while the combination of exercise and estradiol or each of them individually did not produce such an effect on LTP in TCH female rats.

Conclusion:

The study findings showed an increase in excitatory transmission despite the returning of thyroid hormone levels to normal range in TCH female rats. Also a combination treatment including exercise and testosterone enhanced LTP in male rats of TCH group, which was a gender-specific event.

The effects of propolis extract on ovarian tissue and oxidative stress in rats with maternal separation stress

BACKGROUND

Stress in infancy has dramatic effects on different systems, including the nervous system, endocrine, immune, reproductive and etc.

OBJECTIVE

The purpose of this study was to investigate the effects of extract of Iranian propolis (EIP) on ovarian tissue and oxidative stress in rats with maternal separation stress.

MATERIALS AND METHODS

48 immature female rats were divided randomly into six groups. 1) Control group, 2) Control group+saline, 3) Stress group, includes infants that were separated from their mothers 6 hr/day, the 4th, 5th and 6th groups consisted of infants who in addition to daily stress received 50, 100 and 200 mg/kg of EIP, respectively. Then serum corticosterone, 17-beta-estradiol, malondialdehyde, total superoxide dismutase, glutathione peroxidase and ferric reducing antioxidant power levels were measured. The ovarian sections were stained by H&E, PAS, and TUNEL methods and were studied with optical microscopy.

RESULTS

Stress increased the blood serum corticosterone levels and 17-beta-estradiol reduced significantly (p<0.001) and EIP prevented from this changes (p<0.01). EIP significantly increased the number of ovarian follicles, oocytes and oocytes diameter in neonatal rat following stress (p<0.01). EIP also significantly decreased the number of atretic follicles, TUNEL+granulosa cells, malondialdehyde levels and increased ferric reducing antioxidant power, total superoxide dismutase and glutathione peroxidase serum levels in neonatal rats following stress. The dose of 200 mg/kg EIP was more effective.

CONCLUSION

This Study showed that the Iranian Propolis significantly could prevent oxidative stress and histopathological changes in the ovary of the neonatal rat the following stress.

The Effect of Co-administration of 4-Methylcatechol and Progesterone on Sciatic Nerve Function and Neurohistological Alterations in Streptozotocin-Induced Diabetic Neuropathy in Rats

OBJECTIVE

Diabetic neuropathy is the most common complication of diabetes mellitus affecting the nervous system. In this study, we investigated the in vivo effects of combined administration of 4-methylcatechol (4-MC) and progesterone (P) as a potential therapeutic tool for sciatic nerve function improvement and its role in histomorphological alterations in diabetic neuropathy in rats.

MATERIALS AND METHODS

Male adult rats were divided into 3 groups: sham operated control (CO), untreated diabetic (DM) and diabetic treated with progesterone and 4-methylcatechol (DMP4MC) groups. Diabetes was induced by a single dose injection of 55 mg/ kg streptozotocin (STZ). Four weeks after the STZ administration, the DMP4MC group was treated with P and 4-MC for 6 weeks. Then, following anesthesia, the animals' sciatic nerves were removed and processed for light and transmission electron microscopy (TEM) as well as histological evaluation.

RESULTS

Diabetic rats showed a statistically significant reduction in motor nerve conduction velocity (MNCV), nerve blood flow (NBF), mean myelinated fiber (MF) diameters and myelin sheath thickness of the sciatic nerve after 10 weeks. In the sciatic nerve of the untreated diabetic group, endoneurial edema and increased number of myelinated fibers with myelin abnormalities such as infolding into the axoplasm, irregularity of fibers and alteration in myelin compaction were also observed. Treatment of diabetic rats with a combination of P and 4-MC significantly increased MNCV and NBF and prevented endoneurial edema and all myelin abnormalities.

CONCLUSION

Our findings indicated that co-administration of P and 4-MC may prevent sciatic nerve dysfunction and histomorphological alterations in experimental diabetic neuropathy.