Neuroprotective role of delta opioid receptors in hypoxic preconditioning

Background/aim

The purpose of the present study was to explore the neuroprotective role of delta opioid receptors (DOR) in the rat cortex in hypoxic preconditioning.

Materials and methods

Rats were randomly divided into 8 groups: control (C), sham (S), hypoxic preconditioning (PC), severe hypoxia (SH), PC + SH, PC + SH + Saline (PS), PC + SH + DPDPE (DPDPE, selective DOR agonist), PC + SH + NT (NT, Naltrindole, selective DOR antagonist). Drugs were administered intracerebroventrically. Twenty four h after the end of 3 consecutive days of PC (10% O2, 2 h/day), the rats were subjected to severe hypoxia (7% O2 for 3 h). Bcl-2 and cyt-c were measured by western blot, and caspase-3 was observed immunohistochemically.

Results

Bcl-2 expressions in the PC group were higher than in control, SH, and PC + SH groups. Even though there were no significant differences between the groups in terms of cyt-c levels, caspase-3 immunoreactivity of cortical neurons and glial cells in the severe hypoxia and NT groups were higher than in the control, sham, and hypoxic preconditioning groups. DPDPE administration diminished caspase-3 immunoreactivity compared with all of the severe hypoxia groups.

Conclusions

These results suggest that cortical cells are resistant to apoptosis via increased expression of Bcl-2 and decreased immunoreactivity of caspase-3 in the cortex, and that DOR is involved in neuroprotection induced by hypoxic preconditioning via the caspase-3 pathway in cortical neurons.

Is leptin receptor expression triggered in the case of embryo transfer to endometrium coculture?

Background/aim

A synchronized dialogue between maternal and embryonic tissues is required for successful implantation. Low uterine receptivity is responsible for two-thirds of implantation failures and leptin is effective in the physiology of reproduction by binding to specific receptors. In this study, we investigate leptin receptor expression in cases of embryo transfer to endometrial coculture.

Materials and methods

Biopsy materials were taken from 20 females with indication for coculture application and were cultured in an appropriate medium after the epithelial cells were isolated. The grown cells were cultured in chamber slides as the first group. For the second group, day 3 embryo was added to chamber slides and the development was observed. The embryo was transferred 1 or 2 days later and other cells (after the transfer process) were used to form the second group. After fixation, immunohistochemical staining was performed with anti-leptin primary antibody.

Results

Regarding the coculture without embryo transfer, moderate leptin receptor immunoreactivity was seen in the perinuclear region and the cell membrane. Also, regarding the coculture with embryo transfer, moderate leptin receptor immunoreactivity was seen in the cytoplasm and strong leptin receptor immunoreactivity was seen in the cell membrane.

Conclusion

Embryo transfer to endometrium coculture triggers leptin receptor expression.

The Effects of Riluzole on Cisplatin-induced Ototoxicity

Introduction  Riluzole (2-amino-6-trifluoromethoxy benzothiazole) is known as a neuroprotective, antioxidant, antiapoptotic agent. It may have beneficial effects on neuronal cell death due to cisplatin-induced ototoxicity.

Objective  To evaluate the effect of riluzole on cisplatin-induced ototoxicity in guinea pigs.

Methods  Twenty-four guinea pigs, studied in three groups, underwent auditory brainstem response evaluation using click and 8 kHz tone burst stimuli. Subsequently, 5 mg/kg of cisplatin were administered to all animals for 3 days intraperitoneally (i.p.) to induce ototoxicity. Half an hour prior to cisplatin, groups 1, 2 and 3 received 2 ml of saline i.p., 6 mg/kg of riluzole hydrochloride i.p., and 8 mg/kg of riluzole hydrochloride i.p., respectively, for 3 days. The auditory brainstem responses were repeated 24 hours after the last drug administration. The cochleae were analyzed by transmission electron microscopy (TEM).

Results  After drug administiration, for 8,000 Hz stimulus, group 1 had significantly higher threshold shifts when compared with groups 2 ( p  < 0.05) and 3 ( p  < 0.05), and there was no significant difference in threshold shifts between groups 2 and 3 ( p  > 0.05). Transmission electron microscopy findings demonstrated the protective effect of riluzole on the hair cells and the stria vascularis, especially in the group treated with 8 mg/kg of riluzole hydrochloride.

Conclusion  We can say that riluzole may have a protective effect on cisplatin- induced ototoxicity. However, additional studies are needed to confirm these results and the mechanisms of action of riluzole.

Comparison of hippocampal interleukin-6 immunoreactivity after exhaustive exercise in both exercise-trained and untrained rats

BACKGROUND/AIM

Exhaustive exercise is a strong stress factor and can impact cytokine production in the brain. Interleukin-6 (IL-6) is produced in greater amounts than any other cytokine in response to exercise, and its effects are closely related to both exercise duration and intensity. In this study, we measured the differences between the amount of IL-6 reactivity of the hippocampus after an exhaustive session ofrunning in long-term exercise-trained and untrained rats.

MATERIALS AND METHODS

The exercise-trained group ran on a treadmill for 12 weeks. Both groups were forced to run until exhaustion. Each group of rats was sacrificed immediately, 1 day, or 3 days after exhaustion and the brains were evaluated for IL-6 immunoreactivity in the hippocampus.

RESULTS

Hippocampal IL-6 immunoreactivity was absent in controls, mild to severe in untrained rats, and weak to mild in long-term-trained rats. The most prominent increase in IL-6 was observed in the untrained rats sacrificed 1 day after exhaustion.

CONCLUSION

Exercise to exhaustion resulted in increased IL-6 levels in brain slices in both groups of rats, but long-term exercise training protected the hippocampus from exposure to an extreme increase in IL-6. The immediate effects of these cytokine levels were observed 1 day after exhaustion.

Effects of hyperglycemia on the developing brain in newborns

BACKGROUND

Hyperglycemia is a common problem in preterm neonates and is associated with increased risk of mortality and severe morbidities such as brain damage. However, available data about the effects of severity of hyperglycemia on the developing brain in the early life is limited. Therefore, we evaluated the effects of moderate and severe hyperglycemia on the developing brain.

METHOD

Thirty newborn Sprague-Dawley rats were randomly divided into three groups as control, moderate hyperglycemia (30% dextrose), and severe hyperglycemia (50% dextrose). Pups in the hyperglycemia groups were administered subcutaneous sterile dextrose solution at a dose of 4 mL/kg daily from the second day to the eleventh day of life. Blood glucose levels were measured every day in all study groups. Rat brain tissues were removed at the end of the study. Histopathologic and immunohistochemical (caspase-9, -8, and -3) examination and biochemical analysis including xanthine oxidase, total antioxidant status, total oxidant status, and malondialdehyde activities were performed.

RESULTS

Weight of the brain tissues in rats with hyperglycemia groups was significantly lower than the control group (P < 0.05). Weight of the brain tissues in rats with moderate hyperglycemia was lower than that of the severe hyperglycemia (P < 0.05). In the histopathologic and immunochemical evaluation, severity of brain damage and apoptosis were significantly higher in the severe hyperglycemia group, especially at the level of the hippocampus (P < 0.05). Tissue malondialdehyde, xanthine oxidase levels, and total oxidant status were significantly increased in the severe hyperglycemia group, whereas total antioxidant status was significantly decreased in the severe hyperglycemia group (P < 0.001).

CONCLUSION

Brain damaging effects of severe hyperglycemia were observed in the developing brains of the rat pups. It might be inferred that severe hyperglycemia can damage the developing brain especially in preterm infants.

[Is bone microstructure different between osteopenic and osteoporotic patients with femoral neck fracture?]

OBJECTIVES

This study aims to investigate whether bone microstructure is different between osteopenic and osteoporotic patients with femoral neck fracture.

PATIENTS AND METHODS

Fourteen patients (5 males, 9 females) with proximal femoral fracture following low energy trauma were included in the study. Patients with secondary osteoporosis and who received antiosteoporotic treatment prior to trauma were excluded. The patients were divided into two groups based on the bone mineral density measurement, including osteopenic group (n=7, mean age 69 years; range 63-74 years) and osteoporotic group (n=7, mean age 74.1 years; range 67-78 years). Cortical bone specimens for biopsy obtained from the patients who underwent endoprosthesis during partial hip arthroplasty and were evaluated using light microscope.

RESULTS

Mean cortical bone thickness was 3622.14 μM in osteopenic group, and 2323.14 μM in osteoporotic group (p<0.005). However, light microscope revealed similar characteristics for both groups.

CONCLUSION

Although a significant difference was found between the groups in terms of cortical thickness, bone microstructure showed similar characteristics in osteopenic and osteoporotic patients with low energy femoral neck fracture.

[Age-related changes in light microscopy with Sirius red technique in rat Achilles tendon]

OBJECTIVES

In this study, age-related morphological changes in intact rat Achilles tendon was investigated.

MATERIALS AND METHODS

Thirty Wistar albino rats of 2-3 weeks, six months and 12 months old groups 10 animal in each group were examined with Sirius red light microscobic staining.

RESULTS

The Sirius red light microscobic staining revealed that red stained collagen fibers have a decreased waviness with more rounded appearence of tenocyte nuclei, extracellular matrix along a increased vascularity and the number of tenocytes decreased with age was statistically meaningfull.

CONCLUSION

The possible causes of the spontaneously Achilles tendon rupture in adult ages group was investigated with Sirius red light microscopic technique. In this age group, initiation of the degenerative changes are decreasing the elasticity thus function of this tendon.