Neuroanatomical changes of the medial prefrontal cortex of male pups of Wistar rat after prenatal and postnatal noise stress.

Recent evidences showed that, noise stress causes abnormal changes in structure and function of central nervous system (CNS). The Current study was conducted to evaluate some stereological parameters of the medial prefrontal cortex (mPFC) of male pups of Wistar rat after prenatal and early postnatal noise stress. 18 pregnant Wistar rats were randomly divided into prenatal noise-exposed (NE) group, postnatal NE group, and controls. Male pups of NE groups were exposed to noise 100 dB at the frequency ranges of 500-8000 Hz, 4 h per day from gestational day one (GD1) to GD21 for the prenatal NE group, and from postnatal day one (PND1) to PND21 in the postnatal NE group. The Control group animals were maintained under standard condition without noise stimulation. Corticosterone level in plasma was measured using ELISA technique. Changes of the neurons and non-neurons cells number and volume of the mPFC were evaluated by stereological analysis. Tunnel assay was also used for detection of apoptotic cells. Increase in plasma corticosterone level, decrease in the number of neurons, and increase in the apoptotic cells number were observed in both NE groups. Decrease in volume of mPFC and also in non-neurons cells number was observed in the prenatal NE group. An increase in the non-neurons number was seen in the postnatal NE group. Data of the current comparative study showed that, noise stress during prenatal and early postnatal periods can induce the abnormal alteration in some stereological parameters of mPFC in male pups of Wistar rat. These negative alterations were more remarkable after prenatal noise stress.

Reconstruction of mandibular defects using synthetic octacalcium phosphate combined with bone matrix gelatin in rat model.

BACKGROUND: Regeneration of bone defects remains a challenge for maxillofacial surgeons. The objective of this study was to assess the osteogenic potential of octacalcium phosphate (OCP) and bone matrix gelatin (BMG) alone and in combination with together in artificially created mandibular bone defects. MATERIALS AND METHODS: In this experimental study Forty-eight male Sprague-Dawley rats (6-8 weeks old) were randomly divided into four groups. Defects were created in the mandible of rats and filled with 10 mg of OCP, BMG, or a combination of both (1/4 ratio). Defects were left unfilled in the control group. To assess bone regeneration and determine the amount of the newly formed bone, specimens were harvested at 7, 14, 21, and 56 days postimplantation. The specimens were processed routinely and studied histologically and histomorphometrically using the light microscope and eyepiece graticule. The amount of newly formed bone was quantitatively measured using histomorphometric methods. Histomorphometric data were analyzed using SPSS software. Mean, standard deviation, mode, and medians were calculated. Tukey HSD test was used to compare the means in all groups. P < 0.05 was considered as statistically significant (i.e., 5% significant level). RESULTS: In the experimental groups, the new bone formation was initiated from the margin of defects during the 7-14 days after implantation. By the end of study, the amount of newly formed bone increased and relatively matured, and almost all of the implanted materials were absorbed. In the control group, slight amount of new bone had been formed at the defect margins (next to the host bone) on day 56. The histomorphometric analysis revealed statistically significant differences in the amount of newly formed bone between the experimental and the control groups (P < 0.001). CONCLUSION: Combination of OCP/BMG may serve as an optimal biomaterial for the treatment of mandibular bone defects.

Octacalcium phosphate/gelatin composite facilitates bone regeneration of critical-sized mandibular defects in rats: A quantitative study.

Background. Regeneration of bone defects remains a challenge for maxillofacial surgeons. The present study aimed to compare the effects of octacalcium phosphate (OCP) and the combination of octacalcium phosphate/gelatin (OCP/Gel) on mandibular bone regeneration in rats Methods. In the present study, 36 male Sprague-Dawley rats were used. The animals were randomly assigned to the following experimental groups: OCP (n=12), OCP/Gel (n=12), and the control group (n=12). Defects were created in the rat mandibles and filled with 10 mg of OCP and OCP/Gel disks in the experimental groups. In the control group, however, no substance was administered. Samples were taken on days 7, 14, 21 and 56, respectively, after the implantation. Sections (5 µ) were prepared and stained by H&E. The sections were studied, and the volume fraction of newly formed bone was measured by Dunnett's T3 test based on the significance level (P=0.05). Results. In the experimental groups, the new bone formation began from the margin of defects 7‒14 days after the implantation. During the healing process, the newly formed bone healed a larger area of the defects and grew structurally. In the control group, the defects were primarily filled with dense connective tissue, and only a small amount of new bone was formed. The present study showed a statistically significant difference in the volume of newly formed bone between the experimental groups and the control group (P<0.001). Conclusion. OCP/Gel composite can be beneficial in the healing process of mandibular bone defects.