The influence of functional pinealectomy and exogenous melatonin application on healing of burr hole in adult rat calvaria: a histological and immunohistochemical study

Background: Even today, repair of the cranial defects still represents a significant challenge in neurosurgery and various options have been used for their reconstruction to date. but there are very few studies investigating the effects of exogenous administration of melatonin (MEL) as an agent that promotes bone regeneration. The goal of this study was to investigate the effects of functional pinealectomy (Px) and exogenous MEL administration on the bone repair properties and surrounding connective tissue alterations in a rat calvaria model. Materials and methods: The total of 30 adult female Wistar-Albino rats was randomly divided into three groups (n = 10): control (CO) group (12 h light/12 h dark exposure), functional Px group (24 h light exposure, light-induced functional Px), and Px+MEL group (light-induced Px plus MEL, 20 mg/kg/day for 12 weeks). Critical-sized burr-hole defects (diameter = 3.0 mm) were surgically created by a single operator in the calvarium of all rats, using an electric drill. Animals in Px+MEL group received MEL 20 mg/kg/day for 12 weeks. At the end of the study, bone healing and connective tissue alterations surrounding drilled defect area in the rat calvaria were determined in hematoxylin/eosin-stained and mallory azan slices applied in anti-bone sialoprotein (BSP). Image Pro Express 4.5 program was used for histomorphometric calculation of areas of new bone and fibrotic tissue. Normality control was performed by Shapiro Wilk test. Variance homogeneities were examined by Shapiro Wilk and Levene tests; Tukey HSD test was used as a post hoc method since there was no homogeneity problem. All hypothesis tests were performed at the 0.05 significance level. Results: Histological analysis showed that the bone repair process in the Px+MEL group was similar to that of the CO group, whereas the functional Px group showed a delay. Histomorphometrically, it was found that the Px group had the largest hole diameter and the most fibrotic scar area, although no binary statistical significance was found between the CO and Px+MEL groups (p=0.910). In terms of vascularization, it was observed that the most vascular structure was found in the Px+MEL group among the scar tissue and ossification areas, while the vascularization was the least in the Px group (p < 0.001). Conclusions: Our findings revealed that bone repair process was impaired in functional Px group, but exogenous MEL replacement was able to restore this response. Thus, it is concluded that utilization of MEL may improve the bone repair in calvarial defects

Melatonin Alters Age-Related Changes in Transcription Factors and Kinase Activation

Male mice were fed 40 ppm melatonin for 2 months prior to sacrifice at age 26 months, and compared with both 26 and 4 month-old untreated controls. The nuclear translocation of NF-κB increased with age in both brain and spleen and this was reversed by melatonin only in brain. Another transcription factor, AP-1 was increased with age in the spleen and not in brain and this could be blocked by melatonin treatment. The fraction of the active relative to the inactive form of several enabling kinases was compared. The proportion of activated ERK was elevated with age in brain and spleen but this change was unresponsive to melatonin. A similar age-related increase in glial fibrillary acidic protein (GFAP) was also refractory to melatonin treatment. The cerebral melatonin M1 receptor decreased with age in brain but increased in spleen. The potentially beneficial nature of melatonin for the preservation of brain function with aging was suggested by the finding that an age-related decline in cortical synaptophysin levels was prevented by dietary melatonin

Development and histology of the pineal gland in humans

The pineal gland is a photosensitive organ, an important timekeeper and regulator of the day/night cycle, called circadian rhythm. In humans, the pineal organ is located at the posterior wall of the third ventricle near to the center of the brain. It develops from neuroectoderm of the posterior portion of the roof of the diencephalon and remains attached to the brain by a short stalk. The pineal gland consists of several types of cells, principally pinealocytes and astrocytes. Histologically, pinealocytes have a slightly basophilic cytoplasm with large irregular or lobate nuclei and sharply defined nucleoli. When impregnated with silver salts, the pinealocytes appear to have long and tortuous branches reaching out to vascular connective tissue septa, where they end as flattened dilatations. These cells produce melatonin and some ill-defined pineal peptides. This chapter summarizes the embryonic development and histogenesis of the pineal gland, and defines the histological features of pinealocytes and astrocyte-like cells in the pineal gland, with particular reference to light and electron microscopical as well as immunohistochemical characteristics. © 2012 Nova Science Publishers, Inc. All rights reserved

Multiple morphological variations in a human mandible [Múltiples Variaciones Morfológicas en una Mandíbula Humana]

Bilateral mylohyoid bridging, hyperplasia of the coronoid process and bifid condylar process were detected in a human mandible. It is of great interest that such rare morphological anomalies can occur in the same mandible. Since sound understanding of the anatomical variations of the mandible, in conjunction with a careful pre-operative review of radiographs, are essential in the safe and complete performance of surgical and prosthetic rehabilitation, the authors of the present report believe that this case may add to the existing literature. © 2015, International Journal of Morphology. All rigthts reserved

Apoptosis in the development and pathophysiology of the limbic system [Limbik sistem gelişiminde ve fizyopatolojisinde apoptoz]

Limbic system is involved in the intangible functions of brain like emotions, inborn and acquired emotional responses, self-awareness, ability to understand intentions of others and and memory. Apoptosis has a critical role in the developing brain and disruption of developmental apoptosis may lead to neurodevelopmental disorders. This review summarizes apoptotic processes in the limbic system during fetal brain development in normal and pathological conditions and focuses on the molecular mechanisms of apoptosis

Development and histological features of cerebellum

Cerebellum is an organ attached to the brain stem at the back of the brain inside the skull. It coordinates body motion and harmonious muscle function; arranges learning and memory; and controls body balance. The cerebellum is anatomically divided into two parts: gray and white matters and it contains various types of cells histologically. Embryologically, there are some structural differences between the cerebellar cells of the histogenesis period and adult cerebellar cells, the first appear by the formation of cerebellar draft while the latter are formed during differentiation and maturation of the corresponding embryonic neuronal cells. In this chapter, the histological and embryological features of the cerebellum will be discussed in details with special reference on its neurofunctional connections. In particular, the chapter contains a variety of figures of cerebellar sections stained with histochemical and immunohistochemical techniques for a better understanding of the topic. © 2012 Nova Science Publishers, Inc

Influence of penicillin-induced epileptic activity during pregnancy on postnatal hippocampal nestin expression in rats: Light and electron microscopic observations

PubMed ID: 15290185Objects: Current data concerning the effects of maternal epileptic phenomena on newborns are limited. In clinical practice, therefore, it is difficult to suggest proper guidelines on this issue. This study was carried out to investigate the morphological changes in the hippocampus of newborn pups of rats subjected to experimental epilepsy during pregnancy. Methods: Eighteen Swiss Albino rats were randomly divided into three groups (n=6): experimental group, saline-injected sham surgery group, and intact control group. In the experimental group of rats, an acute grand mal epileptic seizure was induced by 400 IU penicillin-G administration into their intrahippocampal CA3 region with a stereotaxic device during the 13th day of their pregnancy. On the first neonatal day, pups were perfused with intracardiac fixative solution under anesthesia, and newborn hippocampi were dissected surgically for light and electron microscopic examinations. In an immunohistochemical study using Rat-401 monoclonal antibody and peroxidase, nestin expression was analyzed in the developing hippocampal tissue. Results: Histologically, normal migration and hippocampal maturation were determined in the newborn rat hippocampus in the control and the sham-operated groups. It was observed that the morphological structure of hippocampus in the experimental group corresponded to the early embryonal period. Most importantly, it was found that nestin (+) cell density was increased in the experimental epilepsy group in contrast to the control and sham groups. Conclusion: It has been concluded that epileptic seizures during embryonic life may cause impaired hippocampal neurogenesis and maturation, explaining the potentially harmful effects of epileptic seizures on the embryo at the early stage of neuronal differentiation. This is the first report regarding the alterations in nestin expression in newborn rat hippocampus. In the light of such findings, it will also be necessary to evaluate the functional consequences of a variety of epileptic seizures on learning and memory in neonates. © Springer-Verlag 2004