Appearance and differentiation of NADPH-d-positive neurons in rat prefrontal cortex following exposure to retinoic acid.

Retinoic acid (RA) is a biologically active form of vitamin A. Teratogenicity has been observed in pregnant mammals exposed to high doses of vitamin A. We investigated the distribution of nitrergic neurons in rat prefrontal cortex (PFC) at developmental stages 7 days to young adulthood under physiological conditions and after prenatal application of all trans-RA. The neurons were studied histochemically using NADPH-diaphorase, which stains neurons dark blue. We found that nitrergic neurons differentiate rapidly and reach structural maturity by the end of the second week of postnatal development. We found that the processes of the neurons of nitrergic neurons of 14-day-old rats in the RA group were shorter than those of the control group. Our findings suggest that excess RA during the prenatal period may influence the development and morphology of NADPH-diaphorase positive neurons, probably by RA-specific receptors in the PFC of 14-day-old rats. RA receptors may be the main effector molecules responsible for the changes of dendrite length induced by all-trans RA. During later development, changes are not observed, probably due to maturation of the nervous system.

Response of distant regions affected by diaschisis commissuralis in one of the most common models of transient focal ischemia in rats.

Stroke induces widespread changes in the brain. In this paper, we monitored some markers of early (2 h) and delayed events (1, 3 and 7 days of reperfusion) initiated by middle cerebral artery occlusion in core/penumbra counterparts of the non-ischemic hemisphere (i.e. contra-core and contra-penumbra). Our results showed that a profound transient drop (2 h and 3 days) of protein synthesis was measured in the contra-core, while the contra-penumbra exhibited translation over-activity at the same time. Glutamate release was detected only in the contra-core, with a peak on the first day. Degenerating neurons became visible in the striatum (day 1), followed by cortex (day 3), earlier in contra-penumbra and later in contra-core. Moreover, the loss of NADPH diaphorase-positive neurons in the non-ischemic hemisphere was detected, with the greatest drop at the first day. Total microglia also started to fall, the earliest in the contra-penumbra region of the striatum (day 1), followed by the contra-core of the striatum and both cortex regions at the seventh day. In conclusion, transient focal ischemia affects remote regions of the brain and initiates processes involved in neuronal degeneration in an order which corresponds to the tissue sensitivity to ischemia, namely earlier in the contra-penumbra, and afterwards in the contra-core. The mechanism of secondary damage would influence the progressive neuronal loss of more distant brain regions.

Three-dimensional CAD/CAM imaging of the maxillary sinus in ageing process.

OBJECTIVES: During the physiological ageing process atrophy of the alveolar bone appears in vertical direction. This bone resorption causes pushing the limits of the maxillary sinus at the expense of a degraded bone. The sinus volume increases due to the facial development in children and adolescents or during the ageing process due to the loss of teeth and bone mass. The main aim of this study is to determine the sinus shape and sinus floor morphology related to age. MATERIALS AND METHODS: Human adult male and female cadaveric heads (aged 37 to 83 years) with different dental status were used. The three-dimensional CAD/CAM software was used to scan the solid impressions of the maxillary sinus to visualize the real sinus shape and sinus floor. Subsequently, other findings are shown in tables and evaluated graphically. RESULTS: The maxillary sinus morphology, its relationship to the nasal cavity, the sub sinus alveolar bone height, displacement of the lowest and highest points of sinus, and the sinus relationship to the roots of the upper teeth were studied and evaluated. Some septa, crests, and the prominent infraorbital canal were also found in the area of the sinus floor. CONCLUSIONS: This paper provides a unique view on the maxillary sinus and its changes during the ageing process with preserved topographical relations in a representative sample of the Slovak population. The visualization of the maxillary sinus anatomy is necessary in the diagnosis and treatment plans for dental implants and during current surgical procedures.

Unilateral occurrence of five different thyroid arteries-a need of terminological systematization: a case report.

This article highlights an unusual and unilateral variation in the blood supply to the inferior portion of the thyroid gland observed on the right lobe during anatomy dissection course. The rare variation of the occurrence of two anomalous arteries: the middle thyroid artery and the aberrant accessory inferior thyroid artery, and one uncommon variant, the thyroid ima artery, was detected in an adult female cadaver. The two generally constant arteries, the superior thyroid artery and the inferior thyroid artery, have been found in their usual anatomical location. Both the middle thyroid artery and aberrant accessory inferior thyroid artery arose from the right common carotid artery. The middle thyroid artery coursed as a very short branch ventromedially to enter the inferior lateral portion of the right lobe of the thyroid gland. It was at the same level, in which the inferior thyroid artery reached the lateral border of the thyroid gland. The aberrant accessory inferior thyroid artery originated similarly, from the ventromedial surface of the right common carotid artery and passed to supply the inferior pole of the right lobe. The thyroid ima artery was found to arise from the brachiocephalic trunk, entering the isthmus of the thyroid gland. Information about the embryological background might be helpful to clarify why such a type of variation occurs. It is necessary to understand the possible existence of this anomaly, to carry out successful radical neck dissection and to minimize the risk of postoperative complications in patients.

Vitamin A and amygdala: functional and morphological consequences.

Intake of vitamin A is essential for correct embryonic development of the central nervous system (CNS). Its increased intake during gravidity can cause various malformations and dysfunctions of the CNS. In our work, we intended to investigate the effect of vitamin A on emotional behavior and morphology of nitrergic neurons in basolateral nucleus of the rat amygdala. For this purpose, we have administered retinoic acid (RA), a metabolite of vitamin A, to females on 14-16 days of pregnancy at a dose 1 mg RA/kg body weight. Adult progeny of these mothers were tested in elevated plus maze test, the most widely used test for measuring anxiety-like behavior. After the test, brains of the rats were processed for reduced nicotinamide adenine dinucleotide phosphate diaphorase histochemistry, which is commonly used to mark cells containing nitric oxide synthase. Our results have shown that RA applied during the sensitive phase of intrauterine development influences emotional behavior of adult rats. Animals exposed to RA had increased levels of fear and anxiety, which has been manifested by reducing the time spent in the open arms of plus maze test. Interestingly, detected behavioral changes do not correlate with the result of our morphological study. The number and morphology of nitrergic neurons in amygdala were very similar in experimental and control rats. Our results demonstrate that prenatal exposure to RA has no effect on morphological structure of amygdala, but influences its function.

Prenatal effects of retinoic acid on lumbar spinal cord development and liver antioxidants in rats.

During embryonic and early postnatal development, retinoic acid (RA) regulates genes that control neuronal differentiation and neurite outgrowth from the neural tube. The effects of high levels of RA on the CNS can be detected via nitric oxide (NO), which plays a crucial role in neural transmission. The aim of the study was to investigate the prenatal influence of high levels of RA on postnatal development of nitrergic structures in lumbar spinal cord and antioxidant status. RA was administered orally at a dose of 10mg/kg body weight to pregnant female Wistar rats during days 8-10 of gestation. Neuronal nitric oxide synthase (nNOS) of lumbar spinal cord sections was processed for visualization via nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry on postnatal day one, day twenty-one and in adults. The results suggest that prenatal administration of high levels of RA is not associated with postnatal morphological changes in nNOS-positive neurons in the rat lumbar spinal cord. An estimation of the activity of enzymes related to the storage of retinoid in the liver showed possible side effects. Suppression and deepening of superoxide dismutase activity persisted into adulthood, and a concurrent downregulation of glutathione reductase was noted. A decrease in reduced glutathione persisted until adulthood when other compensatory mechanisms were probably active to maintain an appropriate level.

Nitrergic neurons during early postnatal development of the prefrontal cortex in the rat: histochemical study.

The presence of nitrergic cells in the prefrontal cortex has been confirmed, however little is known about the postnatal development of these cells. Nitrergic neurons were studied histochemically by using NADPH-diaphorase staining in the prefrontal cortex of male Wistar rats from postnatal day 7-21 (P7-21). Neuronal NADPH-diaphorase is a nitric oxide synthase that provides a specific histochemical marker for neurons producing nitric oxide (NO). NO acts as a neurotransmitter and intracellular signaling molecule in the nervous system. We observed in 7 day old rats NADPH-d containing neurons that were intensely stained. These neurons were bipolar with a short dendrite with average length of 23 µm. During the second postnatal week, the neurons were mainly bipolar and were rarely multipolar. By P14 the cells were located primarily in cortical layers III-VI. Nitrergic neurons of the 21 day old rats were histochemically identified as multipolar cells with long radial extending dendrites. Dendrites of neurons in 14 and 21 day old rats were a similar length with an average of 57 µm. These results suggest that nitrergic neurons differentiate during a relatively short period of time and reach their structural maturity by the end of the second week of postnatal development.

Postnatal development of spinal cord and liver antioxidant status in the young of retinol-overdosed female rats.

The metabolic form of vitamin A, retinol, has a pivotal role in the nervous system development and neuronal differentiation, both during embryogenesis through maternal-fetal support and in the early postnatal life. Retinoic acid was administered orally at a dose of 10 mg/kg body weight to pregnant female rats through days 8-10 of gestation. Spinal cord sections were processed for histochemical visualization one day after birth and on day 21, when weaning is expected. NADPH-diaphorase (NADPH-d)-positive neurons were found in the dorsal horn, around the central canal, and at the intermediolateral cell column on postnatal days 1 and 21 in both control and experimental groups. There were no NADPHd-positive structures in the ventral horn. The results suggest that prenatal administration of high doses of retinoic acid is not associated with postnatal morphological changes in NADPH-d-positive neurons in the rat spinal cord. Levels of antioxidants and related enzymes in retinoid storage organs were measured to estimate possible side effects. The activities of enzymes detoxifying superoxide radicals and peroxides were supressed after birth. A decrease in the level of reduced glutathione was observed on postnatal day 21, indicating an unbalanced redox environment.

Anatomical study of the roots of cranial parasympathetic ganglia: a contribution to medical education.

A major key to increasing the safety of cranial surgery is a thorough understanding of anatomy. The anatomy of the head is of fundamental interest to dental and medical students early in their studies. Clinically, it is mostly relevant to surgeons who are performing interventions and reconstruction in the maxillofacial region, skull base, and the orbit. However, the level of appropriate anatomical knowledge necessary for general and special medical and surgical practice is still under discussion. This study maps the significant areas and structures of the head that are not normally accessible during dissection courses because of time and difficulties involved in the preparation. The detailed photodocumentation enriched by diagrams provides a view of structures until now only partially documented. Three parasympathetic ganglia are located in hardly accessible areas of the head - inside the orbit, infratemporal fossa, and in the pterygopalatine fossa. No detailed photographs have been found in current anatomical textbooks and atlases in relation to the morphology of fibers (roots) connected to the ciliary, otic, and pterygopalatine ganglia. Therefore, this study focused on the detailed display of sensory, sympathetic, and parasympathetic roots of ganglia to provide relevant photodocumentation and an improvement in human anatomy teaching. This study also confirms that cadaver dissection provides an excellent opportunity for the integration of anatomy and clinical medicine into the early clinical training of undergraduate dental and medical students. We believe this article, because of the details mentioned above, will be beneficial not only for the future anatomical undergraduate but also for postgraduate education.

Postnatal development of nitrergic and cholinergic structures in rat spinal cord.

Nitric oxide (NO) is known to be a freely diffusible gaseous neurotransmitter that is not requiring synaptic connection to exert its effects. Nitric oxide synthase (NOS), the enzyme responsible for NO synthesis can be visualised by nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry. Other neurotransmitter is a classical neurotransmitter acetylcholine (ACh), regulated by enzyme acetylcholinesterase (AChE) that hydrolyses the acetylcholine after its releasing. This work is presenting results of histochemical study of the NADPH-d and AChE expression (nitrergic and cholinergic neurons) in the spinal cord (SC) during various periods in its development. Specimens from Wistar rat pups in the age ranging from 1st to 21st postnatal days (P1-P21) have been compared with those of adult rats (P90). Transverse sections of the SC were evaluated by light microscope. In adults, the NADPH-d positivity was detectable in the neurons of superficial and deep layers of the dorsal horn, pericentral area and in the area of preganglionic autonomic nuclei. AChE positive structures were seen in the same locations as previous ones with the exception of two locations: in superficial layers of the dorsal horn AChE staining was absent, while in the ventral horn the groups of AChE positive motoneurons were found. At the perinatal period both NADPH-d and AChE positive neurons were stained from slight to moderate intensity only. During later developmental periods the staining gradually increased and achieved adult level of intensity on the day P21. Our results confirmed the presence of nitrergic and cholinergic neurons in investigated areas of the SC and indicated their fully functioning of NADPH-d and AChE positive structures in SC from the third postnatal week.

Chemokines as possible targets in modulation of the secondary damage after acute spinal cord injury: a review.

In spite of many promising experimental studies, an effective treatment dramatically eliminating the secondary damage after spinal cord injury (SCI) is still missing. Since clinical data on the therapeutical effect after methylprednisolone treatment are not conclusive, new therapeutical modalities targeting specific components of secondary spinal cord damage needs to be developed. It is known that immune cells are recruited to injury sites by chemokines, which are small, structurally similar proteins released locally at the site of inflammation. Hence, this review was aimed to summarize possible roles of chemokines in the inflammation following SCI as well as to identify possible new therapeutical targets which can potentially be effective in ameliorating individual components of this inflammatory response. Data concerning inflammation reduction together with techniques improving axonal growth, cell replacement and remyelinization, may be crucial to move a small step forward in an attempt to make paraplegic and quadriplegic patients to walk.

Morphologic and volumetric studies of the meibomian glands in elderly human eyelids.

PURPOSE: To study the microscopic structure of postmortem human Meibomian glands (MGs) in the elderly. METHODS: Human MG samples from left lower eyelids were obtained at autopsy from 5 men and 4 women with a mean age of 63.1 +/- 7.67 years. The tissues were fixed and embedded in paraffin. Serial transverse sections 5 mum thick were stained with hematoxylin and eosin (H&E), van Gieson, and Masson blue stains. Computer-assisted 3-dimensional reconstructions of MGs were performed, and morphologic and volumetric data were analyzed. RESULTS: The average length of human MGs in the nasal, central, and temporal areas was 1.551 +/- 0.43, 1.654 +/- 0.47, and 1.594 +/- 0.57 mm, respectively. The average surface area of the glands in the nasal, central, and temporal areas was 0.029 +/- 0.03, 0.033 +/- 0.01, and 0.056 +/- 0.03 mm, respectively. The average volume of glands in the nasal, central, and temporal areas was 0.054 +/- 00.4, 0.056 +/- 0.03, and 0.053 +/- 0.03 mm, respectively. A circular, floral arrangement of acini, surrounding the terminal duct just deep to the skin, is probably responsible for the circular arrangement seen clinically around each healthy orifice. We confirmed that most glands are embedded within a cylindrical, connective tissue matrix. CONCLUSIONS: We report the dimensions of normal Meibomian acini in an older population. Some structural features observed may explain normal physiologic landmarks or contribute to glandular pathophysiology.

The effect of long-term reduction of aortic blood flow on spinal cord gray matter in the rabbit. Histochemical study of NADPH-diaphorase.

1. The aim of this work was to study the influence of reduced aortic blood flow on NADPH-diaphorase (NADPH-d) staining in the gray matter of L4-S3 spinal cord segments. 2. Surgery was performed on the abdominal aorta of the rabbit. Spinal cord ischemia was introduced by infrarenal aortic constriction to 30% from the normal blood flow. Animals were allowed to survive 1 week, 1 month and 3 months after surgery. Neurological outcome was studied in relation to the duration of aortic occlusion. The NADPH-d histochemistry was used for the visualisation of spinal cord sections. 3. The most affected area of the spinal cord was pericentral region, and slight changes were seen in the NADPH-d activities of both dorsal and ventral horns. One week after surgery, NADPH-d positive pericentral neurons were almost unchanged in their shape and intensity of staining, the only difference was seen in slightly increased staining of the background around the central canal. One month following surgery neurons exhibited shrinkage or were swollen, NADPH-d staining was less intensive in the pericentral zone and positively stained vessels were present. 4. Three months of ischemia influenced the NADPH-d activity: (a) In the pericentral region were seen intensively NADPH-d stained neurons almost normal in shape of their bodies but with shortened processes or without them; (b) NADPH-d staining of neuropil was greatly enhanced mostly around the central canal and in the dorsal commissure; (c) Numerous vessels were present in the pericentral zone and in the location of the ventral horn. 5. It can be concluded that the reduction of blood flow in the abdominal aorta makes most changes in the pericentral region of the rabbit spinal cord. Increased NADPH-d staining of neuropil and the presence of positively stained vessels reflect increased NADPH-d/NOS production in the spinal cord gray matter after long-term incomplete aortic occlusion.