Remote psychophysical testing of smell in patients with persistent olfactory dysfunction after COVID-19.

Olfactory dysfunction associated with coronavirus 2 (SARS-CoV-2) infection is in most cases transient, recovering spontaneously within a few days. However, in some patients it persists for a long time, affects their everyday life and endangers their health. Hence, we focused on patients with persistent loss of smell. The aim of this study was to evaluate olfactory dysfunction using a standardized test. Due to the pandemic, olfactory testing was performed online. Smell tests (Odorized Markers Test, OMT) were sent home to the patients. Together with the smell self-testing, participants reported and assessed several parameters (age, sex, subjective assessment of smell and taste, nasal patency, etc.) in an online questionnaire. Based on the questionnaire outcomes, the results were sent to the patients along with a list of participating otolaryngologists who provided them with professional care. From March to June 2021, 1025 patients requested smell testing, of these, 824 met the inclusion criteria of this study. The duration of the olfactory dysfunction at the time of testing ranged from 1 month to 1 year. Using the OMT, impaired smell ability-anosmia or hyposmia-was confirmed in 82.6% of participants. A total of 17.4% of participants were determined to be normosmic however, more than 50% of them complained of parosmia and/or phantosmia. Our study demonstrates the relevance of psychophysical smell testing and its suitability for remote use during the pandemic. This study also revealed several correlations between prolonged olfactory dysfunction and the monitored parameters.

Maternal High-Energy Diet during Pregnancy and Lactation Impairs Neurogenesis and Alters the Behavior of Adult Offspring in a Phenotype-Dependent Manner.

Obesity is one of the biggest and most costly health challenges the modern world encounters. Substantial evidence suggests that the risk of metabolic syndrome or obesity formation may be affected at a very early stage of development, in particular through fetal and/or neonatal overfeeding. Outcomes from epidemiological studies indicate that maternal nutrition during pregnancy and lactation has a profound impact on adult neurogenesis in the offspring. In the present study, an intergenerational dietary model employing overfeeding of experimental mice during prenatal and early postnatal development was applied to acquire mice with various body conditions. We investigated the impact of the maternal high-energy diet during pregnancy and lactation on adult neurogenesis in the olfactory neurogenic region involving the subventricular zone (SVZ) and the rostral migratory stream (RMS) and some behavioral tasks including memory, anxiety and nociception. Our findings show that a maternal high-energy diet administered during pregnancy and lactation modifies proliferation and differentiation, and induced degeneration of cells in the SVZ/RMS of offspring, but only in mice where extreme phenotype, such as significant overweight/adiposity or obesity is manifested. Thereafter, a maternal high-energy diet enhances anxiety-related behavior in offspring regardless of its body condition and impairs learning and memory in offspring with an extreme phenotype.

The potential adverse effect of 2.45 GHz microwave radiation on the testes of prenatally exposed peripubertal male rats.

In utero development of organs is easily influenced by many environmental factors. The aim of this study was to elucidate the effect of microwave radiation (MR) at a frequency of 2.45 GHz and a specific absorption rate of 1.73 W/kg on intrauterine development of testis. Pregnant albino rats were exposed to whole-body MR for 2 hours per day throughout the pregnancy. Male offspring (n=12, age 35 days) were not exposed to MR after birth. The study revealed that MR applied in utero induced apparent structural changes in the testes, such as irregular shape of seminiferous tubules, significant decrease in the diameter of seminiferous tubules (p<0.05) and in the height of the germinal epithelium (p<0.01), disorganisation of germ cells, desquamations of immature germ cells, formation of giant multinucleated cells, and significant (p<0.01) expansion of the interstitium. At the level of transmission electron microscopy, there were observed basement membrane irregularities in seminiferous tubules, vacuolation of the cytoplasm and adversely affected organelles in Sertoli cells, germ cells, Leydig cells, peritubular and endothelial cells. The tight junctions between adjacent Sertoli cells were often incomplete, and necrotizing germ cells were more numerous in experimental animals compared to controls. Enhanced necrotizations of germ cells proved by a Fluoro Jade C method, and declined germ cells proliferation confirmed by proliferating cell nuclear antigen analysis, were detected in MR exposed animals. Our results revealed that the prenatal exposure to MR had an adverse effect on the postnatal testicular development in rats.

Relationship between Blood Vessels and Migration of Neuroblasts in the Olfactory Neurogenic Region of the Rodent Brain.

Neural precursors originating in the subventricular zone (SVZ), the largest neurogenic region of the adult brain, migrate several millimeters along a restricted migratory pathway, the rostral migratory stream (RMS), toward the olfactory bulb (OB), where they differentiate into interneurons and integrate into the local neuronal circuits. Migration of SVZ-derived neuroblasts in the adult brain differs in many aspects from that in the embryonic period. Unlike in that period, postnatally-generated neuroblasts in the SVZ are able to divide during migration along the RMS, as well as they migrate independently of radial glia. The homophilic mode of migration, i.e., using each other to move, is typical for neuroblast movement in the RMS. In addition, it has recently been demonstrated that specifically-arranged blood vessels navigate SVZ-derived neuroblasts to the OB and provide signals which promote migration. Here we review the development of vasculature in the presumptive neurogenic region of the rodent brain during the embryonic period as well as the development of the vascular scaffold guiding neuroblast migration in the postnatal period, and the significance of blood vessel reorganization during the early postnatal period for proper migration of RMS neuroblasts in adulthood.

Low Fos expression in newly generated neurons of the main and accessory olfactory bulb following single maternal separation.

The main and accessory olfactory bulbs (MOB and AOB) are unique in that they produce new neurons throughout adulthood. Despite the recent knowledge about the involvement of postnatally generated cells in several aspects of olfaction, the functional role of these neurons is still not sufficiently understood. The function of newly generated olfactory bulb neurons is primarily investigated in relation to activities related to smell. Stress-induced activation of new olfactory neurons has not yet been studied. Thus, our work was aimed to investigate whether a stressful event, such as maternal separation (MS) can induce Fos expression in postnatally-born neurons in the MOB and AOB. Rat pups were exposed to single maternal separation (SMS) for 2 h at the postnatal days: P7, P14, and P21. Quantification of immunohistochemically labeled Fos + cells revealed that exposure to SMS in different age stages during the first postnatal month stimulates activity in cells of individual MOB/AOB layers in an age-dependent manner. In order to find out whether newly generated cells in the MOB/AOB could express Fos protein as a response to SMS, newborn rats were administrated with the marker of proliferation, bromodeoxyuridine (BrdU) at P0, and three weeks later (at P21) colocalization of Fos and BrdU in the neurons of the MOB and AOB was assessed. Quantitative analysis of BrdU/Fos double-labeled cells showed that Fos is expressed only in a small number of postnatally generated cells within the MOB/AOB. Our results indicate that postnatally generated MOB/AOB neurons are less sensitive to stress caused by MS than preexisting ones. LAY SUMMARY Our results showed that single maternal separation (SMS) is a stressful event that in age-dependent manner stimulates cellular activity in the main and accessory olfactory bulb (AOB) - the structures dedicated to odor information processing. The low level of Fos expression in newborn neurons of the main and accessory bulb indicates that postnatally generated cells are less sensitive to neonatal stress than preexisting neurons.

Hypothermic treatment after computer-controlled compression in minipig: A preliminary report on the effect of epidural vs. direct spinal cord cooling.

The aim of the present study was to investigate the therapeutic efficacy of local hypothermia (beginning 30 min post-injury persisting for 5 h) on tissue preservation along the rostro-caudal axis of the spinal cord (3 cm cranially and caudally from the lesion site), and the prevention of injury-induced functional loss in a newly developed computer-controlled compression model in minipig (force of impact 18N at L3 level), which mimics severe spinal cord injury (SCI). Minipigs underwent SCI with two post-injury modifications (durotomy vs. intact dura mater) followed by hypothermia through a perfusion chamber with cold (epidural t≈15°C) saline, DMEM/F12 or enriched DMEM/F12 (SCI/durotomy group) and with room temperature (t≈24°C) saline (SCI-only group). Minipigs treated with post-SCI durotomy demonstrated slower development of spontaneous neurological improvement at the early postinjury time points, although the outcome at 9 weeks of survival did not differ significantly between the two SCI groups. Hypothermia with saline (t≈15°C) applied after SCI-durotomy improved white matter integrity in the dorsal and lateral columns in almost all rostro-caudal segments, whereas treatment with medium/enriched medium affected white matter integrity only in the rostral segments. Furthermore, regeneration of neurofilaments in the spinal cord after SCI-durotomy and hypothermic treatments indicated an important role of local saline hypothermia in the functional outcome. Although saline hypothermia (24°C) in the SCI-only group exhibited a profound histological outcome (regarding the gray and white matter integrity and the number of motoneurons) and neurofilament protection in general, none of the tested treatments resulted in significant improvement of neurological status. The findings suggest that clinically-proven medical treatments for SCI combined with early 5 h-long saline hypothermia treatment without opening the dural sac could be more beneficial for tissue preservation and neurological outcome compared with hypothermia applied after durotomy.

Disrupted migration and proliferation of neuroblasts after postnatal administration of angiogenesis inhibitor.

In adult rodents, neuroblasts originating from the subventricular zone migrate tangentially through the rostral migratory stream (RMS) toward the olfactory bulb where they differentiate into interneurons. Neuroblasts in the RMS migrate in chains for a long distance along specifically arranged blood vessels which promote their migration. Although blood vessels in the neurogenic region of the forebrain are present early in development, their rearrangement into this specific pattern takes place during the first postnatal weeks. Here we examined the relevance of this rearrangement to the migration-guiding "scaffold" for the neurogenic processes in the RMS such as cell migration and proliferation. To disturb the reorganization of blood vessels, endostatin - an inhibitor of angiogenesis, was administered systemically to rat pups during the first postnatal week. Ten days or three months later, the arrangement of blood vessels, migration and proliferation of cells in the RMS were assessed. As we expected, the inhibition of angiogenesis disrupted rearrangement of blood vessels in the RMS. The rearrangement's failure resulted in a strong disruption of the mode and direction of neuroblast migration. Chain migration failed and neuroblasts migrated out of the RMS. The inhibition caused a slight increase in the number of proliferating cells in the RMS. The consequences were more obvious ten days after the inhibition of angiogenesis, although they persisted partly into adulthood. Altogether, here we show that the process of rearrangement of blood vessels in the RMS during the early postal period is crucial to ensure the regular course of postnatal neurogenesis.

Analysis of Fos expression in the rat olfactory neurogenic region following single exposure to maternal separation during different neonatal stages.

Accumulating evidence confirms that the exposure of neonatal rats to maternal separation can significantly alter individual processes of postnatal neurogenesis in the olfactory neurogenic region - the subventricular zone (SVZ) and the rostral migratory stream (RMS). To establish the stressful influence of MS on postnatal neurogenesis we have investigated whether altered olfactory environment caused by short-term MS induces expression of Fos protein in the SVZ/RMS and in the olfactory cortical area - anterior olfactory nucleus (AON) of neonatal rats. Pups were separated from mothers for 2 hours at the postnatal days 7, 14 and 21. Immunohistochemically labeled Fos protein was assessed. Our results revealed that single exposure to MS is a stressful event that selectively and in age-dependent manner stimulates cellular activity in the SVZ and AON. A few Fos+ cells were found in the SVZ of P21 control animals and MS significantly increased their number. This suggests that some SVZ cells are included in the circuitry, which is activated by MS and that these cells have complete equipment for the Fos signal transduction. MS significantly increased the number of Fos+ cells in the AON in all age stages examined suggesting that its effect is mediated by olfaction.

Astrocytic and vascular scaffolding for neuroblast migration in the rostral migratory stream.

New neurons are continuously being added to the olfactory bulb (OB) of adult rodents that are generated in the subventricular zone (SVZ), distant by a few millimeters. Neuronal precursors have to overcome this long distance without the radial-glial migratory scaffold, in contrast to migration mode during embryonic development. The previous model explains migration of precursors from the SVZ through the rostral migratory stream (RMS) to the OB as a movement of neuroblasts along each other, ensheathed by astroglial tubes. Recent results indicate that blood vessels are suitable candidates for neuronal migration guidance in the RMS. These novel findings have changed the former concept accounting for neuronal precursor migration. The aim of our study was to map a pattern of vascularization in the RMS of adult rats and to investigate mutual relations among blood vessels, neuroblasts and astrocytes in this area. Detailed morphological analysis revealed that blood vessels in the RMS are organized in a specific manner. In most of the RMS extent, blood vessels run parallel to the outline of the migratory pathway. Interestingly, the caudal part of the RMS has a unique vasculature organization in which blood vessels create a spiral-like configuration. Chains of neuroblasts enveloped by astrocytes largely align along blood vessels. The exception is the caudal part of the RMS where neuroblasts do not follow non - parallel blood vessels. Our morphological findings suggest that blood vessels and astrocytes may cooperatively form physical substrate - scaffold for the neuroblasts migration in the RMS of adult rats.

Structural and ultrastructural study of rat testes influenced by electromagnetic radiation.

This study was conducted to investigate the influence of whole-body electromagnetic radiation (EMR) on testicular parenchyma of Wistar rats. Sexually mature rats were subjected to pulsed electromagnetic field at frequency of 2.45 GHz and mean power density 2.8 mW/cm(2) by 3-h daily applications for 3 wk. Tissue samples were obtained 3 h after the last irradiation and processed by histological techniques for light and transmission electron microscopy. Testes showed apparent degenerative changes of seminiferous epithelium. The seminiferous tubules were mostly irregular in shape, and seminiferous epithelium contained a number of empty spaces of different size. Subsequently, groups of sloughed epithelial cells were often found inside the lumina of tubules. Except for relatively unchanged Sertoli cells, some locations of basal compartment of seminiferous epithelium contained shriveled Sertoli cells with dark cytoplasm. These areas showed degenerative features including necrotizing and shriveled spermatogonia surrounded by empty irregular spaces, and undulating basement membrane. The intertubular spaces were enlarged but interstitial Leydig cells did not show any marked morphological changes. Evidence demonstrates the adverse effects of EMR on testicular parenchyma in rats.

Diverse effect of different odor stimuli on behavior and Fos protein production in the olfactory system neurogenic region of adult rats.

Previously it has been demonstrated that processes of postnatal neurogenesis in the olfactory system neurogenic region-the subventricular zone (SVZ), rostral migratory stream (RMS), and olfactory bulb (OB) can be significantly altered by different factors of an environment. However, the mechanisms involved in regulation of neurogenesis by exogenous factors in the olfactory system remain unclear. The purpose of the present study was to contribute to the understanding of these mechanisms by immunohistochemical assessment of Fos protein induction in areas of adult neurogenesis. To evaluate the coordinate activation of Fos production in neurons of the olfactory system neurogenic region, a brief exposure to artificial odor (eau de Cologne) or naturalistic odor (cat odor) has been used in alert rats. Our results revealed that the effects of these odors are easily distinguishable at both the behavioral and the morphological level. Cat odor induced greater changes in anxiety level, and produced typical pattern of Fos activation in the accessory olfactory bulb (AOB), a brain region associated with defensive behavior. An important finding is, that next to distinct Fos expression in the OB and the AOB, Fos positive cells have been found also within the SVZ/RMS of the odor stimulated rats. Interestingly, Fos expression in the RMS was detected only after exposure to artificial odor stimulus. These results provide new evidence that some SVZ/RMS cells have complete prerequisites necessary for the Fos signal transduction cascade.

Effects of short-duration electromagnetic radiation on early postnatal neurogenesis in rats: Fos and NADPH-d histochemical studies.

The immediate effects of whole body electromagnetic radiation (EMR) were used to study postnatal neurogenesis in the subventricular zone (SVZ) and rostral migratory stream (RMS) of Wistar rats of both sexes. Newborn postnatal day 7 (P7) and young adult rats (P28) were exposed to pulsed electromagnetic fields (EMF) at a frequency of 2.45 GHz and mean power density of 2.8 mW/cm(2) for 2 h. Post-irradiation changes were studied using immunohistochemical localization of Fos and NADPH-d. We found that short-duration exposure induces increased Fos immunoreactivity selectively in cells of the SVZ of P7 and P28 rats. There were no Fos positive cells visible within the RMS of irradiated rats. These findings indicate that some differences exist in prerequisites of proliferating cells between the SVZ and RMS regardless of the age of the rats. Short-duration exposure also caused praecox maturation of NADPH-d positive cells within the RMS of P7 rats. The NADPH-d positive cells appeared several days earlier than in age-matched controls, and their number and morphology showed characteristics of adult rats. On the other hand, in the young adult P28 rats, EMR induced morphological signs typical of early postnatal age. These findings indicate that EMR causes age-related changes in the production of nitric oxide (NO), which may lead to different courses of the proliferation cascade in newborn and young adult neurogenesis.

Odor enrichment influences neurogenesis in the rostral migratory stream of young rats.

The olfactory bulb is one of a few brain structures characterized by high plasticity due to the fact that new neurons are continually integrated into the olfactory bulb circuit throughout life. The new cells originate from the subventricular zone of the forebrain and migrate through the rostral migratory stream (RMS) to the olfactory bulb that also represents the first synaptic relay of the olfactory system. Data accumulating in recent years have confirmed that sensory inputs can influence the level of postnatal neurogenesis in the olfactory bulb. In this study, we studied neurogenesis in the rostral migratory stream of Wistar albino rat pups after exposure to an odor-enriched environment. The rats were olfactory stimulated twice daily with different odorants from the day of their birth up to 1, 2 or 3 weeks, respectively. Using bromodeoxyuridine, a marker of cell proliferation, we found an increased number of proliferating cells in the rostral migratory stream of rat pups submitted to olfactory stimulation. Conversely, the number of dying cells, labeled with the fluorescent dye Fluoro Jade-C, was down-regulated in groups of rats exposed to an odor-enriched environment.

Maternal separation induced alterations of neurogenesis in the rat rostral migratory stream.

1. The aim of our study was to investigate the possibility that maternal separation, an experimental model for studies of early environmental influences, has an effect on postnatal neurogenesis in neurogenic pathway--the rostral migratory stream (RMS). 2. Rat pups were subjected to maternal separation daily for 3 h, starting from the first postnatal day (P1) till P14 or P21. In the first two groups, brains were analyzed at the age of P14 and P21, respectively. In the third group, after 3 weeks of maternal separation, 1 week of normal rearing was allowed, and the brains were analyzed at P28. The controls matched the age of maternally separated animals. Dividing cells were labeled by bromodeoxyuridine; dying cells were visualized by Fluoro-Jade C and nitric oxide (NO) producing cells by NADPH-diaphorase histochemistry. 3. Quantitative analysis of proliferating cells in the RMS showed that maternal separation decreased the number of dividing cells in all experimental groups. This decrease was most prominent in the caudal part of the RMS. The amount of dying cells was increased at the end of 3 weeks of maternal separation as well as 1 week later. The number of differentiated nitrergic cells in the RMS was increased at the end of 2 or 3 weeks of maternal separation, respectively. Besides quantitative changes, maternally separated animals showed an accelerated maturation of nitrergic cells. 4. Our results indicate that an exposure of rats to adverse environmental factors in early postnatal periods may induce acute site-specific changes in the RMS neurogenesis.

Immunohistochemical study of postnatal neurogenesis after whole-body exposure to electromagnetic fields: evaluation of age- and dose-related changes in rats.

It is well established that strong electromagnetic fields (EMFs) can give rise to acute health effects, such as burns, which can be effectively prevented by respecting exposure guidelines and regulations. Current concerns are instead directed toward the possibility that long-term exposure to weak EMF might have detrimental health effects due to some biological mechanism, to date unknown. (1) The possible risk due to pulsed EMF at frequency 2.45 GHz and mean power density 2.8 mW/cm(2) on rat postnatal neurogenesis was studied in relation to the animal's age, duration of the exposure dose, and post-irradiation survival. (2) Proliferating cells marker, BrdU, was used to map age- and dose-related immunohistochemical changes within the rostral migratory stream (RMS) after whole-body exposure of newborn (P7) and senescent (24 months) rats. (3) Two dose-related exposure patterns were performed to clarify the cumulative effect of EMF: short-term exposure dose, 2 days irradiation (4 h/day), versus long-term exposure dose, 3 days irradiation (8 h/day), both followed by acute (24 h) and chronic (1-4 weeks) post-irradiation survival. (4) We found that the EMF induces significant age- and dose-dependent changes in proliferating cell numbers within the RMS. Our results indicate that the concerns about the possible risk of EMF generated in connection with production, transmission, distribution, and the use of electrical equipment and communication sets are justified at least with regard to early postnatal neurogenesis.

Cell proliferation in the adult rat rostral migratory stream following exposure to gamma irradiation.

One of the few areas of the adult CNS, that are known to be competent for neuronal proliferation, is the subventricular zone (SVZ) lining the brain lateral ventricles. Cells proliferating in the SVZ migrate along a defined pathway, the rostral migratory stream (RMS), where their proliferation continues until reaching the olfactory bulb. 1. In relation to the fact that brain is, in general, regarded as a radioresistant organ composed from non dividing cells, the aim of the present study was to investigate effect of ionizing radiation on proliferating cell numbers in the RMS of adult rats. 2. Male Wistar rats were investigated 25 and 80 days after whole body gamma irradiation with the dose of 3 Gy. Dividing cells were labeled by bromodeoxyuridine (BrdU). BrdU-positive cells were counted by Disector program. The mean number of BrdU(+) cells in the whole RMS and in its individual parts (vertical arm, elbow, and horizontal arm) was evaluated. 3. Temporary increase in proliferating cell number (by 30%) was seen in the whole RMS at the 25th day after irradiation. 4. The most expressive increase occurred in the vertical arm (by 60%) and elbow (about 37%). The values reduced till the 80th day after exposure. Our results show that ionizing irradiation significantly influences the extent of cell proliferation and migration in the adult rat RMS.

The number of proliferating cells in the rostral migratory stream of rat during the first postnatal month.

The objective of this study was to analyze neurogenesis in the rat rostral migratory stream (RMS) during the first postnatal month.1. During the early postnatal development some morphological changes, concerning the RMS thickness, shape, and the olfactory ventricle persistence at P0 were observed. 2. Bromodeoxyuridine (BrdU) immunohistochemistry and subsequent quantification of proliferating cells showed significant age-dependent changes. The highest number of proliferating cells was found at P3 and significant decrease of BrdU-positive cells at P7 rats. At P28, the number of proliferating cells reached the level of P0 rats.

Age-related changes of NADPH-diaphorase positivity in the rat rostral migratory stream.

Accumulating evidence confirms that nitric oxide (NO), a versatile diffusible signaling molecule, contributes to controling of adult neurogenesis. We have previously shown the timing of NADPH-diaphorase (NADPH-d) positivity within the rat rostral migratory stream (RMS) during the first postnatal month. The present study was designed to describe further age-related changes of NO presence in this neurogenic region. The presence of NO synthesizing cells in the RMS was shown by NADPH-d histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry. The phenotypic identity of nitrergic cells was examined by double labeling with GFAP and NeuN. Systematic qualitative and quantitative analysis of NADPH-d-positive cells was performed in the neonatal (P14), adult(5 months) and aging (20 months) rat RMS. 1. Nitrergic cells with different distribution pattern and morphological characteristics were present in the RMS at all ages examined. In neonatal animals, small, moderately stained NADPH-d-positive cells were identified in the RMS vertical arm and in the RMS elbow. In adult and aging rats a few labeled cells could be also detected in the RMS horizontal arm. NADPH-d-positive cells in adult and aging rats were characterized by long varicose processes and displayed dark labeling in comparison to the neonatal group. 2. Double immunolabeling has revealed that nNOS-immunoreactivity co-localized with that of NeuN. This indicates that nitrergic cells within the RMS are neurons. 3. Quantitative analysis showed that the number of NADPH-d-positive cells increases with advancing age. The presence of NO producing cells in the RMS of neonatal adult and aging rats indicates, that this proliferating and migratory area is under the influence of NO throughout the entire life of the animals.

Ependyma as a possible morphological basis of ischemic preconditioning tolerance in rat spinal cord ischemia model: nestin and Fluoro-Jade B observations.

1. To test our hypothesis that a transient nonlethal ischemic insult benefits the lumbosacral spinal cord ischemic injury, nestin, the marker of proliferating cells, and Fluoro-Jade B, the marker of degenerating cells, were used in rats. Morphological outcome was evaluated after 12-min ischemia versus 12-min ischemia preconditioned by 3-min ischemic period and 30-min recirculation (IPC), in each group followed by 2, 3, and 4 days of posttreatment survival. 2. Twelve-minute ischemia, inducing nestin-positivity in ependyma and reactive astrocytes at the L(1-3) spinal cord segments, shows this region as the viable region of spinal cord in all postischemic survival periods. On the other hand, abundance of Fluoro-Jade B-positive cells, distributed throughout the dorsal horn and intermediate zone of L4-S2 segments, points out the most injured spinal cord region by ischemia. 3. After the same ischemic insult in IPC rats only a few nestin-positive ependymal cell and reactive astrocytes appeared beside the nestin-positive vessels in the lower lumbar and sacral spinal cord segments of all survival periods. The appearance of nestin-positive cells in the spinal cord segments, which "should have been affected" by ischemia indicates protection of this region by the IPC treatment. 4. The number and density evaluation of Fluoro-Jade B fluorescent cells of L4-S2 segments after ischemia and IPC confirmed that degenerating cells were significantly reduced in the IPC rats in all survival periods. 5. Our results showing the immunohistochemical response of epemdyma, committed to the presence of viable tissue, indicate that the ependymal cells may contribute to the ischemic resistance in the IPC rats.

NADPH-diaphorase positivity in the rostral migratory stream of the developing rat.

The NADPH-diaphorase (NADPH-d) histochemical technique is commonly used to localize the nitric oxide (NO)-producing enzyme NO synthase (NOS) in neural tissues. In this study, we have used NADPH-d histochemistry to examine the spatio-temporal appearance of nitrergic cells in the rat rostral migratory stream (RMS) during postnatal development. The presence of NADPH-d-positive cells was evident from postnatal day 10.