How to write an umbrella review? A step-by-step tutorial with tips and tricks

The number of meta-analyses (MA) and systematic reviews (SR) on various medical issues has increased during the last two decades. The MA and SR results may differ from one another due to a number of factors such as inaccurate or diverse searches through the databases, discrepancies in the extraction process or in statistical analysis, among others. Some results may even contradict one another, resulting in confusion among readers. Umbrella reviews (UR) have allowed the collection of all available data on a medical issue into one concise study, making it the source of evidence-based medical knowledge to the highest degree. Furthermore, UR can resolve those problems by collecting all data and taking into account both MA and SR, making it the superior tool for physicians. Although the pros of UR are clear and the overall popularity of these types of study has increased tremendously, there is no available step-by-step guide on how to conduct one. Therefore, the objective of the present study was to provide researchers with a detailed tutorial on how to conduct an UR. UR represent the next major step in the advancement of evidence-based medicine, with great practical potential for physicians looking for the most up-to-date data on their topic of interest. We hope that our step-by-step guide may be a useful tool for researchers conducting UR in the future.

Role of brain-derived neurotrophic factor in shaping the behavioural response to environmental stressors

Brain-derived neurotrophic factor (BDNF) is an important neurotrophin involved in an integration of the brain activity in physiological and pathological conditions, with formation of a short- and long-term functional and structural neuroplasticity. This process proceeds, with a changeable dynamics, in the subsequent stages of ontogenesis. In addition to many other functions in the central nervous system, BDNF is also involved in shaping a response to stress stimuli in the form of precisely adjusted behavioural reactions involving the limbic system, and the endocrine system with stimulation of the hypothalamic-pituitary-adrenal axis (HPA). Although almost every stressor increases the activity of the HPA, the neuronal response to it can vary substantially. This may be due to involvement of different neurotransmitter pathways, neuromodulators and neurohormones, as well as changes in gene expression. It is widely accepted that BDNF synthesis and secretion are modulated by stress. Furthermore, age is an important factor influencing the BDNF expression in response to different stressors. In this work, we focused on the analysis of the role of mild stressful stimuli, which commonly occur in the natural environment, on changes in BDNF expression at various stages of ontogenetic development. Although, the presented data comes from animal studies, probably similar mechanisms of stress regulation are also present in humans. This comprehensive review shows that the influence of stressors on the BDNF expression depends on many factors, including a type and duration of a stressor, time of neurotrophin detection, animal's resistance to stress, brain area, and genotypic characteristics of an individual. A more detailed understanding of the mechanisms shaping stress reactions, including the role of BDNF, may be of both theoretical and practical importance, allowing designing more effective strategies for preventing and treating stress itself and the stress-related disorders.

Pyruvate dehydrogenase deficiency: morphological and metabolic effects, creation of animal model to search for curative treatment

The main source of energy for brain and other organs is glucose. To obtain energy for all tissue, glucose has to come through glycolysis; then as pyruvate it is converted to acetyl-CoA by pyruvate dehydrogenase complex (PDC) and finally enters citric acid cycle. What happens when one of these stages become disturb? Mutation in genes encoding subunits of PDC leads to pyruvate dehydrogenase deficiency. Abnormalities in PDC activity result in severe metabolic and brain malformations. For better understanding the development and mechanism of pyruvate dehydrogenase deficiency the murine model of this disease has been created. Studies on a murine model showed similar malformation in brain structures as in the patients suffered from pyruvate dehydrogenase deficiency such as reduced neuronal density, heterotopias of grey matter, reduced size of corpus callosum and pyramids. There is still no effective cure for PDC-deficiency. Promising therapy seemed to be ketogenic diet, which substitutes glucose to ketone bodies as a source of energy. Studies have shown that ketogenic diet decreases lactic acidosis and inhibits brain malformations, but not the mortality in early childhood. The newest reports say that phenylbutyrate increases the level of PDC in the brain, because it reduces the level of inactive form of PDH. Experiments on human fibroblast and zebra fish PDC-deficiency model showed that phenylbutyrate is promising cure to PDC-deficiency. This review summarizes the most important findings on the metabolic and morphological effects of PDC-deficiency and research for treatment therapy.

The influence of early postnatal chronic mild stress stimulation on the activation of amygdala in adult rat

Amygdala is a limbic structure involved in the stress response. The immunohistochemical and morphometric methods were used to examine whether the chronic mild psychological stress during the early postnatal period would change activation of amygdaloid nuclei in response to the same stressor in adult. In the study we focused on the role of neurons containing calbindin (CB), calretinin (CR), parvalbumin (PV) and nitric oxide synthase (NOS). The rats were divided into three groups: control non-stressed animals and two experimental: EI consisted of animals that were exposed to acute stress in the high-light, open-field test (HL-OF) at P90 (P - postnatal day) and EII consisted of rats that were exposed to chronic stress in HL-OF, daily during the first 21 postnatal days and then once at P90. The scheme of activation of amygdaloid nuclei under stress in EI and EII group was similar. The highest density of c-Fos-ir cells (c-Fos - a marker of neuronal activation) was demonstrated by the medial nucleus (Me) and bed nucleus of the accessory olfactory tract (BAOT). The amygdaloid nuclei diversity after HL-OF was determined by the high activation of the NOS-ir cells in the Me and NOS- and CR-ir cells in the BAOT. These are probably projection neurons involved in modulation of defensive, reproductive and autonomic behavior in stress response and creation/storage of aversive memory. However, in comparison with EI group, significant decrease in density of c-Fos-ir cells, in almost all amygdaloid nuclei of EII group was revealed. Particularly in BAOT and Me the strong decrease of activity of NOS- and CR-ir neurons was observed. It probably results in attenuation of stress responses what, depending on the circumstances, can be adaptive or maladaptive.

Organisation of the dopamine neuronal subsets within midbrain of the feathertail glider (Acrobates pygmaeus, Acrobatidae, Marsupialia)

The Marsupial feathertail glider has a unique set of morphological, anatomical and behavioural features that make it a promising model for study of primate evolution. Among them it has many locomotor adaptations to arboreal life, such as diagonal gait of movements, gliding, fast climbing and running along branches. These ecological and behavioural specialisations could result in differences in anatomy of the brain systems involved in their integration. It is well acknowledged that dopaminergic neurons are involved in motor control, motivation and cognition. Due to the fact that there are no data on morphological organisation of dopaminergic system in the midbrain of this species, we decided to investigate it using immunohistochemical and quantitative methods. Our study showed that the general distribution and characteristics of the dopaminergic cells within midbrain nuclei of the pygmy acrobat is similar to that in other species, but it lack the substantia nigra compact part - ventral tier and "tail" of the substantia nigra subnuclei. This study provides the first description of the dopaminergic cells and nuclei in the midbrain of the feathertail glider and we hope it will start interest in the neurobiology of this species.

Age-Related (Aged vs. Adult) Comparison of the Effect of Two Mild Stressors on the Nerve Growth Factor (NGF) in the Rat Hypothalamic Supraoptic Nucleus (SON) - Immunohistochemical Study

The ontogenetic period of life and stress can have different effects on the nerve growth factor (NGF) in the hypothalamus. The aim of our study was to investigate the influence of two mild stressors, acute and chronic exposure to forced swim (FS) or high-light open field (HL-OF), on neurons containing NGF. Immunofluorescence staining was used to reveal the density of NGF-immunoreactive (ir) cells in the hypothalamic supraoptic nucleus (SON) in adult (postnatal day 90; P90) and aged (P720) rats. The P90 and P720 rats that were subjected to acute and chronic FS showed no differences in the density of NGF-ir neurons in the SON compared with nonstressed rats. However, a significant increase in NGF-ir cells was noted after acute but not after chronic HL-OF only in P90 rats. What is more, there were no age-related (P90 vs. P720) changes in the density of NGF-ir neurons in non-stressed and FS- or HL-OF-stressed rats. Our results indicate that acute HL-OF was the only factor inducing changes in the density of NGF-ir neurons in the SON of adult rats. This could be related to the neuroprotective role of NGF-ir cells in response to acute HL-OF. The absence of age-dependent changes in the density of NGF-ir neurons may indicate that the ageing processes in SON do not generate changes in the NGF immunoreactivity of its neurons.

Reduced level of synapsin I protein in the rat striatum after intraventricular administration of proteasome inhibitors: preliminary studies

BACKGROUND

We have recently described changes present in nigrostriatal terminals after intraperitoneal administration of MG-132 and changes that occur in the walls of the rat lateral ventricle after intraventricular administration of MG-132, lactacystin and epoxomicin - different classes of proteasome inhibitors. Substances that inhibit ubiquitin-proteasome system (UPS) activity, are intensively studied due to their potential role as novel therapeutic strategies in the treatment of cancer and ischaemia-reperfusion injury in the brain. The aim of this study is to determine the influence of intraventricular administration of MG-132, lactacystin and epoxomicin on the level in the rat striatum synapsin I - one of the most prominent neuron-specific phosphoproteins in the brain.

MATERIALS AND METHODS AND RESULTS

Two weeks after administration of studied proteasome inhibitors, substantial reduction (up to 80%) of synapsin I was ob-served in the rat striatum. Because neurons, and especially dopaminergic ones, are sensitive to the depletion of proteasome function, we assume that observed synapsin I decrease may reflect changes in population of striatal neurons and/or nigrostriatal terminals.

CONCLUSIONS

Understanding of cellular mechanisms standing behind our findings needs further studies, and could provide valuable contribution to the discussion on the mechanisms linking UPS inhibition and survival of neurons.

Nerve growth factor (NGF) immunoreactive neurons in the juvenile rat hippocampus: response to acute and long-term high-light open-field (HL-OF) or forced swim (FS) stress stimulation

This study aimed at examining and comparing the influence of two different stress stimuli on the density (number of cells/mm²) of nerve growth factor (NGF) containing neurons in the hippocampal CA1 and CA3 pyramidal cell layers and the dentate gyrus (DG) granule cell layer in juvenile rats (P28; P-postnatal day). The high-light open-field (HL-OF) test and forced swim (FS) test were employed to investigate the effects of a single, 15-min acute exposure and repeated (15 min daily for 21 days) long-term exposure to stress. In order to detect NGF-ir neurons, immunohistochemical (-ir) techniques were used. In comparison with nonstressed animals, acute and long-term HL-OF or FS stimulation resulted in a marked increase (P<0.001) in the density of NGF-ir containing cells in all the hippocampal structures. The frequency of stress application (acute vs. long-term), however, did not have a substantial impact on the studied parameter, with the exception of the CA3 sector, where a decreased density (P<0.001) of NGF-ir neurons was observed after long-term exposure to FS. It may be concluded that a rise in the density of NGF-ir neurons in the juvenile rat hippocampus after exposure to HL-OF or FS stressors could have affected the activity of the hypothalamic-pituitary-adrenocortical (HPA) stress axis. Prolonged HL-OF or FS stress was probably aggravating enough not to trigger the habituation process. The type of stressor applied (HL-OF vs. FS) was not essentially a factor determining the density of NGF-ir cells in the hippocampus.

Stress-induced changes of interleukin-1beta within the limbic system in the rat

The aim of this study was to investigate the influence of two periods of life, namely P28 and P360, on the changes in interleukin-1beta (IL-1beta) immunoreactivity (-ir) in the hippocampus (CA1, CA3, DG) and amygdala (central-CeA, medial-MeA) caused by acute and repeated open field (OF), or by forced swim (FS) exposition. Rats were divided into groups: non-stressed, exposed to acute (one-time for 15 min) and chronic stressors (21 days for 15 min daily). We found IL-1beta-ir in the control group to be higher in P360 than in P28. In P28, under OF and FS exposure, IL-1beta-ir in the CeA remained unaltered but increased in the MeA and in the hippocampus after acute and chronic stress. In P360 no changes were observed in the IL-1beta-ir level after acute and chronic stimulation. These data demonstrate that only the levels of IL-1beta-ir in juvenile rat brains are affected by FS and OF. Additionally, there was no significant difference between FS and OF stimulation in IL-1beta-ir.

Changes in NGF/c-Fos colocalization in specific limbic structures of juvenile and aged rats after open field stimulation

Changes in NGF release during stressful events have been associated with the activation of neurons expressing NGF receptors. This study examined the influence of acute stress-induced stimulation on NGF/c-Fos colocalization in the following limbic regions: the paraventricular (PV) nucleus of the hypothalamus, medial (MeA) nucleus of the amygdala, and CA3 hippocampus. Juvenile (P21) and aged rats (P360) were exposed to a 15-minute acute open field (OF) test. Double immunofluorescence staining, used to detect NGF-ir and c-Fos-ir cells, revealed a higher percentage of NGF/c-Fos-ir neurons in the P21 control group than in the P360 control group. Under OF acute stimulation, a statistically significant (p < 0.05) increase of NGF/c-Fos level in CA3 of juvenile animals and in PV and CA3 of the aged rats was observed. These observations indicate that the investigated structures in both age groups show a different response to acute OF stimulation. Acute OF affects the levels of NGF/c-Fos more significantly in aged rats.

Endopiriform nucleus connectivities: the implications for epileptogenesis and epilepsy

Several anterograde and retrograde tracing studies have provided detailed information on the afferent and efferent projections as well as the intrinsic connectivities of the endopiriform nucleus (EN). Here, we summarise EN connectional data and the principles of their organisation and discuss the role they may play in the development and spread of epileptic seizures.

Distribution of neuronal nitric oxide synthase (nNOS)-immunoreactive elements in the rabbit piriform cortex

The piriform cortex (PC), the primary olfactory cortex, is involved in the processes of learning and stress response and possibly plays an important role in epileptogenic activity. The results of several recent studies suggest that those PC neurons that contain neuronal nitric oxide synthase (nNOS) may play a key role during spatial learning and in the modulation of initiation, propagation and generalisation of seizures in various experimental models and may influence neuronal vulnerability after epileptic insults. The aim of this study was to characterise the pattern of distribution and morphology of nNOS-immunoreactive elements in PC of the adult rabbit. The co-localisation of nNOS and calretinin (CR) was also studied. The pattern of nNOS-ir within the rabbit PC is similar to that described previously in other mammals. The morphology of nNOS-ir elements, namely varicose fibres and Cajal-Retzius cells, suggest that NO has an important influence on PC function. Surprisingly, in the rabbit PC nNOS-ir elements show a very low level of co-localisation with CR-ir.

The influence of acute and chronic open-field exposure on the hippocampal formation: an immunohistochemical study

The hippocampus plays a role in new learning, memory and emotion and is a component of the neuroanatomical stress circuit. The structure is involved in terminating hypothalamic-pituitary-adrenocortical (HPA) axis responses to stress and attenuates stress responses by shutting off this axis. The immunoreactivity (-ir) of c-Fos, NGF and its receptor TrkA following acute and chronic open-field stress were studied in CA1-CA3 and the DG of the hippocampus. The material consisted of 21 male adult rats divided into three groups: nonstressed (control) animals and rats exposed to acute (15 min once) and chronic (15 min daily for 21 days) aversive stimulation (open-field exposure). The brains were stained with use of immunohistochemical methods for c-Fos, NGF or TrkA. In the animals exposed to acute open-field stress the number of c-Fos-, TrkA and NGF-ir cells was higher in all the structures studied than in the control animals. However they were differentiated only in c-Fos immunoreactivity. In the rats exposed to chronic open-field stress the number of c-Fos-ir cells in the structures of the hippocampal formation studied was smaller than in rats exposed to acute stress and was comparable to that in the control group. No differences were observed between the groups exposed to acute and chronic stress in the number of TrkA-ir cells in the structures under investigation. The number of NGF-ir neurons in CA1 and CA2 was lower after exposure to chronic than after exposure to acute stress but was still higher than that in the control group. Our findings indicate that neurons of CA1-CA3 and the DG are engaged in the stress response after acute as well as chronic open-field exposure. This is probably related to the important role of the hippocampus in processing new spatial information as well as in the habituation processes, although these appear to have different mechanisms.

The pathophysiology of intracerebral haemorrhage

Spontaneous intracerebral haemorrhage carries a high mortality rate and treatment of the disease raises more questions then answers. Mass effect, ischaemia and toxicity of blood components are responsible for brain tissue damage. Initially occurring disturbances of cerebral blood flow have a temporary character and do not play a key role in the pathology of intracerebral haematoma. Oedema formatting in the 24-48 hours after intracerebral bleeding is the result of multidirectional processes. The pathological mechanism that underlines it is the function of activation of systemic complement and cascade of coagulation. In the light of these findings, further clinical and experimental investigations should be focused on these factors.

The technique of inhalation anaethesia in experimental investigation in the rat

The rat is the most frequently used animal in scientific inquiry conducted for the purpose of advancing basic knowledge that may lead to an improvement in the results of treatment. Understanding of the pharmacological properties of inhalation anaesthetics, in combination with monitoring of their concentration in the inspired and end-tidal gas, together provide safe and precise control of the depth of the anaesthesia. However, accurate application of the inhalation method of anaesthesia requires special equipment for the delivery and effective scavenging of inhalation anaesthetics.

Quantitative analysis of influence of sevoflurane on the reactivity of microglial cells in the course of the experimental model of intracerebral haemorrhage

BACKGROUND

Microglial cells play an important role in the pathophysiology of intracerebral haemorrhage. We have examined the possible influence of sevoflurane on the reactivity of microglial cells during intracranial haemorrhage.

METHODS

Forty adult male rats were divided into two groups. All animals were anaesthetized with fentanyl, dehydrobenzperidol and midazolam. In the experimental group animals additionally received sevoflurane 2.2 vol% end-tidal concentration. Intracranial haemorrhage was produced through infusion of blood into the striatum. The microglial cell population (numerical density of immunoreactive cells and their distribution) was assessed on days 1, 3, 7, 14 and 21 after producing a haematoma using antibodies OX42 and OX6.

RESULTS

In the control group significant differences in the density of OX42-ir cells between 3rd and 7th (81.86 vs. 129.99) (95% CI: -77.99 to -18.25, P = 0.0035) and between 14th and 21st (105.36 vs. 63.81) (95% CI: 13.21 to 69.89, P = 0.006) survival days were observed. However, significant increase of percentage of amoeboid OX42-ir cells between 3rd and 7th (0.98 vs. 48.71) (95% CI: -52.17 to -43.30, P = 0.0001) and between 7th and 14th (48.71 vs. 58.47) (95% CI: -13.96 to -5.55, P = 0.0002) and then their decrease - between 14th and 21st (58.47 vs. 31.74) (95% CI: 22.52 to 30.93, P = 0.0001) days of observation were noted. In the sevoflurane groups OX42-ir cells were not found. On the 3rd day the density of OX6-ir cells in the sevoflurane group was significantly lower than that in the control group (12.39 vs. 34.57) (95% CI: -49.78 to -2.96, P = 0.02). The percentage of an amoeboid form of OX6-ir cells was significantly lower in the sevoflurane group than that in the control group (27.31 vs. 82.03) (95% CI: -72.52 to -36.92, P = 0.0001) (58.76 vs. 82.37) (95% CI: -38.81 to -8.41, P = 0.003) (42.87 vs. 81.55) (95% CI: -53.23 to -24.10, P = 0.0001) respectively for 3rd, 7th and 14th days of survival.

CONCLUSION

Administration of sevoflurane during anaesthesia in animals with intracerebral haemorrhage evoked a decrease of activation of the microglial cells.

The immunoreactivity of c-Fos, NGF and its receptor TrkA after open-field exposure in the central and medial nuclei of the rat amygdala

The amygdala is a critical component of the neuroanatomical stress circuit. It plays a role in the generation of responses to emotional stimuli. The central (CeA) and medial (MeA) amygdaloid nuclei are implicated in activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. The immunoreactivity (-ir) of c-Fos, NGF and its receptor, TrkA, following acute and chronic open-field stress were studied in the CeA and MeA nuclei of the amygdala. The material consisted of 21 male adult rats divided into three groups: non-stressed (control) animals, rats exposed to acute (once only lasting 15 min) and chronic (15 min daily over 21 days) aversive stimulation (open-field exposure). The brains were stained with the use of immunohistochemical methods for c-Fos, NGF or TrkA. In the control rats c-Fos-, TrkA- and NGF-ir cells were observed in the nuclei studied, but the quantity varied, being moderate or high (immunoreactive to TrkA and NGF) or low (immunoreactive to c-Fos). In the animals exposed to acute open-field stress the number of c-Fos-ir, NGF-ir and TrkA-ir cells in the nuclei under examination was differentiated but higher than that in the control animals. In the animals exposed to chronic open-field stress the number of c-Fos-ir cells in the nuclei studied was similar and was smaller than those in animals exposed to acute stress. The number of TrkA-ir neurons was also lower in comparison to that in animals exposed to acute stress. However, no significant differences in the number of NGF-ir cells were observed between the groups exposed to acute and chronic stress. Diverse expression of c-Fos protein following both acute and chronic stress stimulation may prove the functional heterogeneity of the amygdaloid nuclei investigated. The decrease observed in both c-Fos- and TrkA-ir in MeA (only TrkA in CeA) of animals exposed to chronic stress may indicate the phenomenon of habituation.

Influence of the "open field" exposure on calbindin D28K, calretinin, and parvalbumin containing cells in the rat midbrain - developmental study

The aim of our study was to analyze the influence of the open field (OF) exposure on: 1. Distribution of c-Fos positive nuclei in: ventral tegmental area, substantia nigra, periaqueductal gray. 2. Appearance of calbindin-D28k, calretinin and parvalbumin in midbrain neurons that are engaged in the stress response. 3. Changes of c-Fos and calcium-binding proteins expression during maturation. The material consisted of Wistar rats of age between 0 and 90 days. The OF exposure was applied throughout 10 min and 90 min before the death of the animals. The brain sections were double stained using the antibodies against c-Fos, CB, CR or PV. Our results showed that in all studied nuclei age-related increase of c-Fos expression (without changing of its distribution properties) was found. PV didn't show any co-localization with c-Fos in neurons of studied regions at any ages, however some PV-immunoreactive (PV-ir) basket-like structures around c-Fos-immunoreactive (c-Fos-ir) neurons were observed. In the youngest group of rats c-Fos-ir cells and cells immunoreactive for CB and CR constituted separate neuronal populations. During maturation increases in the level of their co-localization with c-Fos was observed. We may conclude that in adult rat midbrain structures CB-immunoreactive (CB-ir) and CR-immunoreactive (CR-ir) cells (probably projection neurons) are mainly activated in the stress response following OF exposure. In the contrary PV-ir cells has only an indirect (modulatory) influence upon the c-Fos-ir cells.

Immunoreactivity of c-Fos, NGF and its receptor TrkA in the periventricular zone of the rat hypothalamus after open field exposure

The immunoreactivity (ir) for c-Fos, NGF and TrkA, following an acute and chronic open field stress, were studied in the periventricular zone of rat hypothalamus. Adult rats were divided into three groups: control, exposed to acute (single exposure--15 minutes) and chronic (multiple exposures--15 minutes daily for 21 days) open field stress. In the control rats neurons immunoreactive to c-Fos, TrkA and NGF were found. The number of TrkA- and NGF-ir cells was high, whereas this of c-Fos-ir ones was low. In animals exposed to acute open field stress the number of c-Fos-ir cells in the examined nuclei varied, however it was much higher than that in the control animals. The number of TrkA-ir neurons in all the studied nuclei was also higher than that in the control animals, but the increase of the number of NGF-ir neurons was not observed in supraoptic nucleus. In the animals exposed to chronic open field stress the number of c-Fos-ir cells was increased in comparison to that in the control rats. After chronic stress exposure the number of TrkA-ir neurons in supraoptic nucleus remained high in comparison to that in animals exposed to acute stress, whereas it was decreased in other studied nuclei. No significant differences in the number of NGF-ir cells were observed between the groups exposed to the acute and chronic stress. Observed decrease of c-Fos- and TrkA-ir in the studied nuclei in the animals suffering from chronic stress in comparison with the acute one may indicate the occurrence of habituation phenomenon. This phenomenon does not concern NGF-ir.

Apoptosis in the course of experimetal intracerebral haemorrhage in the rat

Intracerebral haematoma was produced in 25 adult rats by infusion of 100 microl of autologous blood into the striatum. The animals' brains were removed at 1, 3, 7, 14 and 21 days after production of the haematoma. The TUNEL method was used to detect DNA fragmentation and TUNEL-positive cells were qualified. TUNEL-positive cells were already found on the first day of observation and were present for three weeks after haematoma production. These results provide evidence that programmed cell death is associated with intracerebral haemorrhage.

The influence of sevoflurane on the reactivity of astrocytes in the course of the experimental intracerebral haemorrhage in rat

40 adult Wistar rats were divided into two groups depending on the applied anaesthesia. In both groups animals were generally anaesthetized with fentanyl, dehydrobenzperidol administered intraperitoneally and midazolam given intramuscularly. In the second group (SEVO) animals received sevoflurane of 2.2 vol% end-tidal concentration. Intracerebral haematoma was produced through infusion of 100 microl of autologous blood into the striatum. Each group was divided into five subgroups depending on the length of survival period: 1, 3, 7, 14, 21 days. The astrocytic population was studied by means of anti-GFAP staining. Stereological analysis was applied to estimate the numerical density of immunoreactive cells and the distribution of their types. On 7th day of observation the density of GFAP-immunoreactive astrocytes in SEVO was lower (p<0,05) than that in the control group. In the control group, the increase (p<0.05) of per cent of activated astrocytes between the 1st and 3rd survival day was noted, which remained at this level till the end of observation. In SEVO group, the increase (p<0.05) of per cent of activated astrocytes between the 3rd and 7th day and the decrease (p<0.05) between the 14th and 21st survival day were observed. During days of observation the per cent of activated astrocytes was lower (p<0.05) in the SEVO group than that in the control group. Administration of sevoflurane during anaesthesia to animals with intracerebral haemorrhage has evoked not only the delay of the activation of astrocytes but also decrease in its level.

Open field stress and neurons containing calcium-binding proteins in the piriform cortex of the rat

In the present study we wanted to check whether the expression of the c-Fos protein (the marker of cellular activity) appears in cells containing calcium-binding proteins (CaBPs) in animals exposed to the open field test. Eight adult Wistar rats were examined. In the first step the open field test was applied throughout 10 minutes. After perfusional fixation brains were frozen and cut on the cryostat in the coronal plane and stained with the standard immunohistochemical method. Sections were double stained for c-Fos and CaBPs: parvalbumin (PV), calbindin (CB), calretinin (CR). c-Fos positive cells were localized predominantly in layers II and III of the piriform cortex (PC). The double labeling study showed that neurons containing CaBPs are rarely c-Fos-immunoreactive. Often PV-positive and CB-positive fibers surround c-Fos-positive neurons in layers II and III in a form of a basket. It seems that cells containing CaBPs are not directly involved in the response to aversive stimuli but cells containing those calcium-binding proteins might influence directly c-Fos positive neurons of PC.

Postnatal development of the basolateral complex of rabbit amygdala: a stereological and histochemical study

The aim of the study was to estimate developmental changes in the rabbit basolateral complex (BLC) by stereological and histochemical methods. Material consisted of 45 brains of New Zealand rabbits (aged from 2 to 180 days, P2 to P180) of both sexes, divided into nine groups. The following parameters were estimated: volume of the cerebral hemisphere; volume of the whole BLC and of particular BLC nuclei; neuronal density and total number of neurons in these nuclei. Developmental changes in acetylcholinesterase (AChE) activity in the BLC were also examined. The volume of the cerebral hemisphere increased until P30, whereas volumes of nuclei increased for longer--until P90. The density of neurons in all nuclei studied reached the level characteristic for an adult animal at about P30. The total number of neurons in the dorsolateral division of the lateral nucleus (Ldl) stabilized the earliest--between P30 and P60, whereas in the ventromedial division of the lateral nucleus (Lvm), basomedial (BM) and basolateral (BL) nuclei the number stabilized later--between P60 and P90. AChE activity appears minimal in the BLC on P2, reaches a maximum on P30 and then decreases to the level characteristic of an adult animal on P60. AChE activity was greater in BL than in other nuclei in all age groups. Reaching adult AChE activity 1 month earlier than the total number of neurons in the BLC may indicate a role of the cholinergic system in BLC maturation.

The relationships between neurons containing dopamine and nitric oxide synthase in the ventral tegmental area

Ventral tegmental area (VTA) is a heterogeneous group of dopaminergic cells which contains interfascicular (IF), parabrachial (PBP) and rostral linear (RLi) nuclei. Neurons of this area are involved in the regulation of motor and motivational aspects of behavior and reveal high neuronal plasticity. Among many various neurotransmitters and neuromodulators, nitric oxide (NO) is localized in this region. In the present study, we investigated morphology and distribution of nitric oxide synthase (NOS)-positive neurons in VTA and their colocalization with dopaminergic neurons. The study was performed on six adult Wistar rats. After perfusional fixation, the brains were cut, immunostained for tyrosine hydroxylase (TH) and NOS and studied by confocal laser microscopy. In each of the three studied nuclei of VTA we investigated three different neuronal populations. Numerous TH-immunoreactive (TH-ir) and NOS-immunoreactive (NOS-ir) neurons are present in the studied region. Among them, a considerable number showed coexistence of both neurotransmitters. The populations of TH-ir and NOS-ir neurons interact with each other as manifested by the presence of NOS-ir endings on TH-ir neurons and vice versa. Taking the above into account, it may be suspected that NO is involved in the modulation of dopaminergic transmission.

Relation between the age of specimen and the shrinkage of brain frozen sections

The aim of the study was to assess the effect of age of the animal upon the real thickness of the frozen sections. The study was performed on 19 rabbit brains. The thickness of the frozen sections regardless of their staining is age-dependent. The relation is proportional during the period from 7 to 180 postnatal day and characterizes both immunohistochemical as well as cresyl violet-stained sections; moreover, changes of the section thickness proceed parallelly. It is suggested that especially for some stereological parameters all required procedures should be standardized to achieve comparable and unbiasedly interpretable results.

The influence of storage time upon the real thickness of the histological brain sections

The aim of the study was to assess the effect of storage time on the actual thickness of the histological sections. The study was performed on 5 brains of adult Wistar rats. The most rapid changes occur at the beginning of the storage process, after about one month the dynamics of changes decreases, but still the thickness of the sections diminishes. It is suggested that quantitative analyses should be performed in similar period of time and the critical care should be taken not only of the chemicals and procedures used, but also of the control of environmental factors.

The developmental pattern of c-fos expression in the rat thalamus following open-field stress stimulation

The thalamic nuclei with their defined set of input-output connections are the primary channel for information flow to the cerebral cortex. Several data suggest that neurons of that area are involved in the response to various aversive stimulations. However the pattern of activation seems to depend on the stress model as well as the stage of maturation. In the present study we would like to check which nuclei of the thalamus show expression of c-fos in the response to the "open field test", and how this response pattern changes during the maturation process. 30 rats of age ranged from P0 to P120 (P-postnatal day) were studied. The experimental group was exposed to the "open field test" for 10 minutes. After perfusion and fixation, brains were cut and stained for c-fos with immunohistochemical method. Our results showed that during development the pattern of c-fos activity in the thalamic nuclei after stress stimulation undergoes significant changes. Distinct c-fos expression was observed in the paraventricular nucleus, intergeniculate leaflet and ventral lateral geniculate nucleus. These findings suggest that these nuclei may play a direct role in the stress reaction involved in the response to the "open field test".

General anaesthesia in rats undergoing experiments on the central nervous system

The rat is one of the species most commonly used in laboratory practice. Numerous publications concerning various aspects of morphology and physiology are based on the results obtained in this species. It make these results comparable and under some precautions enables to transpose into the relationships observed in humans. Each experimental project must obtain the permission of the Local Ethical Committee, as well as comply with the regulations of the European Communities Council, outlined in the "European Convention for the protection of vertebrate animals used for experimental and other scientific purposes". Adequate pre-operative care can eliminate or reduce the incidence of many complications, which may occur during anaesthesia. General anaesthesia in experimental practice can be achieved using a variety of drugs and ways of administration, among others inhalational or intravenous. The side effects of anaesthetic agents can be reduced in this way. Knowledge of the effect of anaesthetics on the cerebral circulation, metabolism and intracranial pressure in both normal and pathological conditions is crucial for neurobiological purposes. Many anaesthetic agents depress respiration, which can result in hypoxia, hypercapnia and acidosis. To maintain blood carbon dioxide and oxygen concentration in the physiological range, it is necessary to apply tracheal intubation and artificial ventilation. However, even when using sophisticated equipment, the role of basic clinical observation, such as the colour of the blood shed in the operation field, breathing depth and frequency, cannot be overestimated. The importance of monitoring mean arterial blood pressure and intracranial pressure in experiments on the central nervous system is fundamental. Special attention should be paid to controlling the temperature and monitoring the fluid balance. Appropriate postoperative care can have a decisive influence on the final results of the research.

The amygdaloid complex of the rabbit--morphological and histochemical study

The aim of the present paper is to describe the morphology and topography of the nuclei of the amygdaloid complex in the rabbit. In the current study we also investigated the intensity of the enzymatic reaction for acetylcholinesterase (AChE) in the amygdaloid complex and the morphology of its neurones. Material consisted of 5 brains of adult New Zealand rabbit, stained either with cresyl violet or for AChE activity. Although, as in other mammals, the rabbit amygdala consists of two main nuclear groups (corticomedial and basolateral), it reveals a peculiar morphology pattern, forming a transition structure between those observed in the cat and rat. Especially characteristic is the arrangement of the basolateral complex. Within that the ventromedial division of the lateral nucleus seems to be the largest, while its dorsolateral division--the smallest. The arrangement of the corticomedial complex in the rabbit is similar to both the cat and rat. In the rabbit the highest acetylcholinesterase activity is found in the basolateral nucleus and the nucleus of the lateral olfactory tract. The lowest AChE staining is observed in the cortical and medial nuclei, amygdalohippocampal and anterior amygdaloid areas and intercalated masses.

Differentiation in the immunocytochemical features of intrinsic and cortically projecting neurons in the rat claustrum -- combined immunocytochemical and axonal transport study

Retrograde axonal transport method of the fluorescent tracer FluoroGold (FG) was combined with immunocytochemistry to investigate the occurrence of nitric oxide synthase (NOS), somatostatin (SOM), neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP) in both intrinsic and cortically projecting neurons of the rat claustrum. Only NOS was detected in both the scattered projecting neurons and internal neurons of the claustrum. Approximately 20% of NOS-immunoreactive neurons in the claustrum were also retrogradely labeled with FG after tracer injections into the frontal cortex. The other substances were exclusively confined to the population of interneurons, which mainly displayed an oval, round or fusiform shape and a medium size. Apart from the neuronal somata, the proximal parts of the dendritic arborization were clearly visible. The immunoreactive neurons were randomly distributed in the claustrum and their neuronal size and shape did not differ in the various parts of the studied structure. Co-localization of NOS and SOM or NOS and NPY was reported. In conclusion, SOM, VIP and NPY do not appear to play a significant role in the claustro-cortical projection but are most probably involved in modulation and information transfer in the claustrum. The appearance of NOS in both cortically projecting and intrinsic neurons of the claustrum may be indicative of a fundamentally different role in the functioning of the claustro-cortical loop.

Effect of sevoflurane on intracranial pressure and cardiovascular function in rabbits with experimental intracerebral haematoma

BACKGROUND

Sevoflurane is one of the newest volatile anaesthetic agents. The effect of sevoflurane on ICP in conditions of intracranial pathology is essential from the clinical point of view but still not sufficiently clear. The aim of the study was to examine the effects of 1 MAC, 2 MAC, 3 MAC sevoflurane on intracranial pressure (ICP), mean arterial blood pressure (MABP) and heart rate (HR) in rabbits with experimental intracerebral haematoma (ICH).

MATERIAL AND METHODS

The experiments were performed in 13 adult rabbits, 3.5-4.0 kg weight. The rabbits were randomly allocated to two different groups. In group I, (n = 7), sevoflurane was administered in stepwise increasing concentrations of 2.2 vol%, 4.4 vol% and 6.6 vol%, each for a period of 15 minutes. In group II (n = 6), intracerebral haematoma was produced and subsequently sevoflurane was administered in the same manner as in group I. Ventilation parameters, inspiratory and end-tidal sevoflurane concentration, end-tidal CO2 concentration (ETCO2), HR, MABP, ICP and body temperature, measured in the nasopharynx, were monitored throughout the experiment.

RESULTS

Mean values of ETCO2 and temperature in the nasopharynx were not significantly different in both groups and remained stable in the whole observation period. In group II in all cases the evidence of intraventricular haematoma was observed. In this group mean values of ICP, MABP and HR after haematoma production were significantly higher than those in group I. Statistically significant increase of ICP was observed in 30th minute in group I, while in 35th minute in group II. In both groups a statistically significant decrease in MABP was observed from 20th minute of observation. A significant decrease in HR in both groups from 25th minute of experiment was also observed.

CONCLUSION

In conclusion it should be stressed that sevoflurane, in doses not exceeding 1 MAC, shows no significant effect on ICP and cardiovascular function in the course of intracranial haematoma.

Developmental changes of MAP2 immunoreactivity in the hippocampus proper and dentate gyrus of the rat

Microtubules are present in high concentration in the nervous system and are a prominent component of the neuronal cytoskeleton. Microtubules are composed of tubulin and variety of microtubule-associated proteins (MAPs), which have been implicated in the regulation of microtubule assembly and function. MAP2 is the most abundant of these proteins, and it has been extensively characterized in various functional and pathological conditions. In the present study the distribution of MAP2 was examined in each layer of the CA1 and CA3 regions of the hippocampus proper and dentate gyrus in rat development. A total of 40 brains at various ages starting from postnatal day (P) 0 to P90 were examined. After perfusional fixation the brains were frozen and cut on the coronal plane and stained with either cresyl violet or standard immunohistochemical methods using the anti-MAP2 antibody. MAP2 exhibited a somatodendritic pattern of localization in cells of the hippocampus. Staining was most prominent in dendrites and perikarya as well as granules surrounding cell bodies. In a newborn rat's brain immunostaining was intense in granules and faint in perikarya. Between P4 and P21 immunostaining density for MAP2 was stronger and appeared in perikarya, granules, and dendritic trees. After P21 the perikarya and dendrites of the pyramidal layer and stratum radiatum of the hippocampus proper, as well as the molecular and granular layer of dentate gyrus, showed reduced immunoreactivity. In the stratum oriens of the hippocampus and polymorphic layer of the dentate gyrus immunoreactivity was still strong until P90.

Cholinergic endings on various neurones containing calcium binding proteins and glutamic acid decarboxylase in the hippocampus of the rat

Immunohistochemical study of the cholinergic innervation of the hippocampal cells containing glutamic acid decarboxylase (GAD) and calcium binding proteins: parvalbumin (PV), calbindin D28k (CB) and calretinin (CR) was conducted on 5 adult rat brains. Analysis of sections with double immunostaining for vesicular acetylcholine transporter (VAChT; the marker of cholinergic cells, fibres and terminals) and respectively either GAD or PV, CB, CR, using confocal laser-scanning microscope shows that the intensive cholinergic innervations receive GAD, PV and CB-positive hippocampal cells. Cholinergic afferentiations of the CR-positive neurones are considerably fewer.

The influence of the intraventricular hemorrhage on the intracranial pressure and hemodynamic changes in the experimental intracerebral hemorrhage in the rabbits

The experimental model of the intracerebral hematoma in the rabbit was used for the investigation of the changes of the intracranial pressure and selected hemodynamic parameters. The study was performed on 13 adult rabbits, divided into two groups receiving 1 ml (group I--6 animals) and 2 ml (group II--7 animals) of fresh arterial blood, respectively. The monitoring of the intracranial pressure (ICP), the mean arterial blood pressure (MABP), the heart rate (HR), the end-tidal CO2 concentration (ETCO2) and the body temperature was measured every minute in the hematoma production phase and every 5 minutes for the consecutive three hours. The volume of the hematoma was calculated according to Cavalieri formula, with the use of the system for the automatic picture analysis. The mean volume of the intraparenchymal part of the hematoma in group I was higher than in the group II. However, in all the representatives of the second group the evidence of the intraventricular hemorrhage was present. The dynamics of the ICP, MABP and HR changes differed significantly in both groups during the period of the observation. On the basis of the physiological and morphological observations we conclude that the changes of ICP remain the most sensitive and valuable parameter during the early course of the intracerebral hemorrhage. Coexistence of the rapid ICP, MABP and HR changes must be always regarded as the possible sign of the intraventricular hemorrhage.

Microglial and astroglial cells in the rat paraclaustral reservoir during postnatal development: an immunohistochemical study

A immunohistochemical study of postnatal development of the paraclaustral reservoir of migrating cells in the rat brain was performed using anti-GFAP (for astroglia), ED1 and OX-42 (for microglia) antibodies. From birth to the 4th day of postnatal life most GFAP-positive cells in the paraclaustral reservoir are similar to transitional astroglia. From the end of the first postnatal week they have the morphology of mature astrocytes, although during the next week, their density was a slightly higher than in neighboring structures. On the 21st day, the morphology and density of astroglial cells in the ventral part of the external capsule did not differ from the surrounding regions. ED1/OX-42- positive microglial cells present in the paraclaustral reservoir during the first postnatal week represented ameboid microglia; their density was clearly higher than in the neighboring structures. During the second week they began to transform into ramified microglia and from the 21st day on, only OX-42 positive resting microglial cells were observed in the ventral part of the external capsule. We suggest that the paraclaustral reservoir is a place of accumulation of astroglia and microglia during brain development and may possibly serve as source of glial cells for neighboring structures. Alternatively, these glial populations may perform local developmental functions.

Immunohistochemical study of microglial and astroglial cells during postnatal development of rat striatum

The present study investigates the development of microglial and astroglial cells in the postnatal rat striatum, using immunohistochemical methods with panel antibodies that recognize macrophage antigens of unknown function--ED 1, complement type 3 receptor--OX-42 (for microglia) and glial fibrillary acidic protein (for astrocytes). On the day of birth, ED1/OX-42- immunoreactive microglial cells present in the striatum represent ameboid microglia. Between P0 and P10 we could observe the migration of ameboid microglial cells from neuroepithelial ventricular zone through internal and external capsules into the striatum. During the second postnatal week (P10, P14) a considerable decline of ameboid ED1-immunoreactive microglial cells and an increase of the number of OX-42 positive ramified cells was observed. At P21 only OX-42 positive ramified cells were observed in the whole striatum. On the day of birth, only a few GFAP-positive cells resembling radial glia were observed in the striatum. During the first postnatal week, the number of GFAP-positive cells increased significantly; they showed typical morphology of the astrocytes present in the adult animals. After P21 the final striatal population of astroglia was formed.

Expression of calbindin-D28k and parvalbumin during development of rat's basolateral amygdaloid complex

Parvalbumin and calbindin-D28k are calcium-binding proteins, which are considered to be markers for certain populations of GABAergic neurons. Their correct development in the basolateral amygdaloid complex is critical for the proper emotional functioning in adult live of human and animals. Therefore, in this paper we describe the pattern of the morphological differentiation and distribution of immunoreactive elements of the parvalbumin and calbindin-D28k in this complex on the basis of immunohistochemically stained material obtained from embryonic (E20) and postnatal (P0-P90) rat brains. Calbindin-D28k appeared early in the development, already in the prenatal life. At this time immunopositive reaction was visible only in cell bodies. However, during development the population of immunopositive neurons was divided into four types: (1) polygonal; (2) piriform-like; (3) bipolar; and (4) pyramidal-like. Two weeks after birth calbindin-D28k immunoreactivity also appeared in neuropil. First, there were visible calbindin-D28k positive fibers and granules that encircled unstained cell bodies and formed basket-like structures. Subsequently, these granules appeared along proximal parts of unstained dendrites forming, so called 'cartridges'. The distribution of calbindin-D28k positive cells during postnatal life was rather homogenous throughout whole basolateral complex. Intensity of calbindin-D28k immunoreactivity reached mature level on the 21st day after birth.The maturation pattern of parvalbumin immunopositive elements followed the same sequence as calbindin-D28k, but it started much later - since the 17th day after birth and reached mature appearance on the 30th day of life. Contrary to calbindin-D28k, parvalbumin was not homogeneously distributed in the basolateral complex. Originally, parvalbumin was restricted to the magnocellular part of basolateral nucleus but it was finally expressed also in the parvicellular part of basolateral nucleus and the dorsolateral part of lateral nucleus. The differences in development of these two calcium-binding proteins indicate that parvalbumin and calbindin-D28k play diverse roles during development and maturation of the basolateral amygdala.

The different patterns of maturation of the claustrocortical connections in a rabbit

The quantitative analysis of the claustrocortical connections labeled with the fluorescent retrograde tracer Fluoro-Gold (FG) was conducted on 90 rabbits subdivided into the following age groups (P2, P7, P14, P21, P30, P60, P90, P120, P180). The equal volumes of retrograde fluorescent tracer FluoroGold (FG) were injected into the selected regions of the motor or somatosensory cortices. The volume of the dorsal part of the claustrum, total number of projecting neurons, numerical density and percentage distribution of projecting neurons were estimated by means of the unbiased stereological methods. The claustrocortical connections both with the motor and somatosensory areas in a rabbit are established in the postnatal life. The parts of the claustrum occupied by the motor and somatosensory projection zones as well as the morphology of the cortically projecting neurons do not reveal characteristic changes during the studied period. The significant decrease of the total number and numerical density of cortically projecting neurons as well as the increase of the claustral volume may reflect the process of adjustment of the claustrum to its modulatory function upon corresponding cortical areas. The intensity of the claustral connections with the motor and somatosensory cortices reveals significant difference during the studied period, being higher for the motor projection. It may be assumed that the claustrocortical connections established before birth undergo significant quantitative changes during postnatal development.

The basolateral amygdaloid complex--its development, morphology and functions

For many years the amygdaloid body has been an object of numerous investigations on different species, because the basolateral complex, being the main part of the amygdaloid body, is regarded as "sensory input" to this structure. It plays a very important role in so called emotional memory and learning, what is particularly important in early developmental stages. Impairment at this time may cause psychiatric problems in later life, like neurosis, phobia, unconscious fear or panic attacks. Complicated functions of the basolateral complex require precise control and modulation especially in early development. In this review the morphological changes during the development and maturation will be discussed and compared with neurotransmitter as well as with the expression of the calcium binding proteins at various stages of the development.

Comparative anatomy of the claustrum in selected species: A morphometric analysis

The morphology of the claustrum was studied by stereological methods in representatives of five mammalian orders (Insectivora, Rodentia, Lagomorpha, Carnivora and Primates). In each species under study, a dorsal and a ventral part of the nucleus can be distinguished. Based on differences in shape and separation from surrounding structures, five morphological types of the claustrum occur. The claustrum of Insectivora and some rodents represents the least complicated morphological type. The nucleus is very poorly separated from the surrounding structures. The human claustrum is morphologically the most complicated, although the two above-mentioned principal divisions are apparent. The ventrally situated paraamygdalar part of the human claustrum may correspond to the endopiriform nucleus or ventral part of the claustrum of other mammals, because of its morphological characteristics and connections with the limbic system. In guinea pigs, traditionally classified as members of the Rodentia, a characteristic morphological type of the claustrum is present. This observation may support arguments questioning the current position of this species in mammalian classification. Based on stereological studies, the increase of the claustral volume that occurs with increase of the hemispheric volume is significantly smaller than the increase of the isocortical volume and larger than the increase of the allocortical volume. The increase of the volume of the dorsal and ventral parts of the claustrum does not differ significantly in the species under study. Neurons of the claustrum represent differentiated morphology. The numerical density of neurons in the dorsal part of the claustrum is significantly higher than in the ventral one. Differences in the morphology and cellular structure of the two parts of the claustrum may suggest differences in function of the two parts of the nucleus, most probably concerned with transfer of information among various cortical regions. Changes in the claustrum, a cortico-related structure, that occur with increased brain volume, may suggest that its development is less dynamic than that of the isocortex.

The connections of the endopiriform nucleus with the insular claustrum in the rat and rabbit

The connections between two parts of the claustrum in the rat and rabbit were studied using the highly fluorescent lipophilic carbocyanine dye (Dil). After the application of Dil crystal into the endopiriform nucleus, labeled fibers in the insular claustrum were observed in its part directly neighboring the insular cortex and capsula externa. Additionally, numerous projections into the piriform, insular and entorhinal cortices were present. The presence of connections between the endopiriform nucleus and insular claustrum suggests its role concerned with the processes taking part in the allocortical regions as well as in the limbic system.

Qualitative and quantitative differences in the motor and somatosensory cortical projections of the rat claustrum--combined retrograde transport and stereological studies

Using axonal retrograde tracing, combined with morphometric analysis, we compared the distribution and number of claustral neurons projecting to the motor and somatosensory cortical areas in the Wistar rat. Comparable volumes of the retrograde tracer Fluoro-Gold, were injected into the motor or somatosensory cortices. Injections into these areas resulted in labeling of neurons along the entire length of the claustrum. Neurons retrogradely labeled after injection into the motor cortex prevailed in the anterior part of the claustrum, whereas those projecting to the somatosensory cortex predominated in the central part. The mean number of claustral neurons retrogradely labeled after tracer injections into the motor cortex significantly outnumbered that from the somatosensory cortical area (p < 0.01). Similarly, the mean value of the numerical density of the retrogradely labeled neurons was significantly higher for the motor projection zone in the claustrum, than for the somatosensory projection zone (p < 0.001). The contralateral claustral projections, both into the motor and somatosensory cortices, were considerably lower in number than the ipsilateral ones. These findings indicate that: (1) the claustral projections to the various cortical regions seem to be differentiated (2) the distribution of claustral neurons projecting to the motor and somatosensory neocortical areas shows an anteroposterior gradient, (3) the claustrum of the rat appears to be more closely related to the motor than to the somatosensory system, (4) the rat claustrum seems to function more as a satellite than a relay structure in relationship to the cerebral cortex.

Claustrocingulate connections in the rabbit and rat--a stereological study

Unbiased stereological methods were used for estimating the numerical density and the total number of claustral neurones projecting to the cingulate cortex in rabbit and rat. In rat the numerical density of neurones projecting to the retrosplenial granular cortex (RSG) differed significantly from those projecting to the retrosplenial agranular (RSA) and cingulate (Cg) cortices while in rabbit the numerical densities of retrogradely labelled neurones in the claustrum following injections into various areas of the cerebral cortex did not differ significantly. The total number of retrogradely labelled neurones in the claustral limbic zones did not differ significantly in both species. The quantitative analysis of claustral zones projecting to a different cingulate cortex area, both in rabbit and rat, reveals that each of these zones is rather homogeneous.

The combined retrograde transport and unbiased stereological study of the claustrocortical connections in the rabbit

The quantitative analysis of the claustrocortical connections in the rabbit, labeled with the fluorescent retrograde tracer Fluoro-Gold (FG), was conducted by means of unbiased stereology. The FG was injected into selected regions of the motor, somatosensory, auditory and visual cortices and then a comparison of the various claustrocortical projections was carried out. This was achieved by comparing (1) the numerical densities of projecting neurones for each claustral projection zone and (2) the distribution of the labeled neurones throughout the rostro-caudal extent of the claustrum. No significant differences between the numerical densities of labeled neurones in the various projection zones are reported. The motor and primary somatosensory projections dominated in the anterior and central parts of the claustrum, whereas the secondary somatosensory, auditory and visual projections--in the posterior part. The difference in the distributions was significant (p < 0.001). Summarizing, the cortical projections in the claustrum, although varying topographically, do not reveal a quantitative differentiation. This may speak in favour of the integrative and modulating function of this structure in relationship to the neocortex.

The shape of the inferior horn of the lateral ventricle in relation to collateral and occipitotemporal sulci

The shape of the inferior horn of the lateral ventricle has been investigated in 100 (50 right and 50 left) human brain hemispheres which were fixed in 40% formaldehyde solution and cut frontally. It has been found that the shape of the inferior horn depends on the course and depth of the collateral and occipitotemporal sulci. In most cases a part from two main ventricular surfaces: the hippocampal and superolateral, there is one surface more, either the inferior-collateral eminence (Type I--97% of cases in the posterior part of the inferior horn, 49%--in the middle and 42%--in the anterior part) or the inferolateral, adjecent to the occipitotemporal sulcus (Type II--0%, 26% and 35%, respectively). In a few cases both collateral eminence and inferolateral surface were present (Type III--3%, 2% and 6% respectively). In type IV neither collateral eminence nor the inferolateral surface appeared (0%, 23%, 17% respectively). The authors suggest to designate the inferolateral surface, not mentioned in the literature, as the occpitotemporal eminence (of the inferior horn).

Expression and distribution of various antigens of developing microglial cells in the rat telencephalon

The distribution of microglia during the early stages of postnatal development in the rat was studied on rat brain from day of birth to postnatal day 90 (P90), using immunohistochemical methods with a panel of monoclonal antibodies that recognized the complement type 3 receptor (OX-42), macrophage antigen of unknown function (ED1), and the major histocompatibility complex (MHC) class I (OX-18) or class II (OX-6) antigens. Starting from the day of birth, ameboid microglia can be differentiated with positive immunoreactivity to OX-42, OX-18, and ED1. Labeled cells were localized mainly in the developing white matter. After P21, only positive reaction to OX-42 was present, and those cells had the typical morphology of the resting microglial cells that were located either in the white or grey matter. The changes in the appearance of different antigens are correlated with the morphological differentiation and transformation of ameboid microglial cells that are to become ramified microglia, present in the adult animals.

Measurements of the Obersteiner-Redlich zone of the vagus nerve and their possible clinical applications

The aim of our study was to describe anatomical variability of the root entry zone (REZ), also called the Obersteiner-Redlich zone, that represents the "junction zone" of glia and Schwann sheath of the cranial nerves. This zone has some clinical implications. The pulsatile compression of REZ by a vessel may produce clinical symptoms, such us trigeminal neuralgia, hemifacial spasm, glossopharyngeal neuralgia torticollis spasmodicus or even symptoms of essential hypertension when a vascular cross compression of REZ of a left vagus nerve is present. The vessel--cranial nerve contact in the skull base cysterns may be visualized in radiologic examinations, most accurately in magnetic resonance imaging. Because, we cannot distinguish the REZ from the rest of the vagus nerve in radiologic examinations we decided to measure the length of its REZ. The microanatomical study of the length of REZ zone of the vagus nerve was performed on 21 nerves taken from 17 human brain stems (12 men, 5 women, 14 left, 7 right), fixed with 8% buffered formalin solution. Paraffin embedded tissue was cut into 10-micron-thick sections parallel to the nerve longitudinal axis and stained with hematoxilin & eosin. Each of the nerves showed the presence of a zone of oligodendrocyte myelination, mean length 2 +/- 0.3 mm. In 17 nerves the transitional zone formed a cone-like process, in 4 nerves was shaped irregularly. The length of REZ (oligodendrocyte myelination plus "glial dome") had the mean length 3.5 +/- 0.9 mm.

The piriform cortex and the endopiriform nucleus in the rat reveal generally similar pattern of connections

The afferent and efferent connections of the piriform cortex and the endopiriform nucleus in the rat were studied by the method of axonal transport of two fluorescent tracers: Fluoro-Gold and Fluoro-Ruby. The results indicate that both structures possess not only the connections with the olfactory system, but also the reciprocal connections with the limbic system (entorhinal cortex, amygdaloid body), thalamus (mediodorsal and midline nuclei), extrapyramidal system (ventral part of the nucleus accumbens). The topographic differences in the organization of the association connections between the anterior and posterior parts of the piriform cortex are reported. Additionally, the reciprocal and relatively numerous connections between the endopiriform nucleus and the piriform cortex may result in their modulatory function, which in some pathological circumstances may have a critical significance in epileptogenesis.