Minocycline but not valproic acid influence the density of NogoA-immunoreactive neurons in the hilus of the dentate gyrus of the rats subjected to intracerebral haematoma

Intracerebral haemorrhage is a devastating neurological disease with high mortality rate and poor prognosis. The most prominent manifestation of the disease arethe movement disorders, but many patients also suffer from cognitive impairment. Taking into account vulnerability of the neurons located within the hilus of the dentate gyrus (HDG) to many brain insults we decided to study the effectof experimentally induced intracerebral haematoma on density of neurons expressing NogoA protein in HDG. In addition, we studied how administration of valproic acid and minocycline, the two drugs generally believed to be neuroprotective agents, influences the density of these neurons. Our study revealed that 4 weeks after intracerebral haematoma induction, minocycline and valproic acid treatment increased the densities of NogoA-ir neurons in the hilus of contralateral dentate gyrus once the data were compared to ipsilateral hemispheres within the same group. The analysis of contralateral hemisphere data, however, revealed increased densities of NogoA-positive neurons in haematoma and valproic acidtreated animals when compared to contralateral hemispheres of control animals.The administration of minocycline was, however, able to alleviate this increase.These changes may influence the haematoma-induced reorganisation of neuronal circuitries in the dentate gyrus

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

Fluoride alters type I collagen expression in the early stages of odontogenesis

Fluoride alters the expression and post-translational modifications of extracellular matrix proteins in dentin. The aim of our study was to determine the effects of fluoride on type I collagen expression during the early stages of tooth germ development in rats. Pregnant dams were divided into three groups and fed a standard diet. From the fifth day of pregnancy the three groups received tap water with, respectively, trace amounts of fluoride (C), a low fluoride concentration (FL) or and a high fluoride concentration (FH). Changes in type I collagen expression and distribution were evaluated. The expression of type I collagen was restricted to the extracellular spaces of cells of mesenchymal origin. In the youngest animals the most intense immunoreactivity for type I collagen was detected in predentin of the FL group. Although the intensity of immunostaining increased in proportion to the age of the animals, the largest increase in the groups investigated was detected in the FL group. We concluded that a low concentration of fluoride can act as a stimulator of type I collagen deposition in the extracellular matrix of dentin, while high concentrations of fluoride have an opposite effect, acting as an inhibitor of type I collagen formation in dentin

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

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

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

Apoptosis in the course of experimetal intracerebral haemorrhage in the rat

Intracerebral haematoma was produced in 25 adult rats by infusion of 100 &#181;l of autologous blood into the striatum. The animals&#8217; 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

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 l, complement type 3 receptor- OX-42 (for microglia) and glial fibrillary acidic protein (for astrocytes). On the day of birth, EDl/OX-42- immunoreactive microglial cells present in the striatum represent ameboid microglia. Between PO 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 (PIO, P14) a considerable decline of ameboid EDl-immunoreactive microglial cells and an increase of the number of OX-42 positive ramified cells were 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 striatium. 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 P22 the final striatal population of astroglia was formed