In acute experimental autoimmune encephalomyelitis, infiltrating macrophages are immune activated, whereas microglia remain immune suppressed.

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS) characterized by loss of myelin accompanied by infiltration of T-lymphocytes and monocytes. Although it has been shown that these infiltrates are important for the progression of MS, the role of microglia, the resident macrophages of the CNS, remains ambiguous. Therefore, we have compared the phenotypes of microglia and macrophages in a mouse model for MS, experimental autoimmune encephalomyelitis (EAE). In order to properly discriminate between these two cell types, microglia were defined as CD11b(pos) CD45(int) Ly-6C(neg) , and infiltrated macrophages as CD11b(pos) CD45(high) Ly-6C(pos) . During clinical EAE, microglia displayed a weakly immune-activated phenotype, based on the expression of MHCII, co-stimulatory molecules (CD80, CD86, and CD40) and proinflammatory genes [interleukin-1ß (IL-1ß) and tumour necrosis factor- α (TNF-α)]. In contrast, CD11b(pos) CD45(high) Ly-6C(pos) infiltrated macrophages were strongly activated and could be divided into two populations Ly-6C(int) and Ly-6C(high) , respectively. Ly-6C(high) macrophages contained less myelin than Ly-6C(int) macrophages and expression levels of the proinflammatory cytokines IL-1ß and TNF-α were higher in Ly-6C(int) macrophages. Together, our data show that during clinical EAE, microglia are only weakly activated whereas infiltrated macrophages are highly immune reactive.

Novel inhibitors of the Plasmodium falciparum electron transport chain.

Due to an increased need for new antimalarial chemotherapies that show potency against Plasmodium falciparum, researchers are targeting new processes within the parasite in an effort to circumvent or delay the onset of drug resistance. One such promising area for antimalarial drug development has been the parasite mitochondrial electron transport chain (ETC). Efforts have been focused on targeting key processes along the parasite ETC specifically the dihydroorotate dehydrogenase (DHOD) enzyme, the cytochrome bc 1 enzyme and the NADH type II oxidoreductase (PfNDH2) pathway. This review summarizes the most recent efforts in antimalarial drug development reported in the literature and describes the evolution of these compounds.

In vitro ictogenesis and parahippocampal networks in a rodent model of temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is a chronic epileptic disorder involving the hippocampal formation. Details on the interactions between the hippocampus proper and parahippocampal networks during ictogenesis remain, however, unclear. In addition, recent findings have shown that epileptic limbic networks maintained in vitro are paradoxically less responsive than non-epileptic control (NEC) tissue to application of the convulsant drug 4-aminopyridine (4AP). Field potential recordings allowed us to establish here the effects of 4AP in brain slices obtained from NEC and pilocarpine-treated epileptic rats; these slices included the hippocampus and parahippocampal areas such as entorhinal and perirhinal cortices and the amygdala. First, we found that both types of tissue generate epileptiform discharges with similar electrographic characteristics. Further investigation showed that generation of robust ictal-like discharges in the epileptic rat tissue is (i) favored by decreased hippocampal output (ii) reinforced by EC-subiculum interactions and (iii) predominantly driven by amygdala networks. We propose that a functional switch to alternative synaptic routes may promote network hyperexcitability in the epileptic limbic system.

Activity and expression of nitric oxide synthase in rat bladder after sacral neuromodulation.

The aim of our study is to investigate the effects of chronic sacral neuromodulation on Nitric Oxide (NO) metabolism in the rat bladder. 26 female Sprangue-Dawley rats were considered: group I, normal control rats; group II, a sham treatment, in whom catheters for electrical stimulation were placed in the S1 foramen bilaterally and left in place for 21 days, without performing neuromodulation; group III in whom electrical sacral neuromodulation was performed for 21 days. Finally a cystectomy was performed and the bladder biopsy specimens were sent for immunostaining with n-NOS and i-NOS. Morphological and immunohistochemical analysis was carried out, and evaluated in urothelial cells, endothelial cells and muscle fibers of the muscularis propria. Differences between the 3 groups were analyzed by Student Newman-Keuls test. We could observe that urothelial and endothelial i-NOS (37.00+/-4.69 and 59.00+/-7.42 respectively) and urothelial n-NOS (36.80+/-7.85) expression are significantly increased in neuromodulated rats, compared to groups 1 and 2 (p<0.005). In conclusion, the increase of i-NOS expression on endothelial cells after sacral neuromodulation could be in some way related to angiogenetic responses in the microvascular structures; the increase of n-NOS and i-NOS expression on urothelial cells can suggest that NO is able to influence the plasticity of bladder response, inducing the release of messengers within the urothelium. This study can therefore improve our understanding of the mechanisms of sacral neuromodulation on chronic bladder dysfunction; further studies will need to better demonstrate the role of angiogenesis in the bladder after sacral neuromodulation and to investigate the effects of neuromodulation in rats with chronically induced bladder dysfunction.

Antiepileptic drugs and muscarinic receptor-dependent excitation in the rat subiculum.

Field and intracellular recordings were made in an in vitro slice preparation to establish whether the antiepileptic drugs topiramate and lamotrigine modulate cholinergic excitation in the rat subiculum. Bath application of carbachol (CCh, 70-100microM) induced: (i) spontaneous and synchronous field oscillations (duration=up to 7s) that were mirrored by intracellular depolarizations with rhythmic action potential bursts; and (ii) depolarizing plateau potentials (DPPs, duration=up to 2.5s) associated with action potential discharge in response to brief (50-100ms) intracellular depolarizing current pulses. Ionotropic glutamatergic receptor antagonists abolished the field oscillations without influencing DPPs, while atropine (1microM) markedly reduced both types of activity. Topiramate (10-100microM, n=8-13 slices) or lamotrigine (50-400microM, n=3-12) decreased in a dose-dependent manner, and eventually abolished, CCh-induced field oscillations. During topiramate application, these effects were accompanied by marked DPP reduction. When these antiepileptic drugs were tested on DPPs recorded in the presence of CCh+ionotropic glutamatergic and GABA receptor antagonists, only topiramate reduced DPPs (n=5-19/dose; IC(50)=18microM, n=48). Similar effects were induced by topiramate during metabotropic glutamate receptor antagonism (n=5), which did not influence DPPs. Thus, topiramate and lamotrigine reduce CCh-induced epileptiform synchronization in the rat subiculum but only topiramate is effective in controlling DPPs. We propose that muscarinic receptor-mediated excitation represents a target for the action of some antiepileptic drugs such as topiramate.

In melanoma changes of immature and mature dendritic cell expression correlate with tumor thickness:an immunohistochemical study.

Cells with a dendritic morphology and/or expression of dendritic cell (DC) markers have been repeatedly described in several human tumors, but the distribution and density of melanoma-associated DCs have not yet been reported. The aim of the present study is to analyze the density and topographical distribution of melanoma-associated DCs and their relation with CD3(+), CD4(+) and CD8(+) T lymphocytes in forty cases of cutaneous human melanoma. In melanocytic tumours different pools of DCs were recognised in the epidermis and in the dermis, particularly in intimate relation with lymphocyte clusters inside the melanocytic proliferation, and more often at the edges of tumours. The number of Langerin-positive DCs showed an inverse correlation with tumour depth (correlation coefficient r= -0.59, P=0.0001) and was significantly lower in thick melanomas compared to thin and intermediate ones (P<0.0005). The density of CD83(+) DCs was significantly lower in thick melanomas compared to thin and intermediate ones (P<0.009). A significant correlation was found between the density of the two DCs subsets (r=0.57, p<0.0001). The number of CD3(+) lymphocytes was inversely correlated to the depth of infiltration (r=-0.596, P<0.0001): melanoma cases with II-III Clark level showed a higher T lymphocyte mean density compared to cases with IV-V Clark level (P<0.0001). T lymphocyte density was significantly lower in thick melanomas compared to thin and intermediate melanomas (P<0.0005). In conclusion, our study indicates a progressive loss of DCs and T lymphocytes in the neoplastic progression of melanomas; further identification of the molecular pathways involved in the functional impairment of these immunitary cells may lead to new immunotherapeutic approaches for melanoma patients that would improve the clinical outcome of the patients.

Mitochondrial changes induced by natural and synthetic asbestos fibers: studies on isolated mitochondria.

Asbestos fibers, such as chrysotile and crocidolite, are known to have cytotoxic effects on different cell types. In vivo exposure to asbestos fibers can induce both fibrotic and malignant lung diseases , however, the mechanisms linking exposure to the subsequent development of the diseases are unknown. Numerous investigations suggest the involvement of reactive oxygen species (ROS). ROS are known to damage biological macromolecules including proteins, cell membrane lipids and nucleic acids; alterations of these essential cellular components can alter cell function and can drive the cell to neoplastic transformation or to cell death. Because the mitochondrial respiratory chain is an important source of ROS and RNS (reactive nitogen species) in the cells, we have investigated the effects of aqueous extracts of asbestos (natural and synthetic) fibers on some mitochondrial activities. Our data show that crocidolite fibers release substances in solution that may interfere directly with the mitochondrial cytochrome oxidase complex. Moreover, the calcium ions released from these fibers induce opening of the permeability transition pore of the inner membrane leading to a possible cytotoxic effect due to the release of apoptotic factors normally localized in the mitochondrial intermembrane space. In addition, crocidolite extracts enhance the mitochondrial production of ROS. No significant biochemical effects are exerted by chrysotile, either natural or synthetic, on isolated mitochondria. Nevertheless, all asbestos fibers tested induce morphological alterations visualized by transmission electron microscopy and morphometric analysis.

In vitro study of biofunctional indicators after exposure to asbestos-like fluoro-edenite fibres.

The in vitro biological response to fluoro-edenite (FE) fibres, an asbestos-like amphibole, was evaluated in lung alveolar epithelial A549, mesothelial MeT-5A and monocyte-macrophage J774 cell lines. The mineral has been found in the vicinity of the town of Biancavilla (Catania, Sicily), where an abnormal incidence of mesothelioma has been documented. Cell motility, distribution of polymerized actin, and synthesis of vascular endothelial growth factor (VEGF) and of beta-catenin, critical parameters for tumour development, progression and survival, were investigated in A549 and MeT-5A cells exposed to 50 microg/ml FE fibres for 24 hr and 48 hr. The levels of cyclooxygenase (COX-2) and prostaglandin (PGE2), two molecules involved in cancer pathogenesis by affecting mitogenesis, cell adhesion, immune surveillance and apoptosis, were measured in J774 cells treated with FE fibres under the same experimental conditions. Finally, FE fibres were studied by SEM and EDS analysis to investigate their chemical composition. Exposure of A549 and MeT-5A cells to FE fibres affected differentially phalloidin-stained cytoplasmic F-actin networks, cell motility and VEGF and beta-catenin expression according to the different sensitivity of the two cell lines. In J774 cells it induced a significant increase in COX-2 expression, as assessed by Western blot analysis, and in the concentration of PGE2, measured in culture media by ELISA. SEM-EDS investigations demonstrated two types of FE fibres, edenite and fluoro-edenite, differing in chemical composition and both recognizable as calcic amphiboles. Fibre width ranged from less than 1 microm (prevalently 0.5 microm) to 2-3 microm (edenite) up to several microm (fluoro-edenite); length ranged from about 6 to 80 microm (edenite) up to some hundred microm (fluoro-edenite). Results provide convincing evidence that FE fibres are capable of inducing in vitro functional modifications in a number of parameters with crucial roles in cancer development and progression. Inhaled FE fibres have the potential to induce mesothelioma, even though their ability to penetrate lung alveoli depends on their aerodynamic diameter.

Increased VEGF165 expression in HCT116 colon cancer cells after transient transfection with a GFP vector encoding HIF-1 gene.

Hypoxia occurs in most solid tumors as a result of inefficient vascular development and/or abnormal vascular architecture. During hypoxia, HIF-1alpha acts as the primary transcription factor functioning to activate multiple target genes, including vascular endothelial growth factor (VEGF). Several studies have demonstrated that in tumors HIF-1alpha mediates VEGF protein expression at the transcription level. We aimed to establish whether HCT116 colon cancer cell VEGF expression is regulated by HIF-1 levels after transient transfection with a GFP vector encoding the HIF-1alpha gene. HCT116 cell VEGF expression were therefore assayed by immunohistochemistry and ELISA. After transfection with phMGFP-HIF-1alpha, VEGF immunostaining was significantly increased in transfected cells as compared with untransfected HCT116 cells (p = 0.024, Student's t test); culture media VEGF levels assayed by ELISA were also significantly increased in transfected cells (p = 0.008, Student's t-test). These data suggest that HIF-1alpha may play an important role in colon cancer angiogenesis, both as a biomarker of metastatic potential and as a novel target for gene therapy.

Synaptic hyperexcitability of deep layer neocortical cells in a genetic model of absence seizures.

We used sharp-electrode, intracellular recordings in an in vitro brain slice preparation to study the excitability of neocortical neurons located in the deep layers (>900 microm from the pia) of epileptic (180-210-days old) Wistar Albino Glaxo/Rijswijk (WAG/Rij) and age-matched, non-epileptic control (NEC) rats. Wistar Albino Glaxo/Rijswijk rats represent a genetic model of absence seizures associated with generalized spike and wave (SW) discharges in vivo. When filled with neurobiotin, these neurons had a typical pyramidal shape with extensive apical and basal dendritic trees; moreover, WAG/Rij and NEC cells had similar fundamental electrophysiological and repetitive firing properties. Sequences of excitatory postsynaptic potentials (EPSPs) and hyperpolarizing inhibitory postsynaptic potentials (IPSPs) were induced in both the strains by electrical stimuli delivered to the underlying white matter or within the neocortex; however, in 24 of 55 regularly firing WAG/Rij cells but only in 2 of 25 NEC neurons, we identified a late EPSP that (1) led to action potential discharge and (2) was abolished by the N-methyl-D-aspartate (NMDA) receptor antagonist 3,3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonate (20 microM; n = 8/8 WAG/Rij cells). Finally, we found that the fast and slow components of the stimulus-induced IPSPs recorded during the application of glutamatergic receptor antagonists had similar reversal potentials in the two strains, while the peak conductance of the fast IPSP was significantly reduced in WAG/Rij cells. These findings document an increase in synaptic excitability that is mediated by NMDA receptors, in epileptic WAG/Rij rat neurons located in neocortical deep layers. We propose that this mechanism may be instrumental for initiating and maintaining generalized SW discharges in vivo.

VEGF is likely a key factor in the link between inflammation and angiogenesis in psoriasis: results of an immunohistochemical study.

Psoriasis is a chronic skin disease, characterized by epidermal hyperplasia, inflammation, angiogenesis and vascular remodelling. An immunohistochemical study on fifteen cryosections of psoriatic skin was performed using antibodies against VEGF, HIF1-alpha, CD34, Factor VIII, MMP-2, MMP-9, TIMP-1 and TIMP-2. Psoriatic skin showed a diffuse VEGF positive staining (13.15+/-6.6), while no expression was observed in normal epidermis. No or faint HIF-1alpha immunostaining was detected in healthy skin, while in psoriatic skin HIF-1alpha was diffusely expressed. A positive correlation between HIF-1alpha and VEGF was reported in psoriatic skin (r= 0.644; p=0.010). In psoriatic sections CD34 expression was significantly higher in respect to control skin (19.15+/-12.61 vs 3.0+/-0.23; p= 0.04), factor VIII immunostaining also demonstrated a significant increased development of the microvasculature in comparison with healthy skin (18.39+/-8.16 vs 7.4+/-0.20; p= 0.033). Total MMP-2 expression of healthy skin (30+/-2.26) was significantly lower in respect to the MMP-2 psoriatic skin (71.5+/-4.13; p= 0.0001) and a positive correlation was observed between VEGF and MMP-2 in psoriatic patients (r= 0.688; p= 0.046). In psoriatic skin MMP-9 expression was significantly increased in comparison to control skin (31+/-3.3 vs 8+/-6.1; p=0.007). All cases of psoriatic skin tissue showed that TIMP-2 and TIMP-1 expression statistically decreased in psoriatic skin (respectively 11+/-1.2 and 12+/-1.5) in comparison with healthy skin (respectively 15+/-3.2 and 53+/-3.8; p=0.0001). In conclusion, we observed that VEGF overexpression correlated with HIF-1alpha and MMP-2 expression, underlining the role of VEGF in psoriasis as a key factor in the link between inflammation and angiogenesis.

Establishment of a Ph1-positive human cell line (BV173).

A new cell line (BV173) derived from a patient with Philadelphia chromosome (Ph1)-positive acute leukemia was compared with the Ph1-positive K562 and NALM-1 lines, which display the phenotypic characteristics of erythroid and pre-B cells, respectively. BV173 cells retained the Ph1 chromosome and had the morphologic and cytochemical features of undifferentiated blast cells. They lacked the membrane characteristics of mature B- or T-lymphocytes and did not react with monoclonal antibodies to the myelomonocytic cell lineage. Although they reacted with anti-glycophorin A antiserum, they failed to produce hemoglobin after butyric acid treatment. This line was similar to NALM-1 in that it bore common acute lymphoblastic leukemia antigen and la-like antigen, reacted with monoclonal antibodies directed against early stages of hematopoietic cell differentiation, and presented the nuclear enzyme terminal deoxynucleotidyl transferase. However, it differed from NALM-1 because it did not express cytoplasmic IgM, a marker of pre-B-cells. The new line can be considered a clonal expansion of leukemia cells blocked at an earlier differentiation stage than that for the other Ph1-positive cell lines.

Resin-based dentin restorative materials under accelerated ageing: bio-functional behavior.

OBJECT: The aim of the present study was the evaluation of the effect of different polishing and finishing procedures on Filtek Z250 FZ ESPE restorative material. Particularly, the consequence of artificial aging (UV-irradiation) on this resin-based dental material was investigated determining also its outcome on cell behavior. METHODS: 96 specimens of restorative material were prepared using a light emitting diode curing unit and randomly divided into four finishing and polishing groups: (I) No treatment (FZ); (II) Identoflex rubbers (ID); (III) Enhance System (EN) and (IV) Sof-Lex Pop-on XT discs (SF). The surface morphology of native and artificially aged materials was assessed with Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). FTIR and biological (biocompatibility and bacterial adhesion) analyses were also performed. RESULTS: Among all, the ID procedure represented an acceptable compromise for efficiency of polymerization and biocompatibility both before and after artificial ageing. SF and EN techniques showed better interactions with the biological environment. CONCLUSION: UV artificial ageing of the tested specimens has shown an acceleration of the surface degrading processes, favoring a possible decrease in the mechanical properties and the release of toxic free radicals. Finishing and polishing procedure seemed to affect the photodegrading pathways, even though no differences among the techniques were observed. As the cytotoxicity of materials undergoing accelerated aging is relevant, further improvement of dental restorative materials are required to limit the long-term biological damage.

In vitro evaluation of bio-functional performances of Ghimas titanium implants.

Titanium is the most widely used material for dental implants. The natural formation, in presence of oxygen, of different oxide films (passivation films) is correlated to titanium implant biocompatibility, resistance to corrosion and is responsible for implant bacteriostatic action. Surface roughness is another surface property of Ti-implants that, affecting implant-to-bone contact, improves integration. In the present study data concerning composition, surface roughness and biocompatibility of Ghimas implants and mini-implants undergoing sandblasting with Calcium Magnesium Carbonate (CaMg(CO3)2) are reported. AFM, SEM/EDX, XRD analyses and morpho-functional tests (MTT and ALP) were performed. Cell actin cytoskeletal modification (fluorescence phalloidin staining) was also observed with confocal laser microscopy (CLSM). Data related to surface geometry and chemical properties, associated with evidence of high purity of all the tested materials (XRD and EDX), highlighted the elevated biocompatibility of tested implants and mini-implants. CLSM investigation confirmed osteoblast features of an active cell behavior able to fit cell to chemico-mechanical stimuli present at the bone/implant interface and suggests an effective implant/alveolar bone integration in vivo.

A biochemical-morphological study on microvillus plasma membrane development.

The microvillus plasma membrane of the human placental syncytiotrophoblast at term has been extensively studied, while little is known about the characteristics of its development. The aim of the present work was to compare functional and structural properties of this membrane at early and term gestational age. Ten normal term placentas (40 weeks) and ten placentas at 10 weeks of gestational age were studied. The Na+/K+-ATPase activity is significantly decreased in the syncytiotrophoblast plasma membrane obtained from term placentas as compared to the early ones, with significant variation of maximum velocity (Vmax). The microviscosity, evaluated by the P parameter of DPH and Sn parameters of 5- and 16-NS, is increased in the term placentas compared to the early placentas. This alteration is accompanied by an increased cholesterol to phospholipids ratio in term placentas, while there is a decreased unsaturated to saturated fatty acid ratio. As follows from morphological studies, an increased mean diameter in the E face was observed in the term placenta with respect to the early placenta. The distribution factor DF, which indicates the particle aggregation state, decreased in the E face in the term placenta as compared to the early one. The present biochemical morphological study shows that a deep modification of the membrane is at the basis of the syncytiotrophoblast plasma membrane development.

HA/alginate hybrid composites prepared through bio-inspired nucleation.

Poorly crystalline apatite has been directly nucleated on self-assembling alginate chains by neutralization synthesis to obtain a biomimetic artificial bone-like composite. It has been observed that in preparing HA/alginate composites, Ca2+ ions present on the apatitic surface cross-link the alginate chains to produce a material with different morphology and thermal stability, both functions of the HA/alginate weight ratio. In vitro tests were performed on different samples in terms of both the HA/alginate ratio and synthesis temperature. All the samples were cultured for seven days with MG63 osteoblast-like cells and then underwent morphological and biochemical analyses (MTT and ALP tests). Scaffolds showed a different solubility into the culture media, which was related to the temperature of synthesis and to the HA/alginate ratio. All our data confirm the ability of the tested materials to favour cell growth and to maintain their osteoblastic functionality, at least during the examined period.

High-resolution 3D scaffold model for engineered tissue fabrication using a rapid prototyping technique.

Rapid prototyping, automatic image processing (computer-aided design (CAD)) and computer-aided manufacturing techniques are opening new and interesting prospects for medical devices and tissue engineering, especially for hard tissues such as bone. The development of a bone high-resolution scaffold prototype using these techniques is described. The results testify to the fidelity existing between microtomographic reconstruction and CAD. Furthermore, stereolithographic manufacturing of this scaffold, which possesses a high degree of similarity to the starting model as monitored by morphological evaluations (mean diameter 569 +/- 147 microm), represents a promising result for regenerative medicine applications.

Cell dynamics in the correct control of bone metabolism using natural treatments.

The present study was undertaken in order to assess the efficacy of a commercial product containing calcium and silicon (Osteosil-Calcium) on cell metabolism. MG-63 osteblast-like cells were cultured in the presence of three different drug concentrations (10, 5 and 2.5 microg/mL). Either serum-free culture and standard culture with serum were investigated. Morpho-functional tests (MTT and ALP), scanning electron microscopy (SEM), microanalysis (EDAX) and time-lapse video microscopy were performed. Cell actin cytoskeletal modification with fluorescence phalloidin staining was also tested. Our data show the in vitro functional efficacy of Osteosil-Calcium on MG63 cell viability and ALP production. This study demonstrates its positive effect on the metabolism of the single cell and suggests wider uses of this drug in health protection and or in Regenerative Medicine therapies which are currently applied to the elderly.

Indole-pyruvic acid, a tryptophan ketoanalogue, antagonizes the endocrine but not the behavioral effects of repeated stress in a model of depression.

Increased glucocorticoid secretion is frequent in mood disorders and is normalized by long-term antidepressant therapy. Many antidepressants act by increasing central serotonin transmission. We investigated the effects of a serotonin precursor, indole-pyruvic acid (IPA), in an animal model of depression based on repeated exposure to unpredictable stress. Rats were divided in groups, and IPA (20 mg/kg), the tricyclic antidepressant imipramine (IMI) (5 mg/kg), or vehicle was administered daily during 3 weeks of repeated exposure to various stressors according to the procedure described by Katz et al [Katz RJ, Roth KA, Carroll BJ (1981): Neurosci Biobehav Rev 5:247-251]. After treatment, rats were evaluated for stress-induced exploratory behavior and killed 24 hr later. Serum corticosterone levels and glucocorticoid receptor (GR) immunoreactivity (IR) in the nuclei of neurons located in the hippocampal subregion CA1 were also measured. Rats exposed to repeated stress showed a lower exploratory behavior score (p < 0.01), higher basal corticosterone levels (p < 0.01), and stronger GR IR in the hippocampus (p < 0.05) than control rats. All of these effects were antagonized by IMI treatment. IPA administration did not affect the behavioral response induced by repeated stress (p < 0.01) but normalized serum corticosterone levels. In addition, IPA treatment produced a decrease in GR IR (p < 0.05 versus control group) that was not modified by exposure to repeated stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Age-related alterations in tanycytes of the mediobasal hypothalamus of the male rat.

By means of semiquantitative immunocytochemistry, possible age-related changes in dopamine and cyclic AMP-regulated phosphoprotein mr 32 (DARPP-32) and glial fibrillary acidic protein (GFAP) immunoreactivities (IR) were investigated in tanycytes of the arcuate nucleus. These two markers showed opposite changes during aging. DARPP-32 IR decreased by around 70%, whereas GFAP IR increased by around 300% in 24-month-old vs. 3-month-old rats. These changes were accompanied by a progressive loss in the number of tanycytes, measured by counting of their long processes in the arcuate nucleus. No significant age-related change was observed either in GFAP IR in astrocytic populations of the mediobasal hypothalamus or in tyrosine hydroxylase IR in dopaminergic neurons of the dorsal arcuate nucleus. These observations indicate that the tanycytic population of the arcuate nucleus undergoes important modifications during aging, which include cell loss, impairment in the intracellular signalling cascade linked to DARPP-32, and hypertrophy. These changes may be related to the alterations in the neuroendocrine systems known to occur during aging.