Ryszard Wiaderkiewicz

Nesfatin-1, a unique regulatory neuropeptide of the brain

Nesfatin-1, a newly discovered NUCB2-derived satiety neuropeptide is expressed in several neurons of forebrain, hindbrain, brainstem and spinal cord. This novel anorexigenic substance seems to play an important role in hypothalamic pathways regulating food intake and energy homeostasis. Nesfatin-1 immunoreactive cells are detectable in arcuate (ARC), paraventricular (PVN) and supraoptic nuclei (SON), where the peptide is colocalized with POMC/CART, NPY, oxytocin and vasopressin. The nesfatin-1 molecule interacts with a G-protein coupled receptor and its cytophysiological effect depends on inhibitory hyperpolarization of NPY/AgRP neurons in ARC and melanocortin signaling in PVN. Administration of nesfatin-1 significantly inhibits consumatory behavior and decreases weight gain in experimental animals. These recent findings suggest the evidence for nesfatin-1 involvement in other important brain functions such as reproduction, sleep, cognition and anxiety- or stress-related responses. The neuroprotective and antiapoptotic properties of nesfatin-1 were also reported. From the clinical viewpoint it should be noteworthy, that the serum concentration of nesfatin-1 may be a sensitive marker of epileptic seizures. However, the details of nesfatin-1 physiology ought to be clarified, and it may be considered suitable in the future, as a potential drug in the pharmacotherapy of obesity, especially in patients treated with antipsychotics and antidepressants. On the other hand, some putative nesfatin-1 antagonists may improve eating disorders.

Hypothalamic Subependymal Niche: A Novel Site of the Adult Neurogenesis

The discovery of undifferentiated, actively proliferating neural stem cells (NSCs) in the mature brain opened a brand new chapter in the contemporary neuroscience. Adult neurogenesis appears to occur in specific brain regions (including hypothalamus) throughout vertebrates’ life, being considered an important player in the processes of memory, learning, and neural plasticity. In the adult mammalian brain, NSCs are located mainly in the subgranular zone (SGZ) of the hippocampal dentate gyrus and in the subventricular zone (SVZ) of the lateral ventricle ependymal wall. Besides these classical regions, hypothalamic neurogenesis occurring mainly along and beneath the third ventricle wall seems to be especially well documented. Neurogenic zones in SGZ, SVZ, and in the hypothalamus share some particular common features like similar cellular cytoarchitecture, vascularization pattern, and extracellular matrix properties. Hypothalamic neurogenic niche is formed mainly by four special types of radial glia-like tanycytes. They are characterized by distinct expression of some neural progenitor and stem cell markers. Moreover, there are numerous suggestions that newborn hypothalamic neurons have a significant ability to integrate into the local neural pathways and to play important physiological roles, especially in the energy balance regulation. Newly formed neurons in the hypothalamus can synthesize and release food intake regulating neuropeptides and they are sensitive to the leptin. On the other hand, high-fat diet positively influences hypothalamic neurogenesis in rodents. The nature of this intriguing new site of adult neurogenesis is still so far poorly studied and requires further investigations.

AMP‐activated protein kinase is involved in induction of protective autophagy in astrocytes exposed to oxygen‐glucose deprivation

AMP‐activated kinase (AMPK) acts as the intracellular ATP depletion sensor, which detects and limits increases in the AMP/ATP ratio. AMPK may be significantly activated under stress conditions that deplete cellular ATP levels such as ischemia/hypoxia or glucose deprivation. Recent studies strongly suggest that AMPK participates in autophagy regulation, but it is not known whether AMPK activated by ischemia regulates autophagy in astrocytes and the consequence of autophagy activation in ischemic astrocytes are unclear. We have investigated the contribution of AMPK to autophagy activation in rat primary astrocyte cultures subjected to ischemia‐simulating conditions (combined oxygen glucose deprivation, OGD) and its potential effects on astrocyte damage induced by OGD (1–12 h). The evidence supports the conclusion that AMPK activation at early stages of OGD is involved in induction of protective autophagy in astrocytes. Inhibition of AMPK, either by siAMPKα1 or by compound C, significantly attenuated the expression of autophagy‐related proteins and decrease of astrocyte viability following OGD. The findings provide additional data about the role of AMPK in ischemic astrocytes and downstream responses that may be involved in OGD‐induced protective autophagy.

The novel neuropeptide phoenixin is highly co-expressed with nesfatin-1 in the rat hypothalamus, an immunohistochemical study

The hypothalamus regulates a number of autonomic functions essential for homeostasis; therefore, investigations concerning hypothalamic neuropeptides and their functions and distribution are of great importance in contemporary neuroscience. Recently, novel regulatory factors expressed in the hypothalamus have been discovered, of which nesfatin-1 and phoenixin (PNX), show intriguing similarities in their brain distributions. There are currently few studies characterizing PNX expression, so it is imperative to accurately trace its localization, with particular attention to the hypothalamic nuclei and nesfatin-1 co-expression. Using fluorescence and classical immunohistochemical stainings on adult rat brain, we visualized the potential co-expression of nesfatin-1 and PNX immunoreactive cells. We have demonstrated a distinct PNX-immunoreactivity in 21-32% of cells in the arcuate nucleus, paraventricular nucleus, ventromedial and lateral hypothalamus. Nesfatin-1 expression reached 45-68% of all neurons in the same sites, while co-expression was strikingly seen in the vast majority (70-86%) of PNX-immunoreactive neurons in the rat hypothalamic nuclei. Our results demonstrate for the first time, a wide distribution of PNX in the hypothalamus which could implicate a potential functional relationship with nesfatin-1, possibly in the regulation of the hypothalamic-pituitary-gonadal axis or other autonomic functions, which require further study.

Eotaxin, but not IL-8, is increased in upper and lower airways of allergic rhinitis subjects after nasal allergen challenge.

The aim of this study was to assess the impact of a single nasal allergen challenge (NAC) on levels of eotaxin and IL-8 and the inflammatory cells in upper and lower airways of allergic rhinitis (AR) patients. Twenty-four AR patients and 12 control subjects entered a sequential nasal placebo challenge and NAC study, out of the pollen season. Nasal lavage fluid (NLF) was obtained at baseline, 15 minutes, and 1, 5, and 24 hours postchallenge. Before and 24 hours after placebo/allergen challenge induced sputum was performed. NLF and induced sputum were evaluated for total cell count (TCC) and differential cell count and analyzed for concentrations of eotaxin and IL-8 using ELISA method. NAC in AR subjects was associated with significantly increased sputum (p = 0.008) and NLF (p < 0.001) eotaxin levels. Post-NAC IL-8 levels were significantly increased in NLF (p < 00001) but not in sputum (p = 0.080) of AR subjects. Increased eotaxin levels in NLF positively correlated with the increased TCC and eosinophils. Positive correlations were also found between NLF increased eotaxin level and sputum TCC, eosinophils, and macrophages. NAC is associated with the increased levels of eotaxin in lower airways of AR subjects. Allergen-induced secretion of eotaxin in nasal mucosa of AR subjects is involved in determining the cellular character of both upper and lower airway inflammation.

Effects of long-term treatment with the neuroleptics haloperidol, clozapine and olanzapine on immunoexpression of NMDA receptor subunits NR1, NR2A and NR2B in the rat hippocampus.

BACKGROUND Antagonists of the N-methyl-d-aspartate receptor (NMDA-R) are associated with symptoms of schizophrenia, leading to the hypothesis that NMDA-R hypofunction leads to the pathogenesis of disease. We evaluated the long-term effect of neuroleptic administration on the NMDA subunits via immunohistochemical analysis. METHODS Rats received olanzapine, clozapine and haloperidol before evaluation of the expression of the NR1, NR2A and NR2B subunit proteins in the hippocampal areas of the brain, via a densytometric analysis of immunoexpression in the rat hippocampus. RESULTS All of the neuroleptics examined caused a decrease in the expression of the NR1 subunit, and thus, one can assume that both olanzapine, clozapine and haloperidol decreased the number of NMDA receptors in the CA1 and CA2 areas of the brain. CONCLUSIONS A decrease in hippocampal glutamatergic signalling after long-term neuroleptic administration may cautiously explain the incomplete effectiveness of these drugs in the therapy of schizophrenia-related cognitive disturbances.

Decreased percentage of CD4+Foxp3+TGF-β+ and increased percentage of CD4+IL-17+ cells in bronchoalveolar lavage of asthmatics

BackgroundAsthma is a chronic inflammatory disorder of the airways with the proven role of Th2 cells in its pathogenesis. The role and characteristic of different subsets of CD4+ cells is much less known.AimThe aim of the study was to analyze the incidence of different subsets of CD4+ T cells, in particular different subsets of CD4+ cells with the co-expression of different cytokines.MethodsTwenty five stable asthmatic and twelve age-matched control subjects were recruited to the study. Bronchoscopy and bronchoalveolar lavage (BAL) were performed in all study subjects. CD4+ T cells were isolated from BAL fluid by positive magnetic selection. After stimulation simultaneous expression of TGF-β, FoxP3, CD25, IFN-γ, IL-4, TNF-α (set 1); IL-10, FoxP3, CD25, IFN-γ, IL-4, MIP-1β (set 2); IL-17A, IL-8, IFN-γ, IL-4, MIP-1β (set 3) were measured by flow cytometry.ResultsThe percentage of CD4+ cells co-expressing Foxp3 and TGF-β (CD4+Foxp3+TGF-β+ cells) was significantly lower (P = 0.03), whereas the percentage of CD4+IL-17+ cells (P = 0.008), CD4+IL-17+ IFN-γ+ cells (P = 0.047) and CD4+IL-4+ cells (P = 0.01) were significantly increased in asthmatics compared with that seen in healthy subjects. A significantly higher percentage of CD4+Foxp3+ cells from asthma patients expressed IFN-γ (P = 0.01), IL-4 (P = 0.004) and CD25 (P = 0.04), whereas the percentage of CD4+IL-10+ cells expressing Foxp3 was significantly decreased in asthmatics (P = 0.03). FEV1% predicted correlated negatively with the percentage of CD4+IL-17+ cells (r = -0.33; P = 0.046) and positively with CD4+Foxp3+TGF-β+ cells (r = 0.43; P = 0.01).ConclusionsOur results suggest that in the airways of chronic asthma patients there is an imbalance between increased numbers of CD4+IL-17+ cells and Th2 cells and decreased number of CD4+Foxp3+TGF-β+.

Escitalopram affects spexin expression in the rat hypothalamus, hippocampus and striatum

BACKGROUND Spexin (SPX) is a recently discovered neuropeptide that exhibits a large spectrum of central and peripheral regulatory activity, especially when considered as a potent anorexigenic factor. It has already been proven that antidepressants, including selective serotonin reuptake inhibitors (SSRI), can modulate peptidergic signaling in various brain structures. Despite these findings, there is so far no information regarding the influence of treatment with the SSRI antidepressant escitalopram on brain SPX expression. METHODS In this current study we measured SPX mRNA and protein expression in the selected brain structures (hypothalamus, hippocampus and striatum) of rats chronically treated with a 10mg/kg dose of escitalopram using quantitative Real-Time PCR and immunohistochemistry. RESULTS Strikingly, long-term (4 week) drug treatment led to the downregulation of SPX expression in the rat hypothalamus. This supports the hypothesis that SPX may be involved in the hypothalamic serotonin-dependent actions of SSRI antidepressants and possibly also in the central mechanism of body mass increase. Conversely, SPX expression increased in the hippocampus and striatum. CONCLUSIONS This is the first report of the effects of a neuropsychiatric medication on SPX expression in animal brain. Our findings shed a new light on the pharmacology of antidepressants and may contribute to a better understanding of the alternative mechanisms responsible for antidepressant action.

Effects of neuroleptics administration on adult neurogenesis in the rat hypothalamus

BACKGROUND Among many factors influencing adult neurogenesis, pharmacological modulation has been broadly studied. It is proven that neuroleptics positively affect new neuron formation in canonical neurogenic sites - subgranular zone of the hippocampal dentate gyrus and subventricular zone of the lateral ventricles. Latest findings suggest that adult neurogenesis also occurs in several additional regions like the hypothalamus, amygdala, neocortex and striatum. As the hypothalamus is considered an important target of neuroleptics, a hypothesis can be made that these substances are able to modulate local neural proliferation. METHODS Experiments were performed on adult male rats injected for 28 days or 1 day by three neuroleptics: olanzapine, chlorpromazine and haloperidol. Immunohistochemistry was used to determine expression of proliferation marker (Ki-67) and the marker of neuroblasts - doublecortin (DCX) - which may inform about drug influence on adult neurogenesis at the level of the hypothalamus. RESULTS It was shown that a single injection of antipsychotics causes significant decrease in hypothalamic DCX expression, but after chronic treatment with chlorpromazine, but not olanzapine, there is an increase in the number of newly formed neuroblasts. Haloperidol has the opposite effect - its long-term administration decreases the number of DCX-positive cells. Cell proliferation levels (Ki-67 expression) increase after long-term drug administration, whereas their single doses do not have any modulatory effect on proliferation potential. CONCLUSIONS Our results throw a new light on the neuroleptics mechanism of action. They also support the potential role of antipsychotics as a factor that can modulate hypothalamic neurogenesis with putative clinical applications.

Morphological and enzymatic changes caused by a long-term treatment of female rats with a low dose of gonadoliberin agonist and antagonist

Summary Background Long-term treatment with gonadoliberin analogs is used to block the hypothalamic-pituitary-gonadal axis. The use of these agents is generally considered to be safe; however, some observations suggest the possibility of adverse effects. Material/Methods We investigated whether a 3-months administration of a low dose (6 μg/kg b.w.) of dalarelin – a new agonist, and cetrorelix – a known antagonist of GnRH to female rats causes morphological changes in pituitary gland, ovaries, uterus and liver (HE and VG staining); effects on pituitary, hepatic and blood enzyme activities (histochemical and kinetic methods, respectively), and on the blood lipid profile (colorimetric methods); and to what extent these changes are reversible. Results Applying analogs effectively inhibited ovulation, affected the uterine endometrium and changed histological appearance of the liver (e.g., steatosis). They altered activities of marker enzymes of cellular respiration, gluconeogenesis and intracellular digestion in the liver and, partially in the pituitary gland, caused undesirable changes in the activities of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and creatine kinase, and a concentration of cholesterol HDL fraction and triglycerides in the blood. Both morphological and enzymatic effects were more evident after antagonist administration; changes in the blood lipid profile were more evident after agonist administration. In both analogs histological and enzymatic changes persisted a relatively long time after the discontinuation of the treatment. Conclusions The low dose of dalarelin and cetrorelix is sufficient to cause limited damage of hepatic cells and may modify the function of pituitary, ovaries, uterus and liver as well as other organs, even after discontinuation of the treatment.