Histamine stimulates nerve growth factor (NGF) secretion from cultured astrocytes. Histamine H(1)-receptor antagonists completely block its effect. In the present study, we determined the involvement ...of histamine-receptor subtypes in this process.
Radioligand-binding assay was used to establish the presence of histamine H(1)- and H(2)-receptors on new-born rat cortical astrocytes in primary culture. Histamine H(1)-, H(2)- and H(3)/H(4)-receptor ligands, and highly selective protein kinase C (PKC) inhibitor were used to influence NGF secretion from cultured astrocytes. NGF, released into the culture medium, was measured by NGF-ELISA.
Histamine H(1)-receptor agonists (histamine, selected histaprodifens) increased the secretion of NGF from cultured astrocytes in a concentration-dependent manner. H(1)-receptor antagonists/inverse agonists (mepyramine, triprolidine) and PKC inhibitor completely blocked the effect of histamine. Histamine H(2)- and H(3)-receptor agonists did not enhance NGF secretion significantly. In addition, H(2)- and H(3)/H(4)-receptor antagonists did not diminish histamine-stimulated NGF release.
Our results indicate that histamine H(1)-receptor and PKC are involved in the signal transduction pathway, responsible for histamine-stimulated NGF secretion from cultured astrocytes.
In exaggerated pain states, the activated astrocytes release several signalling molecules involved in cellular mechanisms of chronic pain. Among them, nerve growth factor (NGF) and interleukin ...(IL)-1β are both recognized as potent algogens. We previously showed that histamine is a potent stimulator of NGF production in rat cortical astrocytes in primary culture. Since histamine and IL-1β have common interactions in different physiological responses, in the present work we were interested to elucidate the molecular mechanisms involved in the interactions between histamine, IL-1β and NGF that could contribute to the processing of chronic pain. As an experimental model we used cultured rat cortical astrocytes. NGF and IL-1β levels in the culture medium were measured by ELISA. IL-1β mRNA expression was determined by RT PCR.
The results showed that the co-treatment of the cultured astrocytes with histamine and IL-1β significantly increased NGF secretion in comparison to the secretion observed with either histamine, or IL-1β alone. The histamine and IL-1β effect on NGF secretion was additive, dose-dependent and increased with increased concentrations of either histamine, or IL-1β. The additive effect of histamine and IL-1β on NGF secretion was strongly suppressed by histamine H1 receptor antagonist/inverse agonist mepyramine, protein kinase C (PKC) inhibitors (GF 109203X, Go 6976), and mitogen-activated protein kinase kinase (MAPK)-1 inhibitor (PD 98059); however, they did not influence significantly the NGF secretion evoked by IL-1β alone. Histamine also stimulated the secretion of IL-1β from cultured astrocytes and induced higher expression of IL-1β mRNA in comparison to untreated cells.
We concluded that histamine potently interacts with the synthesis and secretion of IL-1β and NGF in astroglial cells, and therefore can contribute to the development and maintenance of chronic pain, mediated by both algogens.
Histamine is a potent stimulator of nerve growth factor (NGF) production in both the central nervous system and in the periphery. The main signalling pathway, involved in the synthesis and secretion ...of NGF, includes activation of histamine H sub(1)-receptor, stimulation of Ca super(2+)-dependent protein kinase C (PKC) and mitogen-activated protein (MAP) kinase. Besides its direct stimulation of NGF production, histamine is able to stimulate it also indirectly. This effect of histamine results from its interactions with different cytokines, i.e. IL-1 beta and IL-6 which are also able to stimulate production of NGF.
This study compared the effects of toxicity of ethanol and its first metabolite acetaldehyde in rat astrocytes through cell viability and cell proliferation. The cells were treated with different ...concentrations of ethanol in the presence or absence of a catalase inhibitor 2-amino-1,2,4 triazole (AMT) or with different concentrations of acetaldehyde. Cell viability was assessed using the trypan blue test. Cell proliferation was assessed after 24 hours and after seven days of exposure to either ethanol or acetaldehyde.We showed that both ethanol and acetaldehyde decreased cell viability in a dose-dependent manner. In proliferation studies, after seven days of exposure to either ethanol or acetaldehyde, we observed a significant dose-dependent decrease in cell number. The protein content study showed biphasic dose-response curves, after 24 hours and seven days of exposure to either ethanol or acetaldehyde. Co-incubation in the presence of AMT significantly reduced the inhibitory effect of ethanol on cell proliferation.We concluded that long-term exposure of astrocytes to ethanol is more toxic than acute exposure. Acetaldehyde is a much more potent toxin than ethanol, and at least a part of ethanol toxicity is due to ethanol's first metabolite acetaldehyde.
V študiji smo primerjali toksi _nost etanola in njegovega prvega metabolita acetaldehida za podganje astrocite z dolo _itvijo celi _ne viabilnosti in proliferacije. Celi _ne kulture smo tretirali z razli _nimi koncentracijami etanola, etanola v prisotnosti inhibitorja katalaze 2-amino-1,2,4 triazol-a (AMT) ali z razli _nimi koncentracijami acetaldehida. Celi _no viabilnost smo vrednotili s pomo _jo testa s tripanskim modrilom, celi _no proliferacijo pa s štetjem celic in dolo _itvijo koncentracije proteinov po 24-urni, kot tudi 7-dnevni izpostavljenosti.S študijo smo pokazali, da tako etanol kot tudi acetaldehid v odvisnosti od njune koncentracije zmanjšata celi _no viabilnost. V študiji proliferacije sta etanol in acetaldehid, v odvisnosti od njunih koncentracij, zna _ilno zmanjšala število celic po 7-dnevni izpostavljenosti. Pri ugotavljanju vsebnosti proteinov smo dobili bifazno krivuljo tako po 24-urni, kot tudi po 7-dnevni izpostavljenosti razli _nim koncentracijam etanola oziroma acetaldehida. Prisotnost AMT je signifikantno zmanjšala u _inek etanola na celi _no proliferacijo.Zaklju _imo lahko, da je dolgotrajna izpostavljenost astrocitov etanolu bolj toksi _na kot akutna. Acetaldehid je mo _nejši toksin kot etanol in vsaj del toksi _nosti etanola je posledica delovanja njegovega prvega metabolita, acetaldehida.
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