Pharmacological protection of vascular endothelium in acute COVID-19

Since the beginning of the COVID-19 pandemic, there has been an urgent need to find effective treatment. It is widely known that virus attacks and damages mostly the lungs, but also infect vascular endothelial cells. Therefore, the protection of the endothelium is a promising target in the therapy of COVID-19 and its complications. In this review article, we focused on several groups of drugs with potential to protect the endothelium. The most promising ones are angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, drugs targeting angiotensin-converting enzyme 2, heparins, sulodexide, acetylsalicylic acid, statins, tocilizumab, baricitinib, and defibrotide. Although the short period of trials and the lack of data necessitate further research, endothelial protection remains a promising target for COVID-19 therapy.

Highly organized nanostructures for brain drug delivery--new hope or just a fad?

The blood-brain barrier significantly impedes treatment of central nervous system disorders by preventing drug entry into the brain. Several strategies have been developed to overcome this problem, but progress has been hampered due to a lack of efficacious drug delivery systems (DDS). Now, owing to DDS, therapeutic compounds can be transported to the site of action and accumulate there. This modern approach allows one to decrease the required dose of drug and, therefore, minimize toxicity and side effects. Also, treatment efficiency is increased. Highly organized nanostructures made of biological, polymeric or carbon-based materials are promising carriers in drug delivery to the brain, due to their unique and easily tailorable properties. The drug can be either attached to or entrapped in a carrier. To achieve greater site specificity and selectivity, DDS can be also modified with suitable ligands, providing identification of the molecular site of action. This review illustrates recent advances in using highly-organized structures: dendrimers, fullerenes, liposomes, micelles, nanogels, nanoparticles and nanotubes for this purpose. We also discuss advantages and limitations of each system.

Culture morphology of the autologous cultivated corneal epithelium

PURPOSE

Ocular surgery based on cultivated corneal epithelium has become a very promising procedure eligible to restore the ocular surface. Analysis of morphologic features and the phenotype of cultivated epithelial cells determines their quality and eligibility of transplantation.

MATERIAL AND METHODS

Corneal epithelial cultures were carried out in 25 patients suffering from limbal deficiency after chemical or thermal burns. Fellow healthy eyes were the source of limbal epithelium for the culture. Limbal cells from a 2 mm2 biopsy were seeded on an amniotic membrane after enzymatic pretreatment. Cultures were carried in standard conditions in a supplemented DMEM HAM/F12 medium in the presence of 3T3 fibroblasts. Light microscopy was used to analyze the regularity of the cultivated epithelial layer, histologic examination was used to establish number of epithelial layers, and immunohistochemistry for epithelial and proliferation markers was applied to confirm cell origin and proliferative potential. Staining for cytokeratin 3, 12, 19, connexin 43, and protein p63 was performed.

RESULTS

In 25 donors, 27 cultures of the epithelium were performed. In 2 cases, plates were contaminated. Both cultures were repeated. In 84% of the cultures, regular stratified growth of the epithelium with complete covering of amniotic membrane was observed. In 16% of cultures, growth was not regular, showing differences in the number of cell layers. Staining for cytokeratin 3/12 confirmed the corneal origin of cultivated epithelia. The number of epithelial layers ranged from 3 to 9; the average was 5.3 +/- 1.9 layers.

CONCLUSION

Cultures of limbal epithelial cells are a valuable source of tissue for restoration of the corneal epithelium.

Metformin increases phagocytosis and acidifies lysosomal/endosomal compartments in AMPK-dependent manner in rat primary microglia

Recent evidence suggests that metformin shows beneficial effects in experimental models of neuroinflammatory diseases. The aim of the present study was to determine the effect of metformin on phagocytosis and acidification of lysosomal/endosomal compartments in rat primary microglia in the presence of lipopolysaccharide (LPS) and/or beta-peptides (25-35), (1-40), and (1-42). Metformin increased the phagocytosis of fluorescent microspheres in the presence or absence of all the beta-peptides. However, the drug had no effect on the phagocytosis in LPS-stimulated microglia regardless of the presence of all the beta-peptides. Metformin acidified the lysosomal/endosomal compartments in the presence or absence of the beta-peptide 1-40 in both resting and activated microglia. To elucidate the mechanism of metformin action, we used 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside as an activator of adenosine monophosphate-activated protein kinase (AMPK) and compound C as a confirmed pharmacological inhibitor of AMPK. We have shown that metformin increased AMPK activity in microglial cells and that all observed effects are AMPK-dependent because the pretreatment of microglia with compound C reversed the effects of the drug. Since degradation of proteins in lysosomal/endosomal compartments depends largely on their phagocytosis and acidification, metformin may be beneficial in proteinopathies affecting the brain.

Ambivalent effects of compound C (dorsomorphin) on inflammatory response in LPS-stimulated rat primary microglial cultures

It was proven that compound C displays beneficial effects in models of inflammatory-induced anemia, ischemic stroke, and fibrodysplasia ossificans progressiva. Compound C influence on microglia, playing a major role in neuroinflammation, has not been evaluated yet. The aim of the present study was to determine the effect of compound C on cytokine release, NO, and reactive oxygen species (ROS) production. The rat microglial cultures were obtained by shaking the primary mixed glial cultures. Cytokine and nitrite concentrations were assayed using ELISA kits. ROS were assayed with nitroblue tetrazolium chloride. AMPK activity was assayed using the SAMS peptide. The expression of arginase I, NF-kappaB p65, and hypoxia-inducible factor-1 alpha (HIF-1 alpha) was evaluated using Western blot. Compound C displayed ambivalent effect depending on microglia basal activity. It up-regulated the release of TNF alpha and NO production and increased the expression of arginase I in non-stimulated microglia. However, compound C down-regulated IL-1 beta, IL-6 and TNF alpha release, NO, ROS production, and AMPK activity, diminished NF-kappaB and HIF-1 alpha expression, as well as increased arginase I expression in lipopolysaccharide (LPS)-stimulated microglia. Compound C did not affect iNOS expression and IL-10 and TGF-beta release in non-stimulated and LPS-stimulated microglia. The observed alterations in the release or production of inflammatory mediators may be explained by the changes in NF-kappaB, HIF-1 alpha, and arginase I expression and 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolinum bromide values in response to LPS, whereas the basis for the compound C effect on non-stimulated microglia remains to be investigated.

AICAR (5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside) increases the production of toxic molecules and affects the profile of cytokines release in LPS-stimulated rat primary microglial cultures

AICAR (5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside, Acadesine, AICA riboside) is an activator of AMP-activated protein kinase (AMPK). The results of recent studies suggest that AICAR, in addition to its application for treating metabolic disorders, may also have therapeutic potential for treating neuroinflammatory diseases where reactive microglia play an etiological role. However, the molecular mechanisms of action by which AICAR exerts its anti-inflammatory effects still remain unclear or controversial. In this paper we attempt to evaluate the effects of AICAR on non-stimulated and LPS-activated rat primary microglial cell cultures. The presented evidence supports the conclusion that AMPK activated by AICAR is involved in regulation of ROS and cytokine production (IL-1 beta, TNF-alpha (6h), IL-10 and TGF-beta) as well as arginase I and PGC-1alpha expression. Furthermore, we found that the effects of AICAR on IL-6 and TNF-alpha (12, 24h) release and on the expression of iNOS and NF-kappaB p65 are not AMPK-dependent because the pre-treatment of LPS-activated microglia with compound C (a pharmacological inhibitor of AMPK) did not reverse the effect of AICAR. The results of the presented study provide additional data about AMPK-dependent and -independent mechanisms whereby AICAR may modulate inflammatory response of microglia.

Limbal stem cells transplantation in the reconstruction of the ocular surface: 6 years experience

PURPOSE

To analyze the graft survival rate and stability of the corneal surface in patients who underwent limbal stem cell transplantation. Three surgical techniques were performed based on the origin of the ocular surface lesion: conjunctival limbal autograft (CLAU), living-related conjunctival limbal autograft (lr-CLAL), and keratolimbal allograft (KLAL) transplantations.

METHODS

Nonrandomized consecutive comparative case series study. Eighty-four patients (90 eyes; 31 women and 53 men; age range: 11-78 years) were included in the study. Mean follow-up was 31.2 months (range: 6-72 months). Patients were divided into three groups: CLAU, lr-CLAL, and KLAL, comprising 21, 26, and 43 eyes, respectively. Graft survival rate and clinical success of the stem cell transplantation was confirmed by impression cytology. The Kaplan Meier survival curve and generalized Peto tests were used for the analyses.

RESULTS

Graft survival rate and the regularity of the corneal surface differed significantly between the allo- and autografts. The 3-year and 6-year graft survival rates were 76.1% and 61.9%, respectively, for the autologous transplantation group, and 59.4% and 46.3%, respectively, for the allogeneic transplantation group. Corneal surface restoration correlated with positive staining for corneal epithelial cells in impression cytology.

CONCLUSIONS

Significantly better long-term outcomes were achieved with autotransplantation of the limbus compared with allogeneic limbal grafts from living-related and cadaveric donors.

Activation of cPLA2 and sPLA2 in astrocytes exposed to simulated ischemia in vitro

Both cytosolic PLA(2) (cPLA(2)) and secretory PLA(2) (sPLA(2)) have been implicated in pathology of cerebral ischemia. However, which of PLA(2) isoforms in astrocytes is responsible for arachidonic acid (AA) release contributing to their ischemic injury remains to be determined. The aim of the present study was to investigate the time-dependent activation of cPLA(2) and sPLA(2) in astrocytes exposed to combined oxygen glucose deprivation (OGD) as well as to evaluate the effectiveness of their pharmacological blockage as a method of preventing ischemic damage of the glial cells. It was shown that exposure of cultured astrocytes to OGD (0.5-24h) causes an increase in cPLA(2) and sPLA(2) expression and activity. The role of AA liberated mainly by cPLA(2) in the process of apoptosis was also demonstrated. To confirm the specific role of cPLA(2) and sPLA(2) in the mechanism of cells injury by OGD exposure, the effect of AACOCF(3) as cPLA(2) inhibitor and 12-epi-scalaradial as sPLA(2) inhibitor on AA release was examined. It was proved that simultaneous pharmacological blockade of enzymatic activity of cPLA(2) and sPLA(2) during OGD by AACOCF(3) and 12-epi-scalaradial substantially improves survival of ischemic injured glial cells.

Calcineurin and Erk1/2-signaling pathways are involved in the antiapoptotic effect of cyclosporin A on astrocytes exposed to simulated ischemia in vitro

The present study focused on mechanisms involved in the anti-apoptotic effect of cyclosporin A (CsA) towards ischemic injured astrocytes in vitro [under combined oxygen glucose deprivation (OGD)]. We investigated whether this action might be mediated through activation of extracellular signal regulated kinases 1 and 2 (Erk1/2) or attenuation of calcineurin (CaN) by immunosuppressant in ischemic astrocytes. Additionally, the influence of CsA on phosphorylation of Akt kinase was determined. After 21 days of in vitro culture, astrocytes were subjected to OGD (for 8 h) and CsA (0.25-10 microM); 0.25 microM CsA distinctly stimulated the Erk1/2 pathway in astrocytes exposed to OGD. This protective effect of CsA was strongly associated with CaN inhibition, increased expression of anti-apoptotic factors such as Bcl-X(L) and NF-kappaB, as well as suppression of caspase-3 activity. Maximum p-Akt kinase expression was observed following treatment with 1 microM CsA. Finally, we also demonstrated that the beneficial effect of CsA at a concentration of 10 microM is related mainly to strong CaN inhibition. The results obtained suggest that, depending on the concentration used, CsA might act as a protective agent towards ischemia-injured astroglial cells through alternative intracellular pathways associated with increased p-Erk1/2 and p-Akt expression or CaN inactivation.

Inhibition of arachidonic acid release by cytosolic phospholipase A2 is involved in the antiapoptotic effect of FK506 and cyclosporin a on astrocytes exposed to simulated ischemia in vitro

In the present study, we investigated whether the protective effect of FK506 and cyclosporin A (CsA) against in vitro ischemic injury of astrocytes might be mediated through attenuation of cytosolic isoform of phospholipase A(2) (cPLA(2)) expression and activity as well as inhibition of arachidonic acid (AA) release. On the 21st day in vitro, cultures of rat astrocytes were subjected to ischemia-simulating conditions (combined oxygen glucose deprivation) for 8 h and exposed to FK506 (10 - 1,000 nM) and CsA (0.25 - 10 microM). Obtained data suggest the cross-talk between the action of 0.25 - 10 microM CsA as well as 1 microM FK506 on calcineurin (CaN) and cPLA(2) in anti-apoptotic signal transduction pathways. Moreover, we have shown that immunosuppressants at these concentrations protected glial cells against ischemia-induced apoptosis through the increase of cell viability, mitochondrial function restoration, and attenuation of oxidative stress. Finally, in our study, low concentrations of FK506 (10 and 100 nM) exerted limited effects on the assessed parameters. Our findings document a key role either for CaN or cPLA(2) expression attenuation and AA release inhibition in the antiapoptotic effect of FK506 and CsA in ischemic astrocytes.

Ebselen attenuates oxidative stress in ischemic astrocytes depleted of glutathione. Comparison with glutathione precursors

In this study, we investigated the protective effect of ebselen, a seleno-organic compound with antioxidant activity, towards astrocyte degeneration caused by exposure to simulated in vitro ischemic conditions and simultaneous depletion of glutathione (GSH). Depletion of GSH was induced by 24 h pretreatment with L-buthionine-(S,R)-sulfoximine (BSO). In this experimental paradigm, we examined the effects of ebselen (1-40 microM) on apoptosis, mitochondrial function, reactive oxygen species (ROS) production, intracellular GSH level and mitochondrial transmembrane potential (MTP). In addition, we also compared the antioxidant potential of ebselen with cystine and methionine as precursors of GSH synthesis as well as with GSH ethyl ester. Our study demonstrated that toxicity of simulated ischemia conditions was enhanced when intracellular GSH was depleted. Treatment with ebselen, especially at concentrations of 20 and 40 microM prevented ischemia-induced cytotoxicity. Our study has shown that antiapoptotic effect of ebselen is associated with its strong antioxidant properties, preservation of MTP and possibly conservation of mitochondrial GSH during cytoplasmatic GSH depletion caused by oxidative damage. Also, promoting GSH synthesis by the delivery of its substrates, like cystine or inhibition of the efflux by methionine may be a powerful strategy to minimize cell damage in the nervous tissue after ischemia.

Effect of aniracetam on phosphatidylinositol transfer protein alpha in cytosolic and plasma membrane fractions of astrocytes subjected to simulated ischemia in vitro

Brain ischemia affects phosphoinositide metabolism and the level of lipid-derived second messengers. Phosphatidylinositol transfer proteins (PI-PTs) are responsible for the transport of phosphatidylinositol (PI) and other phospholipids through membranes. Isoform of PI-TPs (PI-TPalpha) is an essential component in ensuring substrate supply for phospholipase C (PLC). The current study was conducted to examine potential effect of aniracetam on PI-TPalpha expression and to characterize the PI-TPalpha isoform distribution between membrane and cytosol fractions of astrocytes exposed to simulated ischemia in vitro. After 8 h period of ischemia, the level of PI-TPalpha was significantly higher in cytosol (by about 28%) as well as in membrane fraction (by about 80%) in comparison with control. We have found that aniracetam treatment of astrocytes in normoxia significantly increased the level of PI-TPalpha in membrane fraction with a maximal effect at 0.1 microM concentration of aniracetam (by about 195% of control). In membrane fractions of ischemic cells, aniracetam increased PI-TPalpha expression in a concentration-dependent manner. In ischemic cells, aniracetam (10 microM) has elevated PI-TPalpha expression up to 155% and 428% in cytosolic and membrane fractions in comparison with ischemic untreated cells, respectively. The study has shown that aniracetam significantly activates PI-TPalpha in cell membrane fraction and this effect might be connected with previously described activation of MAP kinase cascade.

Immunosuppressive Immunophilin Ligands Attenuate Damage in Cultured Rat Astrocytes Depleted of Glutathione and Exposed to Simulated Ischemia In VitroComparison with N-Acetylcysteine

The aim of the present study was to test the hypothesis that exposure of astrocytes depleted of glutathione (GSH) to simulated ischemia conditions in vitro and treated with immunosuppressant immunophilin ligands (cyclosporin A (CsA) and FK506) can increase intracellular GSH levels and that such mechanism may be responsible, at least in part, for their protective effects. In addition, we also compared the antioxidant properties of these immunosuppressants with N-acetylcysteine (NAC), a precursor of GSH synthesis. GSH depletion was induced by 24 h pretreatment with L-buthionine sulfoximine (BSO). Cultures of rat astrocytes were exposed to CsA (1-50 microM) and FK506 (1-1000 nM) and NAC (100 or 200 microM). We examined the effects of these compounds on apoptosis, cell viability, reactive oxygen species production and GSH content. Our study demonstrated that toxicity of simulated ischemia conditions were enhanced when intracellular GSH was depleted, and immunosuppressants (especially 100 nM FK506 and 10 microM CsA) effectively prevented ischemia toxicity in GSH depleted astrocytes. In addition, we have shown that interfering with the generation of GSH and attenuation, the rise of oxidative stress level by NAC may be a powerful tool for prevention of ischemia-induced glial cell damage.

Erk1/2 and Akt kinases are involved in the protective effect of aniracetam in astrocytes subjected to simulated ischemia in vitro

The present study focused on the mechanism of cytoprotective effect of aniracetam on the primary rat astrocyte cultures exposed to simulated ischemia conditions in vitro. To study these mechanisms, the aniracetam-mediated modulation of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3-K)/Akt kinase pathways was determined. Simulated in vitro ischemia caused death of approximately 35% of astrocytes via apoptosis and decreased cell viability about 50% at 8 h. Exposure to aniracetam at concentrations of 0.1-10 microM in these conditions significantly decreased the number of apoptotic cells. Moreover, the intensification of 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolinum bromide (MTT) conversion and the decrease of lactate dehydrogenase (LDH) release after 1 and 10 microM aniracetam treatment were observed indicating a significant increase in cell viability. When cultured astrocytes were incubated during 8 h simulated ischemia with [1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene] (U0126), an extracellular regulated kinase 1 and 2 (Erk1/2) inhibitor or wortmannin, a phosphatidylinositol 3-kinase (PI3 kinase)/Akt inhibitor, the cell apoptosis was accelerated. These effects of used kinase inhibitors (both U0126 and wortmannin) were antagonized by adding 1 and 10 microM aniracetam to the culture medium. In addition, aniracetam significantly stimulated of phospho-Erk1/2 kinase and phospho-Akt expression. Maximum levels of Erk1/2 and Akt activation were observed as a result of treatment with 10 microM aniracetam. U0126 and wortmannin markedly attenuated the effects of aniracetam on expression of activated kinases. Results of the present study indicate that both Erk1/2 and PI 3-K/Akt kinase pathways are vital for cytoprotective effect of aniracetam.

Chlorpromazine and loxapine reduce interleukin-1beta and interleukin-2 release by rat mixed glial and microglial cell cultures

The cytokines IL-1beta and IL-2 are released from activated glial cells in the central nervous system and they are able to enhance catecholaminergic neurotransmission. There is no data concerning influence of antipsychotics on glial cell activity. Antipsychotics reaching the brain act not only on neurons but probably also on glial cells. The aim of this study was to evaluate the effect of chlorpromazine and loxapine on release of IL-1beta and IL-2 by mixed glial and microglial cell cultures. Chlorpromazine in concentrations 2 and 20 muM, and loxapine 0.2, 2 and 20 microM reduced IL-1beta secretion by LPS-activated mixed glia cultures after 1 and 3 days of exposure. Chlorpromazine in concentrations of 0.2, 2 and 20 microM reduced the IL-2 secretion in mixed glial cultures after 3 days of exposure. Loxapine in concentrations of 0.2, 2 and 20 microM reduced IL-2 secretion in mixed glia cultures after 1 and 3 days of exposure, and additionally loxapine decreased IL-1beta and IL-2 secretion in LPS-induced microglia cultures in concentrations of 2, 10 and 20 muM. Quinpirole-a D2 dopaminergic agonist increased LPS-induced IL-1beta and IL-2 secretion in mixed glia cultures only in the highest dose of 20 microM. These findings suggest the absence of functional dopamine receptors on cortical microglial cells. Mixed glia cultures deprived of microglia (by shaking and incubating with L-leucine methyl ester) did not release IL-1beta and IL-2. This observation suggests that microglia can be a source of assessed cytokines. Results of the present study support the view that antipsychotics act not only on neurons but also on glial cells. However, the clinical significance of these observations still remains unclear.

Immunophilin ligands decrease release of pro-inflammatory cytokines (IL-1beta, TNF-alpha and IL-2 in rat astrocyte cultures exposed to simulated ischemia in vitro

The aim of present study was to evaluate the effects of immunophilin ligands (cyclosporin A, FK506 and rapamycin) on the simulated ischemia-induced release of pro-inflammatory cytokines (IL-1beta, TNF-alpha and IL-2) in rat primary astrocyte cell cultures. Astrocytes were exposed to cyclosporin A (CsA) (0.25, 0.5, 1, 10, 20 and 50 microM), FK506 (1, 10, 100, 1000 nM) and rapamycin (10, 100, 500 and 1000 nM). In vitro simulated ischemia significantly increased secretion of IL-1beta, TNF-alpha and IL-2 by astrocyte cultures deprived of microglia (by shaking and incubating with L-leucine methyl ester). CsA (at concentrations of 10-50 microM), FK506 (at all used concentrations) and rapamycin (in dose-dependent manner) significantly attenuated IL-1beta release after 24 h exposure to ischemic conditions. Immunophilin ligands at all used concentrations significantly decreased TNF-alpha levels in culture media after 24 h exposure to ischemia. Moreover, significant decrease in IL-2 secretion at 0.25, 0.5, 1 and 50 microM CsA and FK506 at concentrations of 100 and 1000 nM were observed. The results suggest that immunophilin ligands may regulate glial activity during ischemia by affecting the release of pro-inflammatory cytokines.

[Culture of the corneal epithelium--comparison of the mitotic potential of limbal cells from living and cadaveric donors]

PURPOSE

We analyse effectiveness of corneal limbal cells' culture prepared from heart-beating organ donors, that include living donors and from cadaver donors buttons following 3 days storage in 4 degrees C in Likorol.

MATERIAL AND METHODS

For experiment 12 adults (living and heart-beating organ donors) aged 28-63 (mean 46.3) and 12 corneal buttons of cadaver (aged 18-51, mean 34.1) were qualified. Tissue samples (1 mm2) were taken from superior corneal limbus. Sample from living donor obtained during routine operation was sent immediately to laboratory, as well as from heart-beating organ donor. The limbal biopsy of preserved cornea was taken after 3 days storage in 4 degrees C (Likorol). Samples were treated with trypsin/EDTA solution before culture. Collected cells in similar density in 1 ml of medium laid on dishes inserts, covered with fibrin (Tissucol) and cultured in presence of feeder layer of fibroblasts (L929 line). Epithelial cells were cultured for 14 days at 37 degrees C in humidified 5% CO2 atmosphere in supplemented 2:1 mixture of DMEM and Ham's F12. On the 14th day cells were collected. Number of cells per 1 ml of medium was counted by cytometer. Immunostaining for epithelium type (Keratin 3) was performed.

RESULTS

The number of cells obtained from cadaver donors reached 184.2+/-14.9% whereas from living donors revealed 1013.1+/-104.2%, increase in relation to number of delivered cells. We observed only 0.83+/-0.3 colonies per microscopic area in cultures from preserved tissue versus 6.67+/-0.6 colonies in cultures from living donor.

CONCLUSIONS

The preservation in 4 degrees C in Likorol significantly decreases proliferative potential of the corneal limbus.

Effect of antidepressants on the phospholipase A2 activity in plasma membranes of the rat brain cortex

The aim of the present study was to establish whether antidepressants (ADs) of potentially different chemical structure and mechanisms of action affected the phospholipase A2 (PLA2) activity in plasma membranes of the rat brain cortex. It was decided to evaluate the influence of imipramine (IMI), amitriptyline (AMI), fluvoxamine (FLU), mianserin (MIA) and tianeptine (TIA) on PLA2 activity after an acute and long-term (4 weeks) drug administration. To study the time-related effects of FLU on PLA2 activity, animals were treated for 1, 7, 14 and 28 days. The experiments were performed on male Wistar rats. The PLA2 activity was determined by the method of Strosznajder and Strosznajder as well as Jelsema with slight modifications. It was shown that ADs significantly changed the PLA2 activity in plasma membranes of the rat brain cortex and the effects depended on the dose, time of administration and the structure of the drug. Tricyclic ADs, both classic (IMI and AMI) as well as atypical (e.g. TIA) inhibited PLA2 activity. It seems that FLU was the only antidepressant, which induced either inhibition or activation of PLA2 depending on time of administration. It may be suggested that PLA2 appears to be a common target for drugs showing quite different mechanisms of action.

Methionine-enkephalin and leucine-enkephalin increase interleukin-1 beta release in mixed glia cultures

Interleukin-1 beta (IL-1 beta) is synthesized in the brain in response to LPS. Excessive IL-1 beta expression is observed in neurodegenerative diseases. The aim of this study was to evaluate the effects of methionine-enkephalin (ME) and leucine-enkephalin (LE) on the baseline and LPS-activated release of IL-1 beta in rat mixed glia cultures. ME and LE increased LPS-induced IL-1 beta release, which was not blocked by naloxone. Both ME and LE increased the baseline release of IL-1 beta, which was completely blocked by naloxone pretreatment. Mixed glia cultures deprived of microglia (by shaking and incubating with L-leucine methyl ester) did not release IL-1 beta, which indicates microglia as a source of the changes in IL-1 beta release. The results of the study suggest that neurons may regulate glial activity through releasing enkephalins.

Aniracetam attenuates apoptosis of astrocytes subjected to simulated ischemia in vitro

The aim of the present study was to establish whether aniracetam is capable of protecting cultured rat astrocytes against ischemic injury. Treatment of the cultures with aniracetam (1, 10 and 100 mM) during 24 h ischemia simulated in vitro significantly decreased the number of apoptotic cells. The antiapoptotic effects of the drug were confirmed by the increase of intracellular ATP and phosphocreatine (PCr) levels and the inhibition of the caspase-3 activity. Aniracetam also attenuated cellular oxidative stress by decreased production of reactive oxygen species (ROS). These effects were associated with the decrease in levels of c-fos and c-jun mRNA in primary astrocyte cultures exposed to 24 h ischemia. When cultured astrocytes were incubated during 24 h simulated ischemia with wortmannin, a phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor or PD98059, a mitogen-activated protein (MAP)/extracellular signal regulated kinase (ERK) (MEK) inhibitor the cell apoptosis was accelerated. This effect was antagonized by adding 100 mM aniracetam to the culture medium. These findings suggest that the protective effect of aniracetam is mediated by PI 3-kinase and MEK pathways in the downstream mechanisms.

Piracetam and vinpocetine exert cytoprotective activity and prevent apoptosis of astrocytes in vitro in hypoxia and reoxygenation

The aim of the present study was to establish whether piracetam (2-pyrrolidon-N-acetamide; PIR) and vinpocetine (a vasoactive vinca alkaloid; VINP) are capable of protecting astrocytes against hypoxic injury. Using the model of astrocyte cell culture we observed the cells treated with PIR and VINP during and after in vitro simulated hypoxia. Cell viability was determined by Live/Dead Viability/Cytotoxicity Assay Kit, LDH release assay and MTT conversion test. Apoptotic cell death was distinguished by a method of Hoechst 33342 staining underfluorescence microscope and caspase-3 colorimetric assay. In addition the intracellular levels of ATP and phosphocreatine (PCr) were evaluated by bioluminescence method. Moreover, the effect of the drugs on the DNA synthesis was evaluated by measuring the incorporation of [3H]thymidine into DNA of astrocytes. PIR (0.01 and 1 mM) and VINP (0.1 and 10 microM) were added to the medium both during 24 h normoxia, 24 h hypoxia or 24 h reoxygenation. Administration of 1 mM PIR or 0.1 microM VINP to the cultures during hypoxia significantly decreases the number of dead and apoptotic cells. The antiapoptic effects of drugs in the above mentioned concentrations was also confirmed by their stimulation of mitochondrial function, the increase of intracellular ATP, and the inhibition of the caspase-3 activity. The prevention of apoptosis was accompanied by the increase in ATP and PCr levels and increase in the proliferation of astrocytes exposed to reoxygenation. The higher concentration of VINP (10 microM) was detrimental in hypoxic conditions. Our experiment proved the significant cytoprotective effect of 1 mM PIR and 0.1 microM VINP on astrocytes in vitro.

Does trimetazidine exert cytoprotective activity on astrocytes subjected to hypoxia in vitro?

The aim of the present study was to establish whether trimetazidine (TMZ) is capable of protecting astrocytes against hypoxic injury. Using the model of astrocyte cell culture we tried to observe the cells treated with TMZ before, during and after hypoxia simulated in vitro. Cell viability was determined by Live/Dead (viability/cytotoxicity) Assay Kit and MTT conversion test. Apoptotic cell death was distinguished by a method using fluorescence microscopy with Hoechst 33342. The effect of the drug on the DNA synthesis was evaluated by measuring the incorporation of [3H]thymidine into DNA of astrocytes. TMZ stimulates the proliferation of astrocytes most significant one when the astrocytes are exposed to the drug in normoxia, hypoxia and/or re-oxygenation. Adding TMZ into cultures during re-oxygenation and hypoxial re-oxygenation significantly decreases the number of dead and apoptotic cells. Our experiment has proved that TMZ exerts the most significantly cytoprotective effect on astrocytes in vitro when added during hypoxia and/or re-oxygenation. We may conclude that the protective effect of TMZ depends on the sequence of drug adding and hypoxia/ re-oxygenation onset.

Role of astrocytes in pathogenesis of ischemic brain injury

Astrocytes play an important role in the homeostasis of the CNS both in normal conditions and after ischemic injury. The swelling of astrocytes is observed during and several seconds after brain ischemia. Then ischemia stimulates sequential morphological and biochemical changes in glia and induces its proliferation. Reactive astrocytes demonstrate stellate morphology, increased glial fibrillary acidic protein (GFAP) immunoreactivity, increased number of mitochondria as well as elevated enzymatic and non-enzymatic antioxidant activities. Astrocytes can re-uptake and metabolize glutamate and in this way they control its extracellular concentration. The ability of astrocytes to protect neurons against the toxic action of free radicals depends on their specific energy metabolism, high glutathione level, increased antioxidant enzyme activity (catalase, superoxide dismutase, glutathione peroxidase) and overexpression of antiapoptotic bcl-2 gene. Astrocytes produce cytokines (TNF-alpha, IL-1, IL-6) involved in the initiation and maintaining of immunological response in the CNS. In astrocytes, like in neurones, ischemia induces the expression of immediate early genes: c-fos, c-jun, fos B, jun B, jun D, Krox-24, NGFI-B and others. The protein products of these genes modulate the expression of different proteins, both destructive ones and those involved in the neuroprotective processes.

Effect of nebracetam on content of high-energy phosphates and morphometry of rat astrocytes in vitro. Comparison with piracetam

The present study was initiated to examine the effect of nebracetam, a nootropic drug, on various biochemical and morphometric parameters in order to gain some insight into the mechanism of this agent action. The content of adenosine triphosphate (ATP) and phosphocreatine (PCr) and 3H-valine incorporation into proteins was measured and the morphometry was performed after nebracetam and piracetam treatment of rat astrocytes cultured in vitro with or without dibutyryl 3',5'-cyclic adenosine monophosphate (dBcAMP). Nootropics were added into the culture medium for 2 weeks at the final concentration of 10(-7) M. Cultured astrocytes treated with either nebracetam or piracetam showed decreased intracellular ATP and PCr levels. The addition of nebracetam and dBcAMP to cultures caused an increase of PCr content in astrocytes. The astrocytes treated with nebracetam showed a decrease in 3H-valine incorporation. The increase of 3H-valine incorporation into astrocytes after piracetam with dBcAMP treatment was found. Nootropic drugs change morphometric parameters (cell area, perimeter and form factor) of cultured astrocytes. It can be concluded that nootropics have differentiated influence on both the energetic metabolism and morphology of rat astrocytes in vitro.

Influence of piracetam and oxiracetam on the content of high-energy phosphates and morphometry of astrocytes in vitro

The nootropic drugs, including piracetam (PIR) and oxiracetam (OXI) are used in the adjunctive treatment of dementia. They are thought to directly influence energetic processes in the brain and, therefore, they are supposed to improve memory and cognition. The content of adenosine triphosphate (ATP) and phosphocreatine (PCr) and 3H-valine incorporation into proteins were measured, and the morphometry was performed after PIR and OXI treatment of astrocytes cultured in vitro with or without dibutyryl 3',5'-cyclic adenosine monophosphate (dBcAMP). Nootropics were added into the culture medium for 2 weeks at a final concentration of 10(-7) M. It was shown that OXI increased ATP content in astrocytes cultured with or without dBcAMP. The increase in 3H-valine incorporation into astrocytes after PIR and OXI together with dBcAMP treatment was found. These results indicate that the presented research model allows to study energetic processes in cultured astrocytes. However, nootropic drugs changed morphometric parameters (cell area, perimeter and form factor) of cultured astrocytes as well. It can be concluded that PIR and OXI as nootropics have an opposing effect on the content of high-energy phosphates and shape of astrocytes in vitro.

Effect of antidepressants on ATP content, 3H-valine incorporation and cell morphometry of astrocytes cultured from rat brain

ATP is a potential marker of cell vialibility and growth. The content of ATP and 3H-valine incorporation into proteins were measured and the morphometry was performed after antidepressant treatment of astrocytes cultured in vitro with or without dibutyryl 3'5'-cyclic adenosine monophosphate (dB-cAMP). Antidepressants were added into the culture medium (for 24 h) at a final concentration of 10(-4)M (imipramine, amitriptyline, clomipramine, doxepine, mianserin) or 10(-5)M (maprotiline). It was shown that all antidepressants except maprotiline and imipramine increased ATP level and decreased 3H-valine incorporation into astrocytes. All drugs except clomipramine and maprotiline, diminished cell area and perimeter of astrocytes. The addition of dB-cAMP to cultures caused an increase of astrocyte form factor. It can be concluded that antidepressants have a significant effect on energy metabolism and differentiation of astrocytes cultured in vitro.

Nootropics: pharmacological properties and therapeutic use

This review summarizes the results of studies investigating the pharmacological properties, mechanisms of action, preclinical and clinical effects of nootropic drugs, and tries to integrate this knowledge in order to identify neuronal mechanisms underlying their therapeutic benefits and side effects.