Pharmacological and biochemical effects of Ginkgo biloba extract on learning, memory consolidation and motor activity in old rats.

Effect of administration of the standardized extract of Ginkgo biloba leaves (EGb 761) on learning, memory and exploratory behavior was estimated in water maze and hole-board tests. Rats (18-month old) received for three months EGb 761 at doses: 50, 100 and 150 mg/kg b.w. per day. After completion of the behavioral experiment, concentrations of neurotransmitters were estimated in selected brain regions. ANOVA demonstrated significant differences in the content of monoamines and metabolites between the treatment groups compared to the control. The increased level of 5-hydroxytryptamine (5-HT) in the hippocampus and 5-HIAA (5-HT metabolite) in the prefrontal cortex correlated positively with the retention of spatial memory. Positive correlation between platform crossings in SE during the probe trial and neurotransmitter turnover suggest improvement of spatial memory. Long-term administration of Ginkgo biloba extract can improve spatial memory and motivation with significant changes in the content and metabolism of monoamines in several brain regions.

Anti-myelin basic protein T cells protect hippocampal neurons against trimethyltin-induced damage.

We investigated the influence of administration of autoimmune T cells on trimethyltin-induced degeneration of hippocampal neurons. Female Lewis rats received 8 mg/kg trimethyltin intraperitoneally alone, or followed 24 h later by a second intravenous injection of anti-myelin basic protein T cells (green fluorescent protein-tagged). Neurodegeneration was assessed by NeuN and Nissl cell counts 21 days after trimethyltin injection. We found that neurodegeneration in the CA4 region of the hippocampus was significantly reduced in the group receiving T cells. T cells also caused an augmentation of trimethyltin-induced hippocampal astrocytic activation and astrocytic TrkA expression, which was particularly intense in the CA4 region. Our study provides the first evidence of neuroprotection evoked by transferred T cells following a neurotoxic brain insult. The data suggest that mediation of the neuroprotective effects of T-cell-released nerve growth factor occurs mainly via hippocampal astroglial TrkA receptors.

Influence of age and gender on cytokine expression in a murine model of Parkinson's disease.

OBJECTIVE: The neuroinflammatory reaction has been linked with Parkinson's disease. One of the hypotheses to explain the significance of age and gender (male predominance) effects on neurodegeneration in Parkinson's disease may result from a link between these risk factors and the inflammatory processes. Here, we investigated the expression of inflammatory mediators in relation to 1-methyl-4-phenyl-1,2,3,6-tetrahydropiridine (MPTP)-induced neurodegenerative processes in nigrostriatal pathway in young and aged male and female mice. METHODS AND RESULTS: We simultaneously assessed striatal tyrosine hydroxylase (TH) protein concentrations (Western blotting) and cytokine (TNFalpha, IFNgamma, IL-1beta, IL-6 and TGFbeta(1)) mRNA levels (RT-PCR) in young and aged (2- and 12-month-old) C57BL/6 male and female mice after 6 h, 1, 3, 7, 14, 21 days after MPTP intoxication. Western blotting analysis showed that at the early time points, males showed a greater reduction in striatal TH versus females. Additionally, in contrast to the aged mice, in young males and females the TH concentration gradually increased between the 7th and the 21st day after intoxication. The increases in TNFalpha, IL-1beta and IFNgamma after intoxication were faster in both young and aged males than females. In males (both ages), we observed an increase in TGFbeta(1) at the early time points. In contrast, in females (both ages) TGFbeta(1) was elevated at later time points. MPTP caused an increase in IL-6 in males and females, but this increase was significantly higher in females. CONCLUSIONS: A gender and age skewing of the cytokine gene expression in the striatum after intoxication may be related to the greater susceptibility in males as well as older animals to the detrimental effects of MPTP.

Dopamine, serotonin and noradrenaline changes in the striatum of C57BL mice following myelin oligodendrocyte glycoprotein (MOG) 35-55 and complete Freund adjuvant (CFA) administration.

Many data suggest involvement of inflammation in neurodegeneration. However, the exact mechanisms of this cooperation are poorly understood. We have previously shown that induction of inflammatory reaction, both before and after injury of the striatum, affects regeneration of dopaminergic neurons. In the present research we studied the role of inflammatory reaction in non-injured striatum. We used myelin oligodendrocyte glycoprotein (MOG) 35-55 in complete Freund's adjuvant (CFA) to elicit experimental autoimmune encephalomyelitis (EAE) mice model. As determined by HPLC, striatal dopamine (DA) and serotonin levels in mice treated with either MOG 35-55 in CFA or CFA alone were significantly higher compared to vehicle-treated controls on 13th day after induction. The ratio of homovanilic acid/dopamine (HVA/DA) and 3, 4 dihydroxyphenylacetic acid/dopamine (DOPAC/DA) were significantly lower in the MOG and CFA groups on 13th day, indicating decreased DA metabolism. Noradrenaline (NA) concentration did not differ between groups. Moreover, the striatal mRNA IL-1beta and TNF-alpha levels were elevated during induction phase of EAE in both groups, as determined by RT-PCR. Our data indicate regulatory connection between dopaminergic and immune systems.

Cyclooxygenases mRNA and protein expression in striata in the experimental mouse model of Parkinson's disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration to mouse.

Cyclooxygenases (COX) are associated with complex alteration in many pathologies of the central nervous system (CNS). Increased expression of COX-2 has been shown in injured or degenerated neurons, thus suggesting that COX-2 may contribute to neuronal damage. In this study, we present the expression of COX-1 and COX-2 mRNA and protein in striatum following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration to mice. MPTP causes an acute damage of dopaminergic neurons especially in the nigrostriatal dopaminergic system, thus diminishing dopamine (DA) content in striatum and decreasing the number of dopaminergic cells in the pars compacta of the substantia nigra (SN). C57Bl mice have received 60 mg/kg of MPTP introperitoneally. A group of mice received also rofecoxib 10 mg/kg from the 1st day following MPTP administration. Dopamine content in striatum (high-performance liquid chromatography-HPLC), mRNA expression of COX-1 and -2 (reverse transcriptase-polymerase chain reaction technique-RT-PCR), COX-1 and -2 protein content (immunoblotting) have been measured on day 1st, 3rd, 7th, 14th and 21st after the injury. We have found that COX-1 mRNA expression is not changed following MPTP administration, but COX-2 gene and protein expression in striatum increases from the 3rd to the 7th and 14th days, and diminishes on the 21st day. Production of prostaglandins is augmented only briefly after MPTP treatment and did not correlate with increased COX-2 mRNA and COX-2 protein production. Thus, the increase of COX-2 expression does not follow the acute stage of cell death but rather the recovery period after the injury. We also demonstrate that COX-2 activity inhibition by rofecoxib (10 mg/kg), which has been started 1 day after the injury, has not neuroprotective effect. Our study suggests that COX-2 does not contribute to neurons death following MPTP administration and that the inhibition of COX-2 activity is not beneficial to neurons injured by MPTP. However, COX-2 mRNA and protein expressions increase after MPTP injury; the role of these findings remains obscure.

Dexamethasone protects against dopaminergic neurons damage in a mouse model of Parkinson's disease.

The pathological process of neurodegeneration, which is observed in Alzheimer's (AD) and Parkinson's (PD) diseases and that follows any insult to the central nervous system, is accompanied by an inflammatory reaction, which is believed to contribute to the pathogenesis of the diseases. In accordance to this, the anti-inflammatory agents are suggested to be effective in slowing or inhibiting the degenerative process. In this study, we investigated the influence of dexamethasone (DXM) on the nigrostriatal dopaminergic neurons damage following administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropiridine (MPTP). Mice C57BL received pre-treatment of the various doses of dexamethasone followed by MPTP administration (40 mg/kg). We found that dexamethasone 1 mg/kg diminished a dopamine content depletion in striatum by about 20%, when the doses of 0.1 mg/kg was ineffective and 10 mg/kg even aggravate the dopamine content decrease. In the second step of the experiment, we chose the effective doses, 1 mg/kg, and started the treatment before and 24 h after MPTP administration. We observed the same protection in both situations: less dopamine depletion and less decrease in the number of dopaminergic cells in the substantia nigra (SN). Dexamethasone also similarly decreased the inflammatory reaction (glial activation, lymphocytic infiltration) in the injured areas. Our study showed that dexamethasone may exert a neuroprotective effect towards neurons injured by MPTP, but only when used in a proper dose. The mechanism of dexamethasone protective properties may be an inhibition of inflammatory process; however, direct interactions with neurons are also possible.

Post intoxicative therapeutic immunization with myelin oligodendrocyte glycoproteine (MOG 35-55) suppresses spontaneous regeneration of dopaminergic neurons injured with 1-methyl-4 phenyl-1,2,3,6-tetrahydropiridine (MPTP).

The pathological process of neurodegeneration is accompanied by an inflammatory reaction that is believed to contribute to the pathogenesis of neurodegenerative diseases. The aim of our study was to evaluate the influence of autoimmune reaction induced by post-traumatic vaccination with myelin self-antigen on spontaneous regeneration of dopaminergic neurons, injured with MPTP. C57BL mice were intoxicated with 40 mg/kg MPTP and seven days later immunized with MOG 35-55 peptide in CFA. On the 7th day following intoxication, the MPTP treated mice showed decrease of the dopamine level by 63% as compared to the control mice. However, starting from the 14th day following intoxication, a spectacular increase of dopamine content was observed. Immunization with MOG resulted in a statistically significant reduction of the increase in striatum as compared to non-immunized animals, and was lower by 23%, 17% and 15% on days 14, 28 and 50, respectively. Our results show suppressive influence of autoimmune reaction induced after injury on regeneration of dopamine cells intoxicated with MPTP.

Dynamics of expression of the mRNA for cytokines and inducible nitric synthase in a murine model of the Parkinson's disease.

The inflammatory reaction and oxidative stress has been linked with PD. Proinflammatory cytokines promote neurodegeneration or neuroprotection in different animal models. In addition, these cytokines have been reported to increase iNOS expression. With the RT-PCR method we evaluated mRNA levels for IL 1beta, IL6, TNF, IFNgamma, IL-10 and iNOS in the striatum of C57BL/6 mice after MPTP intoxication. The IL1beta mRNA expression rapidly increased and peaked at 6 h. The first increase of mRNA for TNFalpha and IFNgamma was noticed at 6-24 h and the second at the 7th day after MPTP intoxication. Two peaks of IL10 mRNA were seen, immediately (6 h) and at the 3 day post MPTP injection. The peak of mRNA level for IL6 was observed at the 7th day. Expression of mRNA for iNOS peaked at 24 h, started decreasing on the 3rd day, but was still present till the 14th day. Those findings suggest that cytokine network and iNOS may be involved in the development of immune changes accompanying degeneration of the nigrostriatal system.

Potential neuroprotective effect of ibuprofen, insights from the mice model of Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is one of the most common neurodegenerative diseases. An inflammatory reaction seems to be involved in the pathological process in PD. Prospective clinical studies with various nonsteroidal anti-inflammatory drugs (NSAIDs) have shown that ibuprofen decreases the risk of PD. In the present study we investigated the influence of ibuprofen on dopaminergic neuron injury in the mice model of PD. METHODS: Twelve-month-old male C57Bl mice were injected with MPTP together with various doses of ibuprofen (10, 30 or 50 mg/kg), administered 1 h before MPTP injection for 7 consecutive days. Evaluation concerned dopamine content in the striatum, tyrosine hydroxylase (TH) protein and α-synuclein expression measured 7 and 21 days post MPTP administration (dpa). RESULTS: MPTP caused injury to dopaminergic neuron endings in the striatum: dopamine content decreased by about 0% 7 dpa and by 85% 21 dpa; TH protein expression diminished by 21% 7 dpa; α-synuclein level decreased by 10 and 26% 7 and 21 dpa, respectively. Ibuprofen administration to mice treated with MPTP significantly increased the level of dopamine in the striatum 7 and 21 dpa. It also prevented TH protein decrease and increased α-synuclein level 21 dpa. CONCLUSIONS: Ibuprofen was shown to protect neurons against MPTP-induced injury in the striatum. The possible mechanism of the neuroprotective effect of ibuprofen might be associated with decreased dopamine turnover and cyclooxygenases inhibition resulting in lower reactive oxygen species formation.

Age- and sex-differences in the nitric oxide synthase expression and dopamine concentration in the murine model of Parkinson's disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

Parkinson's disease (PD) is an age- and sex-related neurodegenerative disorder of unknown aetiology. The involvement of nitric oxide synthase (NOS) in the etiopathogenesis of PD is quite well documented. We decided to examine changes in dopamine (DA) levels as well as iNOS, nNOS, eNOS mRNA and protein expression in the striatum of C57BL male and female (2- and 12-month old) mice in the course of PD-related neurodegeneration induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The significantly decreased level of DA was previously observed in male than in female, irrespective of age. In young mice the recovery of DA was significantly greater in female compared to male mice. On the contrary, both in male and female old animals the low concentration of DA was extended up to 21 days post MPTP injection. The increases in iNOS protein expression post MPTP intoxication occurred more rapidly in male (young and old) than in female mice. The pattern of changes in iNOS protein expression was also different in young versus aged mice. nNOS protein expression increased earlier in young male than young female mice. No changes were observed in eNOS expression. In conclusion, our results support the hypothesis of the involvement of iNOS and nNOS, but not eNOS in neurodegenerative processes. Our findings suggest that age- and sex-differences in DA concentration and iNOS expression as well as sex-differences of nNOS expression after intoxication may depend on the increased susceptibility of males as well as older animals to toxic effect of MPTP and aggravated process of recovery in old brains.

Influence of estrogens on neurodegenerative processes.

Gonadal steroids are known to be of prime importance in the normal maintenance of brain function. Data from epidemiological studies suggest that the decline in estrogen following menopause may increase the risk of neurodegenerative diseases. There is accumulating epidemiological evidence for neuroprotection by estrogens against neurodegenerative diseases, such as Alzheimer's disease. Although it is unclear whether estrogen may be effective in preventing further cognitive decline in women who already have Alzheimer's disease, several studies indicate that estrogen replacement improves the cognitive performance of postmenopausal women. Despite the somewhat controversial data from human studies, experimental investigations in different animals have shown that estrogen is neuroprotective. Although estrogens are known to exert several direct effects on neurons, the cellular mechanisms involved in the neuroprotective effects of estrogen are still unclear. Estrogen causes most of its neuroprotective effects by means of direct binding to specific nuclear receptors. The anti-oxidant effects of estrogens and activation of different membrane-associated intracellular signaling pathways or neurotrophic cross talk through the signal cascade shared with neurotrophic factors could also contribute to neuroprotection. In this article, we outline the evidence supporting a direct role of estrogen in neuronal survival, and

Long term administration of Hypericum perforatum improves spatial learning and memory in the water maze.

The aim of the present study is to investigate the effects of long-term Hypericum perforatum treatment on spatial learning and memory in rats. Hypericum preparation (HP) standardized to 0.3% hypericin content was administered orally for 9 weeks in doses of 4.3 and 13 microg/kg corresponding to therapeutic dosages in humans of 0.3 and 0.9 mg of total hypericins daily. A Morris water maze paradigm was used. The mean escape latency over 4 d for the Control group (21.9 s) and HP 4.3 group (21.7 s) was significantly greater than the latency of the HP 13 group (15.8s). In the probe trial on day 5, the HP 13 group crossed the correct annulus in the SE quadrant more often (4.5) than the other groups: Con (2.4) and HP 4.3 (3.1). After completion of the behavioral experiment, the regional brain concentrations of monoamines and metabolites were estimated in selected brain regions, i.e. prefrontal cortex, hippocampus and hypothalamus. Analysis of variance (ANOVA) demonstrated significant differences in the content of monoamines and metabolites between the treatment groups compared to the Control. The increased 5-hydroxytryptamine (5-HT) levels in the prefrontal cortex correlated positively with the retention of spatial memory. These findings show that the long-term administration of Hypericum perforatum can improve learning and spatial memory with significant changes in the content of monoamines in several brain regions.