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  • Author: Ivanka I. Kostadinova x
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Effect of Atorvastatin and Rosuvastatin on Learning and Memory in Rats with Diazepam-Induced Amnesia

ABSTRACT

During the past decade, evidence has emerged that statins have neuroprotective effects.

AIM: The aim of this study was to investigate the effects of atorvastatin and rosuvastatin on learning and memory in rats with diazepam-induced amnesia.

MATERIAL AND METHODS: Experiments were carried out on 48 white male Wistar rats, divided into 6 groups, each of 8 rats. The experimental animals were treated per os for 14 days with atorvastatin and rosuvastatin in doses of 10 mg/kg and 20 mg/kg body weight, respectively. To induce amnesia diazepam was administered intraperitoneally in a dose of 2.5 mg/kg bw. Cognitive skills of the animals were examined after the induction of amnesia with active avoidance test using autonomic reflex conditioner (shuttle box) and passive avoidance tests (step-through and step down) (Ugo Basile, Italy). The following parameters were assessed: number of conditioned responses (avoidances), number of unconditioned responses (escapes) and number of intertrial crossings in the active avoidance test; latency of reactions was measured in the passive avoidance tests.

RESULTS: We found a significant increase of conditioned responses in atorvastatin treated animals (in a dose of 10 mg/kg bw) in active avoidance training. In the animals treated with rosuvastatin in both doses there was a statistically significant increase of unconditioned responses. In the step-through passive avoidance test there was significant improvement of short-term and long-term memory following administration of atorvastatin (10 mg/kg bw). Rosuvastatin (10 mg/kg bw) preserves long-term memory. In the step-down passive avoidance test, atorvastatin (10 mg/kg bw) and rosuvastatin (10 mg/kg bw and 20 mg/kg bw) preserve long-term memory.

CONCLUSIONS: Atorvastatin (10 mg/kg bw) and rosuvastatin (10 mg/kg and 20 mg/kg bw) improve cognitive functions in rats with diazepam-induced amnesia and preserve longterm memory.

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Antinociceptive Effect of Clomipramine Through Interaction with Serotonin 5-Нт2 And 5-Нт3 Receptor Subtypes

Abstract

INTRODUCTION: Tricyclic antidepressants are used in the treatment of various pain syndromes. The antidepressant clomipramine inhibits predominantly the reuptake of serotonin in the central nervous system. The mechanism of its analgesic effect is not fully understood.

The AIM of the present study was to find experimentally any dose-effect dependence in the analgesic effect of clomipramine and the involvement of the 5-НТ2 and 5-НТ3 receptors in the mechanism of this effect. Material and methods: Fifty male Wistar rats were used in the study allocated to five groups (10 animals each): a saline treated control group, one positive control group treated with metamizole and three experimental groups treated with intraperitoneally administered clomipramine in doses of 5, 10 and 20 mg/kg bw, respectively. To study the role of 5-НТ2 and 5-НТ3 receptors in this effect we used another five groups (10 animals each): control, positive control and three experimental groups treated with clomipramine only, clomipramine and granisetrone and clomipramine and cyproheptadine, respectively. Three nociceptive tests were used: the hot plate test, analgesimeter and the acetic acid-induced writhing test. To gauge the antinociceptive action we used the increased latency in the hot plate test expressed as maximum possible effect % (%MPE), the increase in paw pressure to withdraw the hind paw in analgesimeter and decrease in the number of spinal cord writhes in the acetic acid test.

RESULTS: Clomipramine in a dose of 20 mg/kg bw significantly increased the %MPE in hot plate test and the pressure to withdraw the hind paw in the analgesimeter when compared with the control. In the acetic acid test clomipramine decreased non-significantly the number of writhes compared with the controls. Granisetrone reduced non-significantly the antinociceptive effect of clomipramine in all tests. Cyproheptadine potentiated the analgesic effect of clomipramine in acetic acid test and decreased it significantly in the hot plate test. In analgesimeter cyproheptadine decreased significantly the paw pressure to withdraw the tested hind paw at 1 hour and non-significantly at 2 hours.

CONCLUSION: Clomipramine in the dose of 20 mg/kg bw has a pronounced antinociceptive affect towards thermal and mechanical pain stimulation. The 5-HT2 and 5-HT3 receptor subtypes are very likely involved in the mechanism of this effect.

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Effects of Long-Term Treatment with Atorvastatin and Rosuaastatin on Active Avoidance Test in Intact Rats

Summary

Statins are widely used for treatment of hyperlipidemia. They have been shown to possess pleiotropic effects apart from their lipid-lowering activity - anti-inflammatory, immunomodulatory, and neuroprotective. Most studies suggest that statins can protect the brain against damage but it is not clear whether they improve cognitive function in patients without neuropathy. The aim of the present study was to investigate the effect of 3-month treatment with atorvastatin and rosuvastatin on learning and memory processes in rats without brain damage. Wistar rats were treated orally for 90 days with atorvastatin and rosuvastatin at a dose of 10 mg/kg b. w. in parallel with the vehicle-treated group. After that period, learning ability and memory retention was evaluated using an active avoidance test - automatic reflex conditioner (shuttle box). The learning session was carried out on 5 consecutive days. Memory retention test was performed on day 12. The following behavioral reactions were investigated: conditioned responses (avoidance), unconditioned responses (escapes), and intertrial crossings. We found increased number of conditioned responses in groups, treated with atorvastatin 10 mg/kg b.w., and with rosuvastatin 10 mg/kg b.w. during the learning session and on the memory retention test, as compared to the same-day control group. The atorvastatin-treated group showed an increased number of unconditioned responses on days 1 and 2, as compared to the control group. In the group treated with Rosuvastatin there was an increased number of escapes on days 1,2 and 4, as compared to the vehicle-treated group. Atorvastatin and rosuvastatin at a dose of 10 mg/kg b.w. improved processes of learning and memory retention after the 3-month treatment.

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Effect of Testosterone Propionate on Erythropoiesis after Experimental Orchiectomy

ABSTRACT

INTRODUCTION: Androgen deficiency anemia occurs most frequently in pharmacogenic suppression of androgen synthesis or with advancing age in men. Bilateral orchiectomy is a surgical modality used in the treatment of metastatic prostate carcinoma. It is accompanied by marked decrease in circulating serum levels of androgens. AIM: The aim of the experimental study was to determine the effect of substitution therapy with testosterone propionate (TP) on some haematological parameters of erythropoiesis in male rats after orchiectomy.

MATERIAL AND METHODS: Eighty Wistar male rats with mean weight of 252.3 g were used in the study. The animals were allocated into 2 control orchidectomized groups, 2 shamoperated groups and 4 experimental orchidectomized groups. Testosterone propionate was administered intramuscularly, once a week at a dose of 4 mg and 8 mg per kilogram of body weight for 15 days and for 15 weeks. Erythrocyte count was performed and hemoglobin and hematocrit levels were measured.

RESULTS: In the chronic experiment there was a significant decrease in red blood cells and hemoglobin, and a tendency of decrease in hematocrit after orchiectomy. The effect of TP on erythropoiesis in orchiectomised rats is dose-dependent.

CONCLUSION: TP replacement therapy in doses of 4 mg/kg and 8 mg/kg has a stimulating effect on erythropoiesis only in chronic administration.

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Experimental Study on the Role of 5-Ht2 Serotonin Receptors in the Mechanism of Anti-Inflammatory and Antihyperalgesic Action of Antidepressant Fluoxetine

ABSTRACT

INTRODUCTION: Fluoxetine is an antidepressant that has anti-inflammatory and antihyperalgesic effects in experimental models of pain and inflammation. The AIM of the present study was to determine the role of 5-HT2 receptors in the mechanism of anti-inflammatory and antihyperalgesic action of fluoxetine after single and repeated administration of the drug. MATERIALS AND METHODS: 40 male Wistar rats were randomly divided in five groups (n = 8) treated for 14 days with saline (control), diclofenac (positive control), fluoxetine, cyproheptadine (5-HT2 antagonist), and fluoxetine + cyproheptadine, respectively. We used the experimental model of inflammation induced by intraplantar injection of carrageenan and nociceptive test with mechanical pressure on the inflamed hind paw. RESULTS: Single and repeated administration of fluoxetine showed that it had significant anti-inflammatory and antihyperalgesic effects when compared with the control (p < 0.05). Cyproheptadine did not change significantly the anti-inflammatory effect of fluoxetine in the first 4 hours, after a single administration. At 24 hours the combination did not differ statistically when compared with the control. Cyproheptadin did not change significantly the anti-inflammatory effect of fluoxetine after repeated administration. After prolonged treatment the group that received fluoxetine + cyproheptadine showed a statistically significant increase in paw pressure to withdraw the hind paw compared with that treated with fluoxetine alone (p < 0.05). CONCLUSIONS: Fluoxetine has anti-inflammatory and antihyperalgesic effects in the carrageenan model of inflammation. 5-HT2 receptor mediated its anti-inflammatory effect in single dose treated animals. Spinal 5-HT2 receptors are involved in the antihyperalgesic effect of fluoxetine after repeated administration

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A Prospective Study on 25 Hydroxyvitamin D Serum Levels in Patients with Relapsing-Remitting Multiple Sclerosis

Abstract

To assess the changes in the serum concentrations of 25(ОH)D in relapse and remission and their relation to the degree of neurological deficit. We analyzed 53 subjects (30 controls and 23 patients) from October 2012 to Маy 2013. Diagnosis was based on McDonald 2010 criteria. The severity of neurological deficit was assessed by the Expanded Disability Status Scale. Serum concentrations of 25(ОH)D (nmol/l) were measured by ELISA once in controls and twice in patients - in relapse and remission. Mean levels in all groups were in the mild to moderate deficiency range, being lowest in the patients in relapse (controls 31.46±7.3; relapse 26.93±7.44; remission 28.06±7.28). There was a trend for lower levels of 25(ОH)D in healthy females in comparison to their male counterparts, and in female patients in relapse as compared to males (female controls - 26.56±8.4, male controls - 41.35±11.86; females in relapse - 26.33±10.03, males in relapse - 28.06±11.08). Negative statistically significant correlations between the concentrations of 25(ОH)D during relapse and remission and the degree of neurological deficit in the corresponding period were found (cc. -0.593, Sig 0.03, relapse; -0.46, Sig 0.024, remission). Assessment of the risk for development of MS, regarding the 25(ОH)D showed protective effect with respect to the risk of disease occurrence (ОR: 04125 relapse; 0.578 remission).

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25 Hydroxyvitamin D and Cytokines in Multiple Sclerosis

Abstract

INTRODUCTION: Clinical trials of patients with multiple sclerosis (MS) have produced inconsistent results for the profile of cytokine secretion in serum and cerebrospinal fluid in patients with multiple sclerosis during periods of relapse and remission. Epidemiological and clinical observations data reveal an association of the changes in vitamin D serum concentration with the risk of developing MS. AIM: To evaluate changes in serum concentrations of 25(OH)D, IL17, IFN-gamma, TGFβ1, IL4, IL10 in relapse and remission and their correlation with the severity of disability. PATIENTS AND METHODS: Fifty-three persons (30 clinically healthy controls and 23 patients with relapsing-remitting multiple sclerosis) living between 41° and 42° northern latitude were registered during the astronomical winter period (October 2012- May 2013). -Patients were diagnosed according to Mc Donald 2010 criteria. The degree of neurological deficit was assessed by EDSS. Serum concentrations of 25(OH)D (nmol/l) and cytokines (pg/ml) were tested by ELISA - once for controls and twice for patients (during relapse and remission). RESULTS: In the studied population average levels of 25(OH)D were close to insufficiency, most pronounced in patients in relapse, as differences were not statistically significant. A reverse correlation was found between the levels of 25(OH)D and the deficit in relapse and remission. Concentrations of TGFβ1 significantly increased in remission compared with exacerbation and controls. Serum level of IL4 was significantly lower in relapse compared with controls. In remission there was a marked tendency of increase compared with exacerbation. During clinical improvement IL17 and IFN-gamma tended to decrease compared to the average levels in relapse. In both periods, the average concentrations of IFN-gamma in patients were significantly lower compared with controls. No statistically significant differences were found comparing cytokine changes with those of 25(OH)D and deficit. CONCLUSION: Persistent cytokine imbalance in patients compared with controls is a marker for Th1-mediated CNS demyelination. Anti-inflammatory TGFβ1, IL4 are indicators of immune response intensity. The deficit severity does not depend on changes of the tested cytokines, but correlates with 25(OH)D levels during periods of relapse and remission.

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Vitamin D Immunomodulatory Potential in Multiple Sclerosis

ABSTRACT

Multiple sclerosis (MS) is an autoimmune disease of unknown etiology whose treatment is of limited efficiency and therefore has a high social burden. As it has been suggested that myelin destruction model, the clinical manifestation and the potential of therapeutic response in MS are correlated, it is quite justifiable that we study various factors (genetic, hormonal, environmental) that take part in the autoimmune process in order to improve the control over the disrupted immune regulation. Results from epidemiological and clinical studies clearly suggest that changes in vitamin D serum concentrations are correlated with the magnitude of the risk of developing MS, the phases of relapse and remittance and with gender differences in vitamin D metabolism. Experimental and clinical studies also have established that 25-hydroxy vitamin D (25(OH)D) and 1,25-dihydroxy vitamin D (1,25(OH)2D) exert an immunomodulatory effect in the central nervous system and peripheral organs of the immune system. The standard reference range of vitamin D concentration in serum is 50-80 nmol/l - it provides normal calcium metabolism. Issues that are discussed include the vitamin D serum concentration needed to suppress the aberrant immune response in MS patients; a subgroup of MS patients suitable for vitamin D treatment, the vitamin D being applied in optimally effective and safe dosage. MS prevalence rate in Bulgaria has increased two-fold in 17 years but this is a rather short interval to be able to assume that the gene pool of the population changes. Thus further studies on possible interactions between different environmental factors and these factors’ role in the disease pathogenesis are justified and necessary.

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Clinical and laboratory study of pro-inflammatory and anti-inflammatory cytokines in women with multiple sclerosis

Abstract

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system characterised with a complex system of interactions between proinflammatory and anti-inflammatory cytokines in its course.

Aim: The aim of the present study was to investigate the serum levels of cytokines TNF-α, IFN- γ, IL- 4 and IL- 10 in female patients with MS and healthy individuals, the changes occurring in the relapse and remission phases of the disease and their correlation with the severity of the neurological deficit.

Patients and methods: Thirty-five women with relapsing-remitting MS were examined. The patients’ age ranged between 18 and 50 years and MS was verified clinically and by magnetic resonance imaging according to the McDonald criteria. Thirteen of the patients were treated with interferon-β-1b. The serum concentrations of TNF-α, IFN- γ, IL- 4 and IL- 10 were determined twice - in relapse and in remission - using an enzyme-linked immunosorbent assay (EL ISA). The control group consisted of 35 age-matched healthy females. Results: The comparison of cytokine serum concentrations during the two phases of the disease showed significant elevation of the TNF-α serum levels in the relapse phase and of IL- 4 - in the remission phase. The comparison between the patients and the healthy control subjects demonstrated statistically significant lower concentrations of TNF-α in remission patients and higher concentrations of IL- 10 in relapse patients. The patients with interferon-β-1b treatment showed different profile of cytokine secretion from the patients without interferon-β-1b treatment. Interferon-β-1b-treated patients showed significantly lower serum levels of TNF-α and IFN- γ during the relapse phase and higher TNF-α and IL- 10 serum levels during the remission phase compared with the untreated patients.

Conclusions: Serum levels of TNF-α and IL- 4 objectively reflect the immune response during relapse and remission of the disease. The severity of neurological deficit as estimated with the expanded disability status scale (EDSS ) does not depend on the serum levels of TNF-α, IL- 10 and IFN- γ in the two phases of MS.

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Antidepressant Effect and Recognition Memory Improvement of Two Novel Plant Extract Combinations - Antistress I and Anti-stress II on Rats Subjected to a Model of Mild Chronic Stress

Abstract

Background: Chronic stress is one of the main factors which lead to depression – a psychiatric disorder affecting millions of people and predicted to be the second ranked cause of premature death in 2020. Depression is often associated with cognitive disturbances and memory deficit. Plant based therapy could be effective in the treatment of mild to moderate depression due to its low level of adverse reaction, its good tolerability and compliance.

Materials and methods: 72 male Wistar rats, divided in 9 groups were given orally for 8 weeks two combinations of dry plant extracts – Antistress I and Antistress II and five individual dry extracts obtained from Serratula coronata, Hypericum perforatum, Valeriana officinalis, Crataegus monogyna and Melissa officinalis. The animals were exposed to a chronic unpredictable mild stress for 8 weeks. The depression-like symptoms were evaluated with Forced swim test while the assessment of the memory deficit was performed with Novel object recognition test.

Results: Antistress II demonstrates antidepressant effect while Antistress I doesn’t improve the depressive-like symptoms. The individual extracts of Hypericum perforatum and Valeriana officinalis also possess antidepressant properties. Antistress II improves the cognition as well as the individual extracts of Hypericum perforatum, Valeriana officinalis and especially Serratula coronata. Dry extract from Serratula tend to have the best effect regarding the recognition memory. The effect of Antistress I on memory deficit is negligible.

Conclusions: Antistress II possesses antidepressant effect and improves the recognition memory while Antistress I doesn’t demonstrate any of the above-described effects.

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