The cognition-enhancing activity of E1R, a novel positive allosteric modulator of sigma-1 receptors

Background and Purpose Here, we describe the in vitro and in vivo effects of (4R,5S)-2-(5-methyl-2-oxo-4-phenyl-pyrrolidin-1-yl)-acetamide (E1R), a novel positive allosteric modulator of sigma-1 receptors. Experimental Approach E1R was tested for sigma receptor binding activity in a [3H](+)- pentazocine assay, in bradykinin (BK)-induced intracellular Ca2+ concentration ([Ca2+]i) assays and in an electrically stimulated rat vas deferens model. E1R's effects on cognitive function were tested using passive avoidance (PA) and Y-maze tests in mice. A selective sigma-1 receptor antagonist (NE-100), was used to study the involvement of the sigma-1 receptor in the effects of E1R. The open-field test was used to detect the effects of E1R on locomotion. Key Results Pretreatment with E1R enhanced the selective sigma-1 receptor agonist PRE-084's stimulating effect during a model study employing electrically stimulated rat vasa deferentia and an assay measuring the BK-induced [Ca2+]i increase. Pretreatment with E1R facilitated PA retention in a dose-related manner. Furthermore, E1R alleviated the scopolamine-induced cognitive impairment during the PA and Y-maze tests in mice. The in vivo and in vitro effects of E1R were blocked by treatment with the selective sigma-1 receptor antagonist NE-100. E1R did not affect locomotor activity. Conclusion and Implications E1R is a novel 4,5-disubstituted derivative of piracetam that enhances cognition and demonstrates efficacy against scopolamine-induced cholinergic dysfunction in mice. These effects are attributed to its positive modulatory action on the sigma-1 receptor and this activity may be relevant when developing new drugs for treating cognitive symptoms related to neurodegenerative diseases.publishersversionPeer reviewe

NEW PATHOGENETIC FACTORS OF ATHEROSCLEROSIS DEVELOPMENT AND POTENTIAL THERAPEUTIC APPROACHES

It has been demonstrated that one of the factors in the pathogenesis of atherosclerosis, with the subsequent development of myocardial infarction (MI), stroke (S), or sudden death (SD), is trimethylaminoxide (TMAO), the end-product of dietary choline, betaine, or carnitine metabolism by intestinal microflora. Simultaneously elevated levels of TMAO and carnitine are associated with a doubled or even tripled risk of MI, S, and SD. Therefore, dietary intake of choline-rich phosphatidylcholine fats and red meats and carnitine-rich dairy is an important risk factor (RF) of atherosclerosis. At the moment, there is no universally accepted therapeutic approach which reduces TMAO and carnitine levels. The only agent which can simultaneously reduce the levels of these two atherosclerosis-associated RFs is a well-known cardio- and cytoprotector Mildronate. Experimental and pilot clinical studies of Mildronate effectiveness in patients with obliterating atherosclerosis suggest the need for further, more detailed clinical trials of Mildronate, for estimation of its efficacy and safety

Матер. III съезда фармакологов России, 23-27 сентября 2007 г. (Тез 533)

Pupure J., Fernandes M.A.S., Oliveira C.R., Moreno A.J.M., Santos M.S., Kalvinsh I., Isajevs S., Klusa V. Mitochndria-regulating effects of mildronate in azidothymidine-induced toxicity Proceedings of the III Congress of Pharmacology Russia, Saint-Petersburg, 23–27 September 2007. Abstr 533. Psychopharmacol Biol Narcol 2007 Sept; 7 Suppl (Pt 2, M–Ja): 2-1911–2-1911 [in English]AZT (azidothymidine) is the first antiMHIV drug used in AIDS treatment, and it is still most commonly used in drug combinations. AZT inhibits polymerase g which is responsible for HIVM1 mitochondrial DNA replication, changes the structure of mitochondria by its incorporation into mitochondria [Peters et al., 1993]. Therefore the use of AZT is limited due to its severe side effects — myopathies, especially cardiomyopathies, lipodystrophy, hepatic steatosis, lactic acidosis and others [Badley et al., 2003]. We have suggested that AZTMinduced toxicity may be prevented by drugs capable of regulating mitochondrial processes. Hence, we have used mildronate, a cardioprotective drug of azaMbutyrobetaine class, which was shown to protect rat heart mitochondria from free fatty acid detergentMlike action by inhibiting carnitine palmitoyl transferase 1 [Dambrova et al., 2002]. Besides, mildronate protects the energy metabolism against the H2O2Minduced derangement in isolated rat heart (Akahira et al., 1997) and improves cardiac sarcoplasmic reticulum Ca2+ uptake activity [Hayashi et al., 2000]. In the present study, AZT and mildronate were administered in male mice intraperitoneally, per se and in combinations during a twoMweek period at doses previously found as the most active ones: AZT 50 mg/kg, and mildronate 50, 100 and 200 mg/kg. After termination of drug administration, mice were sacrificed and their heart and brain tissue were removed. Immunohistochemical assessment of nuclear factor kappa B (NFMkBp65) in the heart, and morphological assessment of heart and brain tissue was performed. The obtained results showed that AZT treatment significantly increased NFMkBp65 expression, indicating manifestation of oxidative stress leading to mitochondrial damage. AZT caused also morphological — inflammatory and degenerative — alterations in mice heart tissue. In brain tissue AZT caused degeneration of neurons in the molecular layer and external granular layer. Mildronate in combination with AZT reduce these AZTMinduced pathologic actions both in heart and brain tissue, demonstrating its powerful protective action. One may suggest that mildronate’s protective activity is provided via targeting mitochondrial processes. That indicates usefulness of mildronate’s combination with antiMHIV and other mitochondriaMcompromized drugs.  Pupure J., Fernandes M.A.S., Oliveira C.R., Moreno A.J.M., Santos M.S., Kalvinsh I., Isajevs S., Klusa V. . Матер. III съезда фармакологов России. Психофармакол биол наркол 2007 Спец Вып; 7 (Ч 2, М–Я): 2-1911–2-1911 (Тез 533

EPR investigation of in vivo inhibitory effect of guanidine compounds on nitric oxide production in rat tissues

The aim of the present study was to evaluate in vivo effects on NO production of pharmacologically widely used, commercially available NOS inhibitors, structurally related to guanidine. We compared the NO inhibitory potency and selectivity of L-NAME, aminoguanidine and guanabenz in tissues of normal and LPS-stimulated rats using ex vivo EPR measurements of the NO radical in its complex with dithiocarbamate-Fe(II). The tissues studied were the brain cortex, kidney, liver, heart and testis. Differential inhibitory effects were seen for L-NAME, aminoguanidine and guanabenz when applied during basal or LPS-stimulated conditions. Aminoguanidine exerted inhibition of NO only after stimulation with LPS. Guanabenz had little effect on NO in liver, kidney, testis and heart under normal conditions, while it reduced the basal NO in brain cortex. After stimulation with LPS guanabenz afforded a partial inhibition of the NO formation in all tissues studied. L-NAME was a potent inhibitor of NO synthesis in all tested tissues, both during basal and LPS stimulated conditions. Our results show that compounds containing a guanidine moiety might possess different NOS inhibitory profiles in vivo.publishersversionPeer reviewe

Матер. III съезда фармакологов России, 23-27 сентября 2007 г. (Тез 533)

Pupure J., Fernandes M.A.S., Oliveira C.R., Moreno A.J.M., Santos M.S., Kalvinsh I., Isajevs S., Klusa V. Mitochndria-regulating effects of mildronate in azidothymidine-induced toxicity Proceedings of the III Congress of Pharmacology Russia, Saint-Petersburg, 23–27 September 2007. Abstr 533. Psychopharmacol Biol Narcol 2007 Sept; 7 Suppl (Pt 2, M–Ja): 2-1911–2-1911 [in English]AZT (azidothymidine) is the first antiMHIV drug used in AIDS treatment, and it is still most commonly used in drug combinations. AZT inhibits polymerase g which is responsible for HIVM1 mitochondrial DNA replication, changes the structure of mitochondria by its incorporation into mitochondria [Peters et al., 1993]. Therefore the use of AZT is limited due to its severe side effects — myopathies, especially cardiomyopathies, lipodystrophy, hepatic steatosis, lactic acidosis and others [Badley et al., 2003]. We have suggested that AZTMinduced toxicity may be prevented by drugs capable of regulating mitochondrial processes. Hence, we have used mildronate, a cardioprotective drug of azaMbutyrobetaine class, which was shown to protect rat heart mitochondria from free fatty acid detergentMlike action by inhibiting carnitine palmitoyl transferase 1 [Dambrova et al., 2002]. Besides, mildronate protects the energy metabolism against the H2O2Minduced derangement in isolated rat heart (Akahira et al., 1997) and improves cardiac sarcoplasmic reticulum Ca2+ uptake activity [Hayashi et al., 2000]. In the present study, AZT and mildronate were administered in male mice intraperitoneally, per se and in combinations during a twoMweek period at doses previously found as the most active ones: AZT 50 mg/kg, and mildronate 50, 100 and 200 mg/kg. After termination of drug administration, mice were sacrificed and their heart and brain tissue were removed. Immunohistochemical assessment of nuclear factor kappa B (NFMkBp65) in the heart, and morphological assessment of heart and brain tissue was performed. The obtained results showed that AZT treatment significantly increased NFMkBp65 expression, indicating manifestation of oxidative stress leading to mitochondrial damage. AZT caused also morphological — inflammatory and degenerative — alterations in mice heart tissue. In brain tissue AZT caused degeneration of neurons in the molecular layer and external granular layer. Mildronate in combination with AZT reduce these AZTMinduced pathologic actions both in heart and brain tissue, demonstrating its powerful protective action. One may suggest that mildronate’s protective activity is provided via targeting mitochondrial processes. That indicates usefulness of mildronate’s combination with antiMHIV and other mitochondriaMcompromized drugs.  Pupure J., Fernandes M.A.S., Oliveira C.R., Moreno A.J.M., Santos M.S., Kalvinsh I., Isajevs S., Klusa V. . Матер. III съезда фармакологов России. Психофармакол биол наркол 2007 Спец Вып; 7 (Ч 2, М–Я): 2-1911–2-1911 (Тез 533