Pivaloylcodeine, a new codeine derivative, for the inhibition of morphine glucuronidation. An in vitro study in the rat.

We have previously found that phenanthrenic opioids, including codeine, modulate morphine glucuronidation in the rat. Here codeine and five of its derivatives were compared in their effects on the synthesis of morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) from morphine by rat liver microsomal preparations, and by primary cultures of rat hepatocytes previously incubated for 72 h with either codeine or its derivatives. Acetylcodeine and pivaloylcodeine shared the capability of the parent compound of inhibiting the synthesis of M3G by liver microsomes through a noncompetitive mechanism of action. Their IC50 were 3.25, 2.27, and 4.32 µM, respectively. Dihydrocodeine, acetyldihydrocodeine, and lauroylcodeine were ineffective. In all the experimental circumstances M6G was undetectable in the incubation medium. In primary hepatocyte cultures codeine only inhibited M3G formation, but with a lower efficacy than that observed with microsomes (IC50 20.91 vs 4.32 µM). Preliminary results show that at micromolar concentrations codeine derivatives exhibit a low rate of affinity for µ opiate receptors. In conclusion, acetyl and pivaloyl derivatives of codeine noncompetitively inhibit liver glucuronidation of morphine interacting with microsomes. This study further strengths the notion that phenanthrenic opioids can modulate morphine glucuronidation independently from their effects on µ opiate receptors.

In vitro morphine metabolism by rat microglia.

Morphine is mainly transformed to morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) in the liver. Glucuronidation is also performed by rat brain homogenates and UDP-glucuronosyltransferases (UGTs) are present in the brain. Here we investigated the possibility that microglia transforms morphine into its metabolites M3G and M6G. Primary cultures of neonatal rat microglia were incubated for different intervals of time in basal conditions or with different concentrations of morphine. The following measures were performed on these cultures and/or in the medium: (i) morphine as well as M3G and M6G concentrations; (ii) levels of mRNA coding for UGT1A1, UGT1A6, UGT1A7, and UGT2B1 as well as their protein levels; (iii) released prostaglandin (PG)E2 and nitrite concentrations. Results show that in basal conditions morphine and M3G are produced by microglia; accordingly, these cells expressed UGT1A1, UGT1A6 and UGT1A7, but not UGT2B1. When cultures were exposed to different concentrations of exogenous morphine, M6G was also synthesized. This shift in the glucuronidation was associated with variations in the expression of UGT isozymes. In particular, UGT1A7 expression was rapidly upregulated and this event was translated into enhanced protein levels of UGT1A7; lesser effects were exerted on UGT1A1 and UGT1A6. Upon prolonged exposure to morphine, microglial cell UGT expression returned to baseline conditions or even to reduced levels of expression. Morphine exposure did not affect the synthesis of both PGE2 and nitrites, ruling out a generalized priming of microglia by morphine. In conclusion, this study suggests that morphine glucuronides found in the cerebrospinal liquor upon peripheral morphine administration may at least in part be brain-born, reconciling the conceptual gap between the high hydrophilic features of morphine glucuronides and their presence beyond the blood-brain barrier.

1-Phenil-6,7-dihydroxy-isochroman inhibits inflammatory activation of microglia.

Inflammation plays a central role in the pathogenesis of several brain disorders and neuronal injury, and it develops as a consequence of glial cell activation. Activated microglial cells generate potentially damaging nitric oxide, oxygen free radicals, prostanoids, and pro-inflammatory cytokines. Naturally occurring polyphenols have recently received attention for their potential protective effect on neurodegenerative disorders characterized by microglial activation, due to their anti-inflammatory and antioxidant properties. In the present study, we investigated, using an in vitro model of primary microglia, the ability of 1-phenyl-6,7-dihydroxy-isochroman (encoded L 137), a natural polyphenolic compound, to inhibit microglia activation induced by an inflammatory insult. So, L137 effects (1-100 µM) on production of pro-inflammatory mediators in lipopolysaccharide (LPS)-activated microglial cells were evaluated. The expression of inducible isoforms of nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) as well as of the nuclear transcription Factor-kappa B (NF-κB) was also performed in cellular lysates by Immunoblot. L137 significantly reduced tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6 secretion, as well as nitric oxide (NO) and prostanoids [Thromboxane (TX)B2, prostaglandin (PG)E2] production in activated microglial cells. Western blot analyses showed an inhibitory effect of L137 on the iNOS and COX-2 expression, mediated by a modulation of redox-sensitive nuclear transcriptional factor (NF)-κB, known to control a wide array of genes involved in inflammation. In conclusion, this study demonstrate that L137 is able to inhibit the production of pro-inflammatory and neurotoxic mediators by LPS-activated microglial cells thus suggesting L137 as a potential lead compound for drug development for neurodegenerative disorders where microglia-mediated inflammatory responses play an important pathogenic role.

Highly electroconductive multiwalled carbon nanotubes as potentially useful tools for modulating calcium balancing in biological environments.

Aiming to explore the mechanisms modulating cell-carbon nanotube interactions, we investigated whether Ca(2+) ion balancing between intra- and extracellular environments could be affected by multiwalled carbon nanotubes (MWCNTs). We analyzed the effects induced by two different kinds of MWCNTs (as prepared and annealed at 2400°C) on the intracellular Ca(2+) ion levels in rat electrically sensitive cells and on the intercellular junction integrity of rat adenocarcinoma colon cells and platelet aggregation ability, which depend on the Ca(2+) concentration in the medium. MWCNTs, purified by annealing and more electroconductive as compared to nonannealed MWCNTs, affected Ca(2+) ion balancing between extra- and intracellular environments and induced changes on Ca(2+) ion-dependent cellular junctions and platelet aggregation, behaving as the calcium chelator ethylene glycol tetraacetic acid. This could be due to the sorption of cationic Ca(2+) ions on CNTs surface because of the excess of negatively charged electrons on the aromatic units formed on MWCNTs after annealing. From the ClinicAL Editor: The authors investigated whether Ca(2+) ion balance between intra- and extracellular space can be modulated by multiwalled carbon nanotubes (MWCNTs). Annealed nanotubes induced changes on Ca(2+) dependent cellular junctions and platelet aggregation, behaving similary to ethylene glycol tetraacetic acid, an established calcium chelator.

1-Phenyl-6,7-dihydroxy-isochroman suppresses lipopolysaccharide-induced pro-inflammatory mediator production in human monocytes.

Extra-virgin olive oil is an integral ingredient of the Mediterranean diet, and it has been suggested that its high consumption has beneficial effects on human health. Its protective effect, in particular against the development of CVD, has been related not only to the high content of oleic acid, but also to the antioxidant and anti-inflammatory properties of polyphenols. In order to verify the anti-inflammatory and anti-atherogenic properties of hydroxy-isochromans, a class of ortho-diphenols present in extra-virgin olive oil, we investigated the potential ability of 1-phenyl-6,7-dihydroxy-isochroman (L137) to modulate the production of key inflammatory mediators by human monocytes, by evaluating its in vitro effects on prostanoid (thromboxane A(2) and PGE(2)) and cytokine (TNF-α) production. Its effect on the protein expression of the inducible form of cyclo-oxygenase-2 (COX-2), a pro-inflammatory enzyme responsible for elevated prostanoid levels, was also explored. The results showed that L137 significantly inhibited both prostanoid and TNF-α production in lipopolysaccharide-primed human monocytes in a dose-dependent manner, by inhibiting the COX activity of COX-2. We also demonstrated that the effects of the isochroman are mediated, at least partly, through the suppression of NF-κB activation leading to the down-regulation of the synthesis of COX-2.

Repeated anabolic androgenic steroid treatment causes antidepressant-reversible alterations of the hypothalamic-pituitary-adrenal axis, BDNF levels and behavior.

Abuse of anabolic androgenic steroids (AASs) is frequently associated with changes in mood, including depression. However, the nature of this association is still largely unexplored. As a model of AAS abuse, we used male adult rats injected for 4 weeks with either nandrolone or stanozolol at daily doses (5 mg/kg, s.c.) that are considered equivalent to those abused by humans on a milligram per kilogram of body weight basis. AAS treatment reduced levels of brain-derived neurotrophic factor in the hippocampus and prefrontal cortex, reduced the expression of low-affinity glucocorticoid receptors in the hippocampus, and increased morning trough basal plasma corticosterone levels. All these changes have been related to the pathophysiology of major depressive disorder. Accordingly, rats treated with nandrolone or stanozolol showed an increased immobility time in the forced swim test, which is widely used for the screening of antidepressant drugs. All effects produced by AASs were prevented by co-administration with the classical antidepressant, chlorimipramine. The evidence that supraphysiological doses of AASs induce changes indicative of a depressive state in normal rats, raises the concern that AAS abuse in humans may cause depression regardless of exposure to stress or other risk factors.

Cigarette smoke inhibits adenine nucleotide hydrolysis by human platelets.

Cigarette smoking is a recognized risk factor for cardiovascular diseases and has been implicated in the pathogenesis of atherosclerosis and thrombotic events. In athero-thrombotic diseases, the extracellular adenine nucleotides play an important role by triggering a range of effects such as the recruitment and activation of platelets, endothelial cell activation and vasoconstriction. NTPDase, a plasma membrane-bound enzyme, is the most relevant enzyme involved in the hydrolysis of extracellular tri- and di-phosphate nucleotides to adenosine monophosphate, which is further degraded by 5'ectonucleotidase to the anti-thrombotic and anti-inflammatory mediator adenosine. Thus, the preserved activity of these enzymes, regulating the extracellular concentrations of nucleotides, is critical in thromboregulatory functions. In the present in vitro study, performed on human platelets suspended in undiluted or diluted aqueous cigarette smoke extract (aCSE), we demonstrated that undiluted and 1 : 2 diluted aCSE is able to significantly reduce ADP hydrolysis (-24% and 12%, respectively) by intact human platelets. ATP degradation was also reduced (-31%) by undiluted aCSE. Conversely, aCSE did not alter platelet AMP hydrolysis. Results obtained by using N-acetylcysteine, a thiol-containing antioxidant, suggest that stable oxidants present in aCSE are responsible for the platelet NTPDase inhibition induced by aCSE. The decreased adenine nucleotide degradation could play a significant role in the extensive platelet activation and vascular inflammation observed in chronic smokers.

Olive oil isochromans inhibit human platelet reactivity.

The effects of certain polyphenolic compounds in red wine, such as resveratrol and quercetin, have been widely investigated to determine the relationship between dietary phenolic compounds and the decreased risk of cardiovascular diseases. However, the effects of polyphenolic compounds contained in other foods, such as olive oil, have received less attention and little information exists regarding the biological activities of the phenol fraction in olive oil. The aim of this study was to evaluate the antiplatelet activity and antioxidant power of two isochromans [1-(3'-methoxy-4'-hydroxy-phenyl)-6,7-dihydroxy-isochroman (encoded L116) and 1-phenyl-6,7-dihydroxy-isochroman (encoded L137)] recently discovered in olive oil and synthesized in our laboratory from hydroxytyrosol. These compounds were effective free radical scavengers and inhibited platelet aggregation and thromboxane release evoked by agonists that induce reactive oxygen species-mediated platelet activation including sodium arachidonate and collagen, but not ADP. Release of tritiated arachidonic acid from platelets was also impaired by L116 and L137. These results indicate that other Mediterranean diet nutraceuticals also exhibit antioxidant activity that could be beneficial in the prevention of vascular diseases.

Testosterone and cocaine: vascular toxicity of their concomitant abuse.

Over the last few years, several studies have described an increase in the use of anabolic-androgenic steroids (AAS). More important, frequency of AAS use was significantly associated with frequency of psychotropic drug use, such as cocaine. Since information is not available on the effects of their concomitant abuse, and taking into account that cocaine and testosterone, when singly abused, are known to induce severe adverse effects on vascular system, our purpose was to evaluate in vitro the combined effect of these drugs on platelet and endothelial functions. Results show that testosterone, at concentrations not exerting any appreciably acute effects on their own, is capable of potentiating the cocaine effect on endothelial and platelet functions, indicating that concomitant use of testosterone and cocaine could result in enhancement of the thrombotic risk ascribed to these drugs.