Administration of lithium and magnesium chloride inhibited tolerance to the anticonvulsant effect of morphine on pentylenetetrazole-induced seizures in mice

The Influence of Lithium and/or Selenium Treatment on Homeostasis of Chosen Bioelements in Rats

Lithium is widely used in medicine and the therapy is often long term. Apart from beneficial effects, its application can cause diverse side effects. The current study was performed with the aim of the evaluation of the effect of lithium and/or selenium administration on magnesium, calcium and silicon levels in rats. The study was performed on rats divided into four groups (six animals each): control-received saline, Li-received Li₂CO₃ (2.7 mg Li/kg b.w.), Se-received Na₂SeO₃·H₂O (0.5 mg Se/kg b.w.), and Li+Se-received simultaneously Li₂CO₃ and Na₂SeO₃·H₂O (2.7 and 0.5 mg Se/kg b.w.). The administration was performed in form of water solutions by a stomach tube once a day for 6 weeks. In the organs (liver, kidney, brain, spleen, heart, lung and femoral muscle), the concentrations of magnesium, calcium and silicon were determined. Lithium significantly increased Ca in the kidney, brain and spleen. Coadministration of selenium reversed this effect. No changes of magnesium in organs were observed. Silicon was affected only in spleen-an increase vs. control was observed in all studied groups. The beneficial influence of coadministration of selenium in case of calcium lets us suggest that an issue of its possible use as an adjuvant alleviating side effects in lithium-treated subjects is worth being continued.

Homeostasis of chosen bioelements in organs of rats receiving lithium and/or selenium

Lithium is an essential trace element, widely used in medicine and its application is often long-term. Despite beneficial effects, its administration can lead to severe side effects including hyperparathyroidism, renal and thyroid disorders. The aim of the current study was to evaluate the influence of lithium and/or selenium treatment on magnesium, calcium and silicon levels in rats’ organs as well as the possibility of using selenium as an adjuvant in lithium therapy. The study was performed on rats divided into four groups (six animals each): control-treated with saline; Li-treated with Li₂CO₃ (2.7 mg Li/kg b.w.); Se-treated with Na₂SeO₃·H₂O (0.5 mg Se/kg b.w.); Se + Li-treated simultaneously with Li₂CO₃ and Na₂SeO₃·H₂O (2.7 mg Li/kg b.w. and of 0.5 mg Se/kg b.w., respectively). The administration was performed in form of water solutions by stomach tube once a day for 3 weeks. In the organs (liver, kidney, brain, spleen, heart, lung and femoral muscle) the concentrations of magnesium, calcium and silicon were determined. Magnesium was increased in liver of Se and Se + Li given rats. Lithium decreased tissue Ca and co-administration of selenium reversed this effect. Silicon was not affected by any treatment. The beneficial effect of selenium on disturbances of calcium homeostasis let suggest that further research on selenium application as an adjuvant in lithium therapy is worth being performed.

The interaction of adenosine and morphine on pentylenetetrazole-induced seizure threshold in mice

Adenosine agonists or low doses of morphine exert anti-convulsant effects in different models of seizures. On the other hand, a tight interaction has been reported between morphine and adenosine in various paradigms. This study investigated the effect of the interaction of adenosine and morphine on seizure susceptibility in the intravenous mouse model of pentylenetetrazole (PTZ)-induced clonic seizures. The researchers used acute systemic administration of morphine, N(6)-cyclohexyladenosine (CHA) (a selective A1 receptor agonist), naltrexone (an opioid receptor antagonist) and 8-Cyclopentyl-1,3-dimethylxanthine (8-CPT) (a selective A1 receptor antagonist). Acute administration of morphine (0.25, 0.5 and 1 mg/kg) or CHA (0.25, 0.5, 1, 2 and 4 mg/kg) raised the threshold of seizures induced by PTZ. Non-effective dose of 8-CPT (2 mg/kg) inhibited the anticonvulsant effects of CHA (0.5 and 1 mg/kg). Combination of sub-effective doses of morphine (0.125 mg/kg) and CHA (0.125 mg/kg) increased clonic seizure latency showing the additive effect of morphine and CHA. The enhanced latency induced by combination of low doses of morphine and CHA completely reversed by 8-CPT (2 mg/kg) or naltrexone (1 mg/kg). Moreover, 8-CPT (2 mg/kg) inhibited anticonvulsant effects of morphine (0.25 and 0.5 mg/kg) and naltrexone (1 mg/kg) inhibited anticonvulsant effects of CHA (0.25, 0.5 and 1 mg/kg). Combination of low doses of 8-CPT (1 mg/kg) and naltrexone (0.5 mg/kg) inhibited the anticonvulsant effect of CHA (0.5 and 1 mg/kg). In conclusion, adenosine and morphine exhibit an additive effect on the enhancement of the pentylenetetrazole-induced seizure threshold in mice, probably through A1 or μ receptors.

Endogenous opiates and behavior: 2011

This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).

The NMDA receptor complex as a therapeutic target in epilepsy: a review

A substantial amount of research has shown that N-methyl-D-aspartate receptors (NMDARs) may play a key role in the pathophysiology of several neurological diseases, including epilepsy. Animal models of epilepsy and clinical studies demonstrate that NMDAR activity and expression can be altered in association with epilepsy and particularly in some specific seizure types. NMDAR antagonists have been shown to have antiepileptic effects in both clinical and preclinical studies. There is some evidence that conventional antiepileptic drugs may also affect NMDAR function. In this review, we describe the evidence for the involvement of NMDARs in the pathophysiology of epilepsy and provide an overview of NMDAR antagonists that have been investigated in clinical trials and animal models of epilepsy.

Extending pharmacological spectrum of opioids beyond analgesia: multifunctional aspects in different pathophysiological states

Opioids are well known to exert potent central analgesic actions. In recent years, the numerous studies have unfolded the critical role of opioids in the pathophysiology of various diseases as well as in biological phenomenon of therapeutic interest. The endogenous ligands of opioid receptors are derived from three independent genes and their appropriate processing yields the major representative opioid peptides beta-endorphin, met-enkephalin, leu-enkephalin and dynorphin, respectively. These peptides and their derivatives exhibit different affinity and selectivity for the mu-, delta- and kappa-receptors located on the central and the peripheral neurons, neuroendocrine, immune, and mucosal cells and on many other organ systems. The present review article highlights the role of these peptides in central nervous system disorders such as depression, anxiety, epilepsy, and stress; gastrointestinal disorders such as diarrhea, postoperative ileus, ulceration, and irritable bowel syndrome; immune system and related inflammatory disorders such as osteoarthritis and rheumatoid arthritis; and others including respiratory, alcoholism and obesity/binge eating. Furthermore, the key role of opioids in different forms of pre- and post-conditioning including ischemic and pharmacological along with in remote preconditioning has also been described.

The NMDA receptor/nitric oxide pathway: a target for the therapeutic and toxic effects of lithium

Although lithium has largely met its initial promise as the first drug discovered in the modern era of psychopharmacology, to date no definitive mechanism for its effects has been established. It has been proposed that lithium exerts its therapeutic effects by interfering with signal transduction through G-protein-coupled receptor (GPCR) pathways or direct inhibition of specific targets in signaling systems, including inositol monophosphatase and glycogen synthase kinase-3 (GSK-3). Recently, increasing evidence has suggested that N-methyl-D-aspartate receptor (NMDAR)/nitric oxide (NO) signaling could mediate some lithium-induced responses in the brain and peripheral tissues. However, the probable role of the NMDAR/NO system in the action of lithium has not been fully elucidated. In this review, we discuss biochemical, preclinical/behavioral and physiological evidence that implicates NMDAR/NO signaling in the therapeutic effect of lithium. NMDAR/NO signaling could also explain some of side effects of lithium.