Lithium ions in nanomolar concentration modulate glycine-activated chloride current in rat hippocampal neurons

Antiviral Drug Ivermectin at Nanomolar Concentrations Inhibits Glycine-Induced Chloride Current in Rat Hippocampal Neurons

Ivermectin (IVM) belongs to the class of macrocyclic lactones, which is used as an antiparasitic agent. At present, the researchers focus on possibility to use IVM in treatment of certain forms of cancer and viral diseases such as COVID-19. The mechanisms of IVM action are not clear. It is assumed that IVM affects chloride channels and increases cytoplasmic concentration of chloride. This study examines the effect of IVM on chloride currents induced by glycine (I_Gly). Experiments were carried out on isolated pyramidal neurons of the rat hippocampus with whole-cell patch clamp. A short-term (600 msec) application of IVM in a concentration of 10 μM induced a slow inward current, which persisted after washing the neurons. The low concentrations (0.1-1000 nM) of IVM did not induce any novel current, but it rapidly and reversibly reduced the peak amplitude and accelerated desensitization of I_Gly in a dose-dependent manner. The threshold concentrations of IVM sufficient to reduce peak amplitude of I_Gly and to accelerate desensitization of I_Gly were 100 nM and 0.1 nM, respectively. The study revealed a high sensitivity of neuronal glycine receptors to IVM.

Effect of a New Lithium Preparation on the Behavior of CBA/CaLac Mice in an Experimental Conflict Model

The use of lithium drugs in clinical practice requires constant monitoring of lithium plasma concentration, because toxicity is sometimes observed at therapeutic concentrations of lithium. This is often associated with fluctuations of plasma concentration of lithium ions after intake of individual doses. Therefore, the use of a porous carrier providing a stable blood level of the drug is extremely promising and important for clinical practice. We studied activity of a new lithium drug (lithium complex) consisting of aluminum-silicon base and lithium citrate immobilized on its surface. Lithium carbonate served as the reference drug. It was shown that lithium carbonate and lithium complex exhibited no anxiolytic activity in the conflict model, but produced an antidepressant effect and improved exploratory behavior of animals.

Modulation of GABA and glycine receptors in rat pyramidal hippocampal neurones by 3α5β-pregnanolone derivatives

The ability of pregnanolone glutamate (PA-Glu), pregnanolone hemisuccinate (PA-hSuc) and pregnanolone hemipimelate (PA-hPim), neuroactive steroids with a negative modulatory effect on excitatory N-methyl-d-aspartate receptors, to influence the functional activity of inhibitory γ-aminobutyric acid and glycine receptors was estimated. The GABA- and glycine-induced chloride currents (I_GABA and I_Gly) were measured in isolated pyramidal neurons of the rat hippocampus using the patch-clamp technique. Compound PA-Glu was found to potentiate I_GABA and to inhibit I_Gly, while PA-hSuc and PA-hPim inhibited both I_GABA and I_Gly. Moreover, PA-Glu, PA-hSuc, and PA-hPim had a greater effect on desensitization than on the peak amplitude of I_Gly. At a high concentration of glycine (500 μM), the effect of neurosteroids on the peak amplitude of I_Gly disappeared, and the acceleration of desensitization remained. The conversion of PA-Glu into androstane glutamate (AND-Glu), an analogue that lacks the C-17 acetyl moiety, completely eliminated the effects on these receptors. Our results indicate that the C-17 acetyl moiety is crucial for the action on I_GABA and I_Gly. Our results indicate that the pregnanolone derivatives, in contrast to the androstane analogues, modulate I_GABA and I_Gly at low micromolar concentrations and this family of neurosteroids can be useful for future structure-activity relationship studies of the steroid modulation of other receptor types.

Long-term lithium treatment increases intracellular and extracellular brain-derived neurotrophic factor (BDNF) in cortical and hippocampal neurons at subtherapeutic concentrations

OBJECTIVES

The putative neuroprotective effects of lithium treatment rely on the fact that it modulates several homeostatic mechanisms involved in the neurotrophic response, autophagy, oxidative stress, inflammation, and mitochondrial function. Lithium is a well-established therapeutic option for the acute and long-term management of bipolar disorder and major depression. The aim of this study was to evaluate the effects of subtherapeutic and therapeutic concentrations of chronic lithium treatment on brain-derived neurotrophic factor (BDNF) synthesis and secretion.

METHODS

Primary cultures of cortical and hippocampal neurons were treated with different subtherapeutic (0.02 and 0.2 mM) and therapeutic (2 mM) concentrations of chronic lithium treatment in cortical and hippocampal cell culture.

RESULTS

Lithium treatment increased the intracellular protein expression of cortical neurons (10% at 0.02 mM) and hippocampal neurons (28% and 14% at 0.02 mM and 0.2 mM, respectively). Extracellular BDNF of cortical neurons increased 30% and 428% at 0.02 and 0.2 mM, respectively and in hippocampal neurons increased 44% at 0.02 mM.

CONCLUSION

The present study indicates that chronic, low-dose lithium treatment up-regulates BDNF production in primary neuronal cell culture.