Anti-inflammatory cytokines are known to exert neuroprotective action ameliorating aberrant neuronal network activity associated with inflammatory responses. Yet, it is still not fully understood if anti-inflammatory cytokines play a significant role in the regulation of synaptic activity under normal conditions. Thus, the aim of our study was to investigate the effect of Interleukin-10 (IL-10) on neuronal synaptic transmission and plasticity. For this we tested the effect of IL-10 on miniature excitatory postsynaptic currents (mEPSC) and intracellular Ca²⁺ responses using whole-cell patch clamp and fluorescence microscopy in 13–15 DIV primary hippocampal neuroglial culture. We found that IL-10 significantly potentiated basal glutamatergic excitatory synaptic transmission within 15 min after application. Obtained results revealed a presynaptic nature of the effect, as IL-10 in a dose-dependent manner significantly increased the frequency but not the amplitude of mEPSC. Further, we tested the effect of IL-10 on mEPSC in a model of homeostatic synaptic plasticity (HSP) induced by treatment of primary hippocampal culture with 1 µM of tetrodotoxin (TTX) for a 24 h. It was found that 15 min application of IL-10 at established HSP resulted in enhanced mEPSC frequency, thus partially compensating for a decrease in the mEPSC frequency associated with TTX-induced HSP. Next, we studied if IL-10 can influence induction of HSP. We found that co-incubation of IL-10 with 1 µM of TTX for 24 h induced synaptic scaling, significantly increasing the amplitude of mEPSC and Ca²⁺ responses to application of the AMPA agonist, 5-Fluorowillardiine, thus facilitating a compensatory postsynaptic mechanism at HSP condition. Our results indicate that IL-10 potentiates synaptic activity in a dose- and time-dependent manner exerting both presynaptic (short-term exposure) and postsynaptic (long-term exposure) action. Obtained results demonstrate involvement of IL-10 in the regulation of basal glutamatergic synaptic transmission and plasticity at normal conditions.

Various models, including stem cells derived and isolated cardiomyocytes with overexpressed channels, are utilized to analyze the functional interplay of diverse ion currents involved in cardiac automaticity and excitation–contraction coupling control. Here, we used β-NAD and ammonia, known hyperpolarizing and depolarizing agents, respectively, and applied inhibitory analysis to reveal the interplay of several ion channels implicated in rat papillary muscle contractility control. We demonstrated that: 4 mM β-NAD, having no strong impact on resting membrane potential (RMP) and action potential duration (APD90) of ventricular cardiomyocytes, evoked significant suppression of isometric force (F) of paced papillary muscle. Reactive blue 2 restored F to control values, suggesting the involvement of P2Y-receptor-dependent signaling in β-NAD effects. Meantime, 5 mM NH₄Cl did not show any effect on F of papillary muscle but resulted in significant RMP depolarization, APD90 shortening, and a rightward shift of I–V relationship for total steady state currents in cardiomyocytes. Paradoxically, NH₄Cl, being added after β-NAD and having no effect on RMP, APD, and I–V curve, recovered F to the control values, indicating β-NAD/ammonia antagonism. Blocking of HCN, Kir2.x, and L-type calcium channels, Ca²⁺-activated K⁺ channels (SK, IK, and BK), or NCX exchanger reverse mode prevented this effect, indicating consistent cooperation of all currents mediated by these channels and NCX. We suggest that the activation of Kir2.x and HCN channels by extracellular K⁺, that creates positive and negative feedback, and known ammonia and K⁺ resemblance, may provide conditions required for the activation of all the chain of channels involved in the interplay. Here, we present a mechanistic model describing an interplay of channels and second messengers, which may explain discovered antagonism of β-NAD and ammonia on rat papillary muscle contractile activity.

Glutamate excitotoxicity, a hallmark of acute brain injury, causes intracellular calcium overload and disrupts cation homeostasis. Although selective neuronal vulnerability is well established, the coordinated multi-ion mechanisms underlying resistance or death in distinct subpopulations, and the role of neuron–glia interactions, remain poorly understood. Using synchronous multi-channel fluorescence imaging in primary hippocampal cultures, we assessed coupled dynamics of cytosolic [Ca²⁺]i, [Na⁺]i, [K⁺]i, and pHᵢ in neurons and astrocytes exposed to toxic glutamate concentration (100 μM). Based on post-washout [Ca²⁺]ᵢ recovery, neurons were divided into fast-return, slow-return, and no-return groups. Vulnerable no-return neurons showed irreversible Ca²⁺ overload and persistent K⁺ loss, and contained the highest proportion of cells expressing calcium-permeable AMPA receptors and GluK1-containing kainate receptors. GABAergic neurons were mainly found in the slow-return and no-return groups. Fast-return neurons exhibited a two-step [Na⁺]i rise during glutamate application and washout, coinciding with a sharp [Ca²⁺]i decline, and marked cytosolic acidification; however, pHᵢ and [Na⁺]i did not recover even 40 min after washout. Their [K⁺]i recovered almost immediately and correlated inversely with [Ca²⁺]i, while [Na⁺]i correlated inversely with pHᵢ. Astrocytes rapidly cleared Ca²⁺ and stabilized pH despite sustained Na⁺ accumulation; their [K⁺]i also recovered quickly and correlated inversely with [Ca²⁺]i. GABABR agonist baclofen shifted neurons toward the slow-return group, whereas the A₁ adenosine agonist N⁶-cyclohexyladenosine abolished irreversible calcium collapse and expanded the fast-return pool. These findings clarify mechanisms of selective neuronal resilience to excitotoxicity and support Gᵢ-receptor activation as a strategy to preserve ion homeostasis.