Adenosine receptors mainly control synaptic function, and excessive activation of adenosine receptors may worsen the onset of many neurological disorders. Accordingly, the regular intake of moderate doses of caffeine antagonizes adenosine receptors and affords robust neuroprotection. Although caffeine intake alters brain functional connectivity and multi-omics analyses indicate that caffeine intake modifies synaptic and metabolic processes, it is unclear how caffeine intake affects behavior, synaptic plasticity and its modulation by adenosine. We now report that male mice drinking caffeinated water (0.3 g/L) for 2 weeks were behaviorally indistinguishable (locomotion, mood, memory) from control mice (drinking water) and displayed superimposable synaptic plasticity (long-term potentiation) in different brain areas (hippocampus, prefrontal cortex, amygdala). Moreover, there was a general preservation of the efficiency of adenosine A₁ and A_2A receptors to control synaptic transmission and plasticity, although there was a tendency for lower levels of endogenous adenosine ensuring A₁ receptor-mediated inhibition. In spite of similar behavioral and neurophysiological function, caffeine intake increased the energy charge and redox state of cortical synaptosomes. This increased metabolic competence likely involved a putative increase in the glycolytic rate in synapses and a prospective greater astrocyte–synapse lactate shuttling. It was concluded that caffeine intake does not trigger evident alterations of behavior or of synaptic plasticity but increases the metabolic competence of synapses, which might be related with the previously described better ability of animals consuming caffeine to cope with deleterious stimuli triggering brain dysfunction.

Fear learning is essential to survival, but traumatic events may lead to abnormal fear consolidation and overgeneralization, triggering fear responses in safe environments, as occurs in post-traumatic stress disorder (PTSD). Adenosine A_2A receptors (A_2AR) control emotional memory and fear conditioning, but it is not known if they affect the consolidation and generalization of fear, which was now investigated. We now report that A_2AR blockade through systemic administration of the A_2AR antagonist SCH58261 immediately after contextual fear conditioning (within the consolidation window), accelerated fear generalization. Conversely, A_2AR activation with CGS21680 decreased fear generalization. Ex vivo electrophysiological recordings of field excitatory post-synaptic potentials (fEPSPs) in CA3-CA1 synapses and of population spikes in the lateral amygdala (LA), showed that the effect of SCH58261 is associated with a reversion of fear conditioning-induced decrease of long-term potentiation (LTP) in the dorsal hippocampus (DH) and with increased amplitude of LA LTP in conditioned animals. These data suggest that A_2AR are engaged during contextual fear consolidation, controlling long-term potentiation mechanisms in both DH and LA during fear consolidation, impacting on fear generalization; this supports targeting A_2AR during fear consolidation to control aberrant fear processing in PTSD and other fear-related disorders.

De novo variants in KCNQ2 cause neonatal onset developmental and epileptic encephalopathy ( KCNQ2 ‐DEE; Online Mendelian Inheritance in Man #613720), most often by loss‐of‐function in vitro effects. In this study, we describe a neonatal onset DEE proband carrying a recurrent de novo KCNQ2 variant (c.794C>T; p.A265V) affecting the pore domain of KCNQ2 ‐encoded Kv7.2 subunits. Whole‐cell patch‐clamp measurement in a mammalian heterologous expression system revealed that, when compared to wild‐type Kv7.2 channels, channels containing Kv7.2 A265V subunits displayed (1) reduced maximal current density; (2) decreased voltage‐dependence of activation; and (3) an unusual inactivation process, with a 50% current reduction during 1–2‐s depolarizing pulses at voltages > 0 mV. These effects were proportional to the number of mutant subunits incorporated in heteromeric channels, being overall less dramatic upon coexpression with Kv7.2 or Kv7.2 + Kv7.3 subunits. These results reveal current inactivation as a novel pathogenetic mechanism for KCNQ2 ‐DEE caused by a recurrent variant affecting a critical pore residue, further highlighting the importance of in vitro functional assessment for a better understanding of disease molecular pathophysiology.

Neuropathic pain (NP) is a debilitating condition manifesting with cold and mechanical allodynia and/or hyperalgesia often developing during treatment with anticancer drugs (chemotherapy-induced NP, CINP). Activation of neuronal Kv7 voltage-gated potassium channels with flupirtine (FLU) or retigabine (RET) increases pain threshold in several human and rodent NP conditions. Unfortunately, both FLU and RET have been withdrawn from the market, and no Kv7 activator is currently available for clinical use. In this study, the potential pain-relieving effects exerted by acute and chronic treatment with a novel RET analogue (C60) with improved pharmacological properties over the parent compound were assessed in an oxaliplatin (OXA)-induced NP model in mice. Acute treatment with RET or C60 (0.1-3 mg/Kg) dose-dependently reduced cold and mechanical hypersensitivity in mice treated with OXA; the Kv7 blocker XE-991 fully reversed these effects. Chronic treatment with RET or C60 (1 mg/Kg) prevented the development of OXA-induced cold allodynia and mechanical hyperalgesia. In selected stations of the pain pathway, OXA reduced the expression of Kv7.2, Kv7.3 and Kv7.5 subunits, also causing neuronal loss and astrogliosis. Chronic treatment with Kv7 openers prevented OXA-induced decrease in Kv7.5 expression in the spinal cord (C60 only) and in the cortex (both RET and C60), and abolished astrogliosis in the PAG (RET and C60) and the spinal cord (C60). These results demonstrate that Kv7 activation, in addition to relieving acute pain, prevented CINP development, highlighting the modulation of Kv7 subunit expression (Kv7.5 in particular) in pain-related structures as potential molecular underpinnings for such preventative effects.

Neuropathic pain (NP) is a debilitating condition manifesting with cold and mechanical allodynia and/or hyperalgesia often developing during treatment with anticancer drugs (chemotherapy-induced NP, CINP). Activation of neuronal Kv7 voltage-gated potassium channels with flupirtine (FLU) or retigabine (RET) increases pain threshold in several human and rodent NP conditions. Unfortunately, both FLU and RET have been withdrawn from the market, and no Kv7 activator is currently available for clinical use. In this study, the potential pain-relieving effects exerted by acute and chronic treatment with a novel RET analogue (C60) with improved pharmacological properties over the parent compound were assessed in an oxaliplatin (OXA)-induced NP model in mice. Acute treatment with RET or C60 (0.1-3 mg/Kg) dose-dependently reduced cold and mechanical hypersensitivity in mice treated with OXA; the Kv7 blocker XE-991 fully reversed these effects. Chronic treatment with RET or C60 (1 mg/Kg) prevented the development of OXA-induced cold allodynia and mechanical hyperalgesia. In selected stations of the pain pathway, OXA reduced the expression of Kv7.2, Kv7.3 and Kv7.5 subunits, also causing neuronal loss and astrogliosis. Chronic treatment with Kv7 openers prevented OXA-induced decrease in Kv7.5 expression in the spinal cord (C60 only) and in the cortex (both RET and C60), and abolished astrogliosis in the PAG (RET and C60) and the spinal cord (C60). These results demonstrate that Kv7 activation, in addition to relieving acute pain, prevented CINP development, highlighting the modulation of Kv7 subunit expression (Kv7.5 in particular) in pain-related structures as potential molecular underpinnings for such preventative effects.