Oxytocin’s capacity to affect the glial cell functions is increasingly recognized. We previously reported that oxytocin could cause both excitation and inhibition of Ca²⁺ signals and glutamate release in the processes of adult rodent astrocytes. Our purpose here was to investigate oxytocin receptor expression and oxytocin effects in astrocytes. In primary cortical astrocytes, we assessed the presence of oxytocin receptors by confocal imaging, and the effects of oxytocin receptor activation on intracellular Ca²⁺ signals and glutamate release. We found that oxytocin receptors are expressed in both the soma and processes of astrocytes; oxytocin at nanomolar concentrations could induce dual responses in astrocytes, namely facilitation and inhibition of Ca²⁺ signals and glutamate release; the oxytocin facilitatory and inhibitory effects were duplicated by the biased agonists carbetocin and atosiban, respectively; and the facilitatory and the inhibitory effect were dependent on activation of a G_q and a G_i pathway, respectively. It is concluded that oxytocin effects in astrocytes could duplicate the effects in processes prepared from astrocytes matured in neuron-astrocyte networks, substantiating the use of astrocytes to study astrocytic oxytocin molecular signaling.

Chronic inflammation is a major driver of lung damage in cystic fibrosis (CF), yet the molecular mechanisms that sustain this self-reinforcing inflammatory state remain incompletely understood. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in NAD biosynthesis, can also act extracellularly (eNAMPT) as a pro-inflammatory mediator. Here, we investigated the relationship between NAMPT and matrix metalloproteinase-9 (MMP-9) in CF. Peripheral blood mononuclear cells (PBMCs) from people with CF (pwCF) displayed increased intracellular NAMPT and MMP-9 expression, together with enhanced AKT and ERK1/2 phosphorylation, compared with non-CF controls. Circulating eNAMPT levels were elevated in pwCF and positively correlated with MMP-9 levels. Although baseline eNAMPT levels were not significantly associated with FEV1% predicted, in a small longitudinal cohort, eNAMPT decreased following one year of elexacaftor/tezacaftor/ivacaftor (ETI) treatment, while FEV1% predicted increased in six of seven patients with paired measurements. In vitro, recombinant NAMPT increased MMP-9 expression and enzymatic activity in PBMCs from healthy donors. Pharmacological treatment with FK866 reduced endogenous eNAMPT release and attenuated NAMPT-induced MMP-9 production. Mechanistically, eNAMPT triggered rapid AKT activation followed by sustained ERK1/2 phosphorylation. Pharmacological inhibition of the MEK/ERK pathway attenuated NAMPT-induced MMP-9 activity, supporting a functional contribution of ERK1/2 signaling to NAMPT-mediated MMP-9 activation. Together, these findings identify a functional NAMPT–MMP-9 axis associated with inflammatory signaling in CF. Further studies are needed to establish its contribution to pulmonary inflammation and to determine the clinical significance of circulating eNAMPT in larger patient cohorts.