Purinergic P2Y1 Receptors Control Rapid Expression of Plasma Membrane Processes in Hippocampal Astrocytes.

Astrocytes regulate neuronal activity and blood brain barrier through tiny plasma membrane branches or astrocytic processes (APs) making contact with synapses and brain vessels. Several transmitters released by astrocytes and exerting their action on several receptor classes expressed by astrocytes themselves influence their physiology. Here we found that APs are dynamically modulated by purines. In live imaging experiments carried out in rat hippocampal astrocytes, Gq-coupled P2Y1 receptor blockade with the selective antagonist MRS2179 (1 µM) or inhibition of its effector phospholipase C using U73122 (3 µM) produced APs retraction, while stimulation of the same receptor with the selective agonist 2MeSADP (100 µM) increased their number. Since astrocytes, among other transmitters, release ATP by several mechanisms including connexin hemichannels, we used the connexin hemichannel inhibitor carbenoxolone (100 µM) and APs retraction was observed. In our system we then measured expression or function of channels important for modulation of volume transmission and K+ buffering, aquaporin-4, and K+ inward rectifying (Kir) channels, respectively. Aquaporin-4 expression level did not change whereas, in whole-cell patch-clamp recordings performed to measure Kir current, we observed an increase in K+ current in all conditions where APs number was reduced. These data are supporting the idea of a dynamic modulation of astrocytic processes by purinergic signal, strengthening the role of purines in brain homeostasis.

Circulating miR-130a, miR-27b, and miR-210 in Patients With Peripheral Artery Disease and Their Potential Relationship With Oxidative Stress.

Some emerging risk factors such as oxidative stress biomarkers and microRNAs (miRs) may add additional value to the established risk factors for peripheral artery disease (PAD). We enrolled 27 patients with PAD and 27 age-matched controls. We examined the levels of a series of miRs (miR-130a, miR-27b, and miR-210) in serum samples. The level of well-established oxidative stress biomarkers, such as lipid hydroperoxides, isoprostanes, hemeoxygenase-1 (HO-1) and reduced glutathione, was also measured in plasma and their relationship with the miRs was determined. Levels of miR-130a, miR-27b, and miR-210 were significantly increased in patients with PAD when compared to the controls. The level of miR-130 was positively correlated with body mass index, whereas miR-210 was inversely associated with pain-free walking distance (PfWD). None of the evaluated miRs was associated with lowered PfWD of patients with PAD (stage IIa > 250 m, IIb < 250 m) or oxidative stress parameters. In conclusion, our findings suggest the need for more research to assess if miRs can serve as useful markers for the early diagnosis and monitoring of PAD.