Targeting Na,K-ATPase-Src signaling to normalize cerebral blood flow in a murine model of familial hemiplegic migraine

Abstract

Familial hemiplegic migraine type 2 (FHM2) is linked to Na,K-ATPase α₂ isoform mutations, including that of G301R. Mice heterozygous for this mutation (${\alpha }_2^{+/\text{G3}0\text{1R}}$) show cerebrovascular hypercontractility associated with amplified Src kinase signaling, and exaggerated neurovascular coupling. This study hypothesized that targeting Na,K-ATPase-dependent Src phosphorylation with pNaKtide would normalize cerebral perfusion and neurovascular coupling in ${\alpha }_2^{+/\text{G3}0\text{1R}}$ mice. The effect of pNaKtide on cerebral blood flow and neurovascular coupling was assessed using laser speckle contrast imaging in awake, head-fixed mice with cranial windows in a longitudinal study design. At baseline, compared to wild type, ${\alpha }_2^{+/\text{G3}0\text{1R}}$ mice exhibited increased middle cerebral artery tone; with whisker stimulation leading to an exaggerated increase in sensory cortex blood flow. No difference between genotypes in telemetrically assessed blood pressure occurred. The exaggerated neurovascular coupling in ${\alpha }_2^{+/\text{G3}0\text{1R}}$ mice was associated with increased K_ir2.1 channel expression in cerebrovascular endothelium. Two weeks pNaKtide treatment normalized cerebral artery tone, endothelial K_ir2.1 expression, and neurovascular coupling in ${\alpha }_2^{+/\text{G3}0\text{1R}}$ mice. Inhibition of the Na,K-ATPase-dependent Src kinase signaling with pNaKtide prevented excessive vasoconstriction and disturbances in neurovascular coupling in ${\alpha }_2^{+/\text{G3}0\text{1R}}$ mice. pNaKtide had only minor hypotensive effect similar in both genotypes. These results demonstrate a novel treatment target to normalize cerebral perfusion in FHM2.

Keywords: Cerebral hypoperfusion; Src kinase; migraine; neurovascular coupling; sodium-potassium pump.