After the assessment of EPSC frequency, the cells were held in current-clamp mode while current steps were presented to the neurons in order to characterize the neurons based on firing properties,

as described in Grudt and Perl (2002). Neurons that showed a delayed discharge of action potentials after the current step were characterized as delayed. Neurons that fired one or a few action potentials only were characterized as transient. Neurons that regularly fired action potentials throughout the duration of the current step were characterized as tonic. Neurons that did not fire action potentials, fired irregular patterns of action potentials, or were lost before switching to current clamp were classified as other. We thank JrGang Cheng at the University of North Carolina BAC Core for generating the CGRPα targeting arms, Megumi Aita for performing in situ hybridization, Fan Wang at Duke University for providing Advillin-Cre mice, Edward Dinaciclib Perl for allowing us to use his skin-nerve electrophysiology rig, Sarah Shoemaker for mouse

colony management, Brendan Fitzpatrick for performing surgeries, Kenji Kohno for providing hDTR (pTRECK1) plasmid, and Masatoshi Takeichi for providing TRPM8 antibody. This work was supported by grants to M.J.Z. from The Searle Scholars Program, The Klingenstein Foundation, The Rita Allen Foundation, and NINDS (R01NS060725, R01NS067688). The BAC Core, Confocal Imaging Core, and In Situ Hybridization Core are funded by grants from NINDS VX770 (P30NS045892) science and NICHD (P30HD03110). “
“Vitamin D insufficiency is associated with chronic kidney disease (CKD) and gives rise to secondary hyperparathyroidism (SHPT) which can lead to loss of bone density and elevated rates of fracture in renal patients [1]. Vitamin D therapies are therefore widely used in the management

of chronic kidney disease (CKD). Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) supplementation is the standard of care for correcting vitamin D insufficiency in CKD [2], while vitamin D hormones (calcitriol and other synthetic hormones) are used to control SHPT [3]. Both of these therapeutic approaches have significant limitations. Vitamins D2 and D3 (collectively “vitamin D”) are absorbed less readily than more polar vitamin D compounds [4], and the degree of absorption can vary considerably between patients [5]. Once absorbed, vitamin D must undergo two sequential hydroxylations to be active: first at carbon 25 by CYP2R1 or CYP27A1 to form 25-hydroxyvitamin D, and then at carbon 1 by CYP27B1 to form 1,25-dihydroxyvitamin D [6]. Hepatic 25-hydroxylation varies widely in efficiency and, together with variable absorption, complicates the determination of optimal dose [7] and [8]. Significant percentages of CKD patients receiving vitamin D supplements do not attain targeted levels of serum 25-hydroxyvitamin D [9] and [10].