The plasma concentrations of several hormones were determined by ELISA using the following kits and according to the manufacturer’s protocols: rat intact PTH (Immunotopics, cat. 60-2500), FGF-23 (Kainos Laboratories, CY-4000), Rat Klotho KLOT (BlueGene, E02K0027), secreted frizzled-related protein 4 (SFRP4; Biomatik, EKU07221), matrix extracellular phosphoglycoprotein (MEPE; Cloud-Clone Corp., SEB232Ra), dopamine (Cloud-Clone Corp, CEA851Ge), rat CORT for corticosterone (Elabscience, EL-0160), rat thyroxine (T4) ELISA Kit (Cusabio, E05082r), General Calcitriol ELISA Kit (EIAab, E0467Ge), and Insulin kit (Could-Clone Corp, CEA448Ra).
Total nicotinamide adenine dinucleotide was determined with an NAD+/NADH Assay Kit (Abcam, ab65348) in 20 mg of kidney cortex and jejunum scrapings, following the kit’s procedure. Optical density was determined at 450 nm with a DTX 880 Multimode Detector (Beckman Coulter).