CKD-associated cachexia model.

Two-stage 5/6 nephrectomy surgery was performed in SD rats for a CKD-associated cachexia model, and sham controls experienced the same procedures without excision of kidney tissue, as described previously (33). Briefly, for the stage I surgery (Neph-I), the animals were anesthetized with isoflurane and placed prone in a clean environment. A 1 cm posterior incision was made on the left flank through which the left kidney was located. For animals undergoing nephrectomy, the renal capsule was removed, the upper and lower one-third of the kidney was transected, and the resultant wound was cauterized, leaving the middle one-third of the kidney with renal artery and vein intact. For control animals receiving a sham operation, the renal capsule was opened up to simulate the manipulations performed in the nephrectomy. The surgical wounds were then closed via suture at the muscle and skin layers. Animals that received surgery were allowed to recover and individually housed. Seven days after stage I surgery, animals were again anesthetized and placed prone in the surgical area for the stage II surgery (Neph-II). This time, a right 1 cm incision was performed and the right kidney was isolated. For animals undergoing nephrectomy, the renal capsule was removed and vasculature was tied off with suture. The vascular bundle was then transected distal to the suture, and the entire kidney was removed. For animals in the sham-treatment group, the renal capsule was removed. The surgical wounds were closed with suture at the muscle and skin layers. A dose of analgesic was administered after each stage of surgery (buprenorphine, 0.05 mg/kg, s.c.).