The purposes of this study were to use vocalization and posture as indices of the neuromuscular pathology that develops in zinc-deficient guinea pigs and to determine the rate of depletion before and of repletion after intraperitoneal (IP) zinc therapy. When severe signs of deficiency developed, tissues were analyzed for their zinc content to assess sites of depletable and mobilizable zinc stores. Weanling guinea pigs were fed low (less than 1 mg/kg) and adequate (100 mg/kg) zinc diets based on isolated soybean protein or autoclaved egg white. The first signs (stage 1) of vocalization due to handling, abnormal posture and skin lesions developed after approximately 4 wk. Severe (stage 3) signs followed after 5-6 wk. A single IP dose of ZnSO4 (50 mumol/kg) caused remission of signs within 4-5 d following which all signs regressed to stage 3 within 7 d. Analysis of 15 tissues from severely deficient guinea pigs showed that only plasma and bone had significantly lower zinc concentrations than tissues from comparable age-related controls fed a zinc-adequate diet. It seems unlikely that major soft tissues, such as muscle, brain, liver and skin, serve as mobilizable stores of zinc for other critical metabolic functions. Bone zinc is slowly mobilized but at a rate insufficient to maintain health or even life.
Animals Diet