Zinc Deficiency Increases Serum Concentrations of Parathyroid Hormone through a Decrease in Serum Calcium and Induces Bone Fragility in Rats

Abstract

SummaryWe hypothesized that a zinc-deficient diet alters the mineral (calcium, magnesium, and phosphorus) components of bones, as well as hormones related to bone remodeling, and negatively affects bone metabolism. Four-week-old male Wistar rats were randomly assigned to one of three groups for 4 wk: a zinc-adequate group (C, 30 ppm); a zinc-deficient group (ZD, 1 ppm); and a pair-fed group (PF, 30 ppm), which was pair-fed to the ZD group. Bone mineral density and bone mechanical properties were reduced in the ZD group compared to the C and PF groups. Compared with the C and PF groups, serum osteocalcin, a bone formation marker, was reduced in the ZD group. Conversely, urine deoxypyridinoline, a bone resorption marker, was increased in the ZD group compared to the C and PF groups. Calcium and phosphorus concentrations in bone were not different among all groups. The bone magnesium concentration was significantly higher in the ZD group than in the PF and C groups. Interestingly, compared with the C and PF groups, the ZD group showed a reduction in serum calcium concentration along with an increase in serum parathyroid hormone (PTH) concentration. Although serum 1,25-dihydroxycholecalciferol concentration was significantly higher in the ZD and PF groups than in the C group, the rate of apparent calcium absorption was significantly lower in the ZD group than in the C and PF groups. Therefore, zinc deficiency is suspected to cause an increase in serum PTH concentration owing to an inability to maintain calcium homeostasis, resulting in bone fragility.

A short-term zinc-deficient diet decreases bone formation through down-regulated BMP2 in rat bone

“…2,3) Furthermore, we previously observed that long-term (4 weeks) zinc deficiency decreases bone formation and increases bone resorption, resulting in bone loss. 4) Although several studies have proved that zinc deficiency leads to the development of osteoporosis 5,6) , few studies have attempted to examine the effect of short-term dietary zinc deficiency on bone metabolism.…”

“…The experimental diets were prepared as described in a previous study. 4) After 1 week of treatment, the rats were fasted for 12 h, were then anesthetically sacrificed for dissection, and blood and femur samples were collected for analysis. These studies were approved by the Animal Studies Committee of Tokyo University of Agriculture, and all procedures involving rats were conducted in accordance with the guidelines for the Care and Use of Laboratory Animals of Tokyo University of Agriculture.…”

“…Serum zinc and calcium were measured as described previously. 4) The serum levels of osteocalcin and the C-terminal telopeptide of type I collagen (CTx) were measured as described previously. 8) Extraction of total RNA and synthesis of complementary DNA were performed as described previously.…”

Zinc deficiency decreases bone mineral density of rat by calmodulin-induced change in calcium metabolism

“…The skeleton is a reserve of calcium which is drawn upon to maintain adequate serum calcium when calcium intake is limited. Elevated PTH stimulates bone resorption and release of bone calcium for restoring serum calcium concentration, a process that ultimately causes a decrease in BMD [29] (Figure 5). If LZG had continued to be fed a low zinc diet, the calcium deficiency of rat would have been more severe.…”

Role of calcium and vitamin D in prevention and treatment of osteoporosis

“…Цинк служит коферментом для многих металлоферментов и участвует в регуляции активности остеобластов, синтеза коллагена и активности щелочной фосфатазы. Дефицит цинка может сопровождаться снижением всасывания кальция в кишечнике и повышением уровня паратгормона, который активирует костный обмен [46]. В одном исследовании средние сывороточные концентрации цинка у женщин с остеопорозом были значительно ниже, чем у женщин с остеопенией или здоровых женщин [47].…”