Effects Of Endogenous Parathyroid Hormone On The Structure And Function Of Parotid Gland In Mice

Parathyroid hormone is synthetized and secreted by chief cells of the parathyroid glands,as one of the most important endocrine regulators of calcium and phosphorus concentration and metabolism in extracellular fluid. Recent studies have shown that, PTH has a role in both bone formation and bone resorption,suggesting its importance in the process of bone remodeling and restoration. Parathyroid hormone related protein is a HHM-inducing peptide. It exhibits certain structural similarity to PTH and the two hormones may act through the same receptors. PTHrP is known to be produced in various tissues, such as kidney, pancreatic gland, hypothalamus, et al. PTHrP also has a critical role in branching morphogenesis of the mammary gland. Had a report showen that, administration of bovine PTH preparations increased the phosphate concentration in the parotid saliva of sheep. In the skin, PTHrP expression was demonstrated in epidermis and in smooth muscle cell layer of blood vessels. And in parotid glands, the PTHrP was localised in excretory ducts and in blood vessels. Parotid glands is the one of three major salivary glands in human being, and it's extremely important for the function of the oral cavity. In the current study, two-step experiments were performed to clarify the effects of endogenous parathyroid hormone on the structure and function of parotid gland in PTH-null mice and to explore the molecular mechanisms of the effect of PTH for parotid gland. PartⅠEffects of endogenous parathyroid hormone on the structure of parotid gland in miceObjective: To investigate the effects of endogenous parathyroid hormone (PTH) on the structure of parotid gland in mice.Methods: 10 PTH gene knockout mice (PTH-/-) and 10 wild mice (PTH+/+), the differences between the two groups were assessed by weighing and histology method.Results: Compared with the wild mice, the weights of parotid glands ratio the body weight were significantly decreased about 30%( t=5.497,P<0.01), and the acinar quantity decreased and the form was asymmetry in mice with PTH-/-. Additionally, the the ductus system was comparatively developed in mice with PTH-/-.Conclusion: Endogenous parathyroid hormone has important effect on the structure of parotid gland in mice.PartⅡ: Effects of endogenous parathyroid hormone on the function of parotid gland in miceObjective: To investigate the effects of endogenous parathyroid hormone (PTH) on the function of parotid gland in mice.Methods: 10 PTH gene knockout mice (PTH-/-) and 10 wild mice (PTH+/+), the state salivary flow rate was measured by intramuscular injection of pilocarpine nitrate after anaesthesia. Taking the salivary, and measured the contents of calcium and by spectrophotometer. Results: Compared with the wild mice, the state salivary flow rate was significantly decreased in mice with PTH-/-( P<0.01). Additionally, the contents of calcium was lower, and the contents of phosphorus was higher in mice with PTH-/-.Conclusion: Endogenous parathyroid hormone has important effect on the function of parotid gland in mice.