Parathyroid hormone fragment 1-34 and anti-inflammatory effect

We have studied the possible activity of the rat parathyroid hormone fragment 1-34, peripherally or centrally injected, on the vascular permeability induced by local administration of croton oil. Our study considered also the possible interference of parathyroid hormone fragment 1-34 on the release of histamine by mast cells and on the content of histamine in paw tissue. Parathyroid hormone fragment 1-34 significantly reduced the increase in vascular permeability produced in mice by local croton oil injection, as well as the serotonin-induced paw edema in the rat. These effects of parathyroid hormone fragment 1-34 were present only after peripheral administration. At the dose of 3.3 micrograms/kg, it decreased the histamine content in paw tissue. Peripheral administration of a calcium antagonist, such as nimodipine, at the dose of 50 micrograms/kg, or a metal-chelating agent, such as ethylene-diaminetetraacetic acid, at the dose of 10 micrograms/kg, antagonized the anti-inflammatory effect of parathyroid hormone fragment 1-34. Moreover, at 10-100 microliters/ml it significantly decreased the histamine release by mast cells.