Black bear parathyroid hormone (PTH) and functional fragments thereof are provided. Also provided are methods of using black bear PTH and functional fragments for increasing cAMP in a bone-forming cell； reducing apoptosis in a bone-forming cell； decreasing the ratio of expression levels of Bax protein to Bcl-2 protein in a bone-forming cell； increasing the expression level of one or more of a bone matrix protein, a transcriptional activator, or a transcriptional regulator in a bone-forming cell； enhancing bone mineral density, increasing bone mass, decreasing bone loss, or reducing the incidence of bone fractures, or any combination thereof, in a subject； also provided are antibodies directed against black bear parathyroid hormone (PTH) and functional fragments thereof.
