Osteopontin and mucosal protection.

Protection of mucosal tissues of the oral cavity, intestines, respiratory tract, and urogenital tract from the constant challenge of pathogens is achieved by the combined barrier function of the lining epithelia and specialized immune cells. Recent studies have indicated that osteopontin (OPN) has a pivotal role in the development of immune responses and in the tissue destruction and the subsequent repair processes associated with inflammatory diseases. While expression of OPN is increased in immune cells--including neutrophils, macrophages, T- and B-lymphocytes--and in epithelial, endothelial, and fibroblastic cells of inflamed tissues, deciphering the specific functions of OPN has been difficult. In part, this is due to the broad range of biological activities of OPN that are mediated by multiple receptors which recognize several signaling motifs whose activities are influenced by post-translational modifications and proteolytic processing of OPN. Understanding the role of OPN in mucosal inflammation is further complicated by its contributions to the barrier function of the lining epithelia and the complexity of the specialized mucosal immune system. In an attempt to provide some insights into the involvement of OPN in mucosal diseases, this review summarizes current knowledge of the biological activities of OPN involved in the development of inflammatory responses and in wound healing, and indicates how these activities may affect the protection of mucosal tissues.

Microinjection of D-2-amino-7-phosphonoheptanoate into the dorsal periaqueductal gray matter reduces the pressor response to glutamate injected at the same site.

The current study assesses the influence of the N-methyl-D-aspartate (NMDA) receptor antagonist D-2-amino-7-phosphonoheptanoate (AP7) on the pressor effect of glutamate microinjected into the dorsal periaqueductal gray matter (DPAG) of urethane-anesthetized rats. Glutamate (20, 40 and 80 nmol/site) caused dose-related reproducible increases in systolic and diastolic blood pressure. Microinjection of saline into the DPAG did not alter the pressor effects of glutamate (80 nmol/site). Similar pretreatment with AP7 (2 nmol/site) significantly (P less than 0.05) attenuated the pressor effects of glutamate from +26.5 +/- 7.0 to +3.4 +/- 3.3 mmHg (systolic blood pressure). We conclude that the pressor effect of glutamate in the DPAG is mediated largely by activation of NMDA receptors.