Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
Short-term studies have shown that histamine is involved, via its H 2 receptors (H 2 R), in the mediator network regulating trabecular bone loss in long bones of ovariectomized (OVX) rats. It is not known whether
this effect of histamine persists over time or involves other skeletal sites. In this study, rats were maintained for 6 months
postOVX and treated daily with saline or famotidine (10 mg kg â1 ), an H 2 R antagonist. At the end of the experimental period, femur trabecular bone mass was markedly decreased in OVX rats, whether
or not they were treated with famotidine. In contrast, in the fourth lumbar vertebra, where bone loss starts later than in
the femur, famotidine treatment attenuated the decline in trabecular bone volume, protected the trabecular architecture, maintained
the thickness of the cortices and reduced the numbers of osteoclasts and tartrate-resistant acid phosphatase-positive preosteoclasts,
whereas it had no influence on bone formation parameters. In vertebral bone marrow of OVX rats, the numbers of mast cells
(MCs) and non-MC histamine-producing cells increased, while famotidine treatment significantly diminished both cell populations.
These data show that H 2 R antagonism does not protect trabecular bone mass in the long term, and that short-term protection involves all bones. Histamine
is involved during the early phase of strong osteoclastic resorption but not during the late phase of slower resorption, suggesting
that different mediator networks control the two phases of destruction. Histamine would be part of the network mediating the
early phase.