Expression of galanin and XXXX in normal bone and during @entity174 repair in the @entity35 .

@entity174 @entity1184 @entity3817 @entity49975 @entity35
The neuropeptide galanin (GAL) has recognized physiological actions in the nervous system and other tissues, but there is no documented evidence of GAL influencing normal or pathological bone metabolism. GAL expression, however, is upregulated in central and peripheral nerves following axotomy and is known to influence neural regeneration. Thus, severance of skeletal-associated nerves during @entity174 could similarly increase local GAL concentrations and thereby influence @entity174 healing. The initial aim of this study was therefore to identify the presence of GAL in normal bone and/or @entity174 by assessing the concentration and cellular localization of GAL in intact and/or @entity174 @entity35 rib, using radioimmunoassay and immunohistochemistry, respectively. Groups of @entity35 (13 weeks old) had their left sixth ribs surgically @entity174 or underwent sham surgery and then calluses and nonfractured rib samples were analyzed at 1 and 2 weeks postsurgery (n = 5-6 per group). Low (basal) concentrations of GAL were detected in control ribs, whereas at 1 and 2 weeks postfracture, callus samples contained markedly increased levels of peptide ( approximately 32- and 18-fold increase, respectively, relative to controls; P < 0.01), revealing a strong upregulation during bone healing. Plasma GAL concentrations were also increased at 2 weeks postfracture (P < 0.005). In normal (nonfractured) rib, minimal levels of @entity3817 ( @entity3817 ) were present in cortical bone, periosteum, endosteum, and surrounding skeletal muscle. In costal cartilage plates, intense GAL- @entity3817 was present in all chondrocytes of the @entity1184 zone and in a population of chondrocytes in the reserve zone. GAL- @entity3817 was not present, however, in chondrocytes in the proliferative zone of costal cartilage or skeletal muscle fibers. In @entity174 , levels of GAL- @entity3817 were moderate to intense in osteoprogenitor cells and osteoblasts, in some chondrocytes, and in cartilaginous, osseous, and periosteal matrices. Subsequent studies revealed the presence of @entity49975 -like immunoreactivity ( @entity49975 - @entity3817 ) in most cell types shown to contain GAL- @entity3817 , although the distribution of @entity49975 - @entity3817 was more extensive in reserve zone chondrocytes than that of GAL- @entity3817 ; and @entity49975 - @entity3817 also appeared in late proliferative zone chondrocytes of costal cartilage. In summary, GAL concentrations were significantly increased in @entity174 and plasma of @entity35 that underwent rib @entity174 . In addition, GAL- and @entity49975 - @entity3817 was also detected in specific cells and structures within costal cartilage, bone, and @entity174 . These results strongly implicate GAL in aspects of cartilage growth plate physiology and @entity174 repair, possibly acting in an autocrine/paracrine fashion via @entity49975 .
