Latvijas Lauksaimniecības universitātes raksti nr. 18 (313) , 2007 ...

M. Pilmane et al. Investigation of Cow Bone Tissue StructureDistribution of relative number of the osteocytes and chondrocytes containing bonemorphogenetic protein, growth factor, and matrix metalloproteinases andthe occurrence of apoptosis in the visual field of cow’s humerusTable 2No.BMP2/4 FGFR1 Apoptosis(TUNEL)MMP2MMP9C B C B C B C B C B1. + – +++ + +++ + ++++ – ++++ ++2. + + ++++ + ++++ ++ – + +++ +++3. + + ++++ + ++++ ++ +++ +++ ++++ ++4. + + +++ + +++ ++ +++ – ++ +5. + – +++ + +++ ++ ++ + ++ +Notations: C – cartilage; B – bone; MMP – matrix metalloproteinasis; BMP – bone morphogenetic protein;FGFR – fibroblast growth factor receptor;– – lack of cells containing BMP2/4, FGFR1, MMP2, MMP9, and absence of apoptosis;+ – small number of cells containing BMP2/4, FGFR1, MMP2, and MMP9;++ – moderate number of cells containing BMP2/4, FGFR1, MMP2, and MMP9;+++ – numerous cells containing BMP2/4, FGFR1, MMP2, and MMP9;++++ – significant number of cells containing BMP2/4, FGFR1, MMP2, and MMP9.during lactation (Benzie et al., 1955). Bone providesCa for milk synthesis in lactating dairy cows (Horstet al., 1997). Normally calcium found in cow’s milkis supplied from both feeding and bone-resorptionsources in approximately equal proportions (Maylinand Krook, 1982). However, the negative calciumbalance has been particularly noticed in lactatingcattle after calving (Beighle, 1999).The other important changes in bone werevariations of osteocytes per mm 2 and alsothinned trabecules in spongy bone. This might beconnected to the bone disease like osteoporosis,because during this disorder morphofunctionalactivity of osteoblasts is usually changed, whichis followed by decreased bone formation andchanges in osteocyte number. So, normally inhealthy humans, number of osteocytes decreasesfor one third part from about 30 years of age until90 years. Aging changes in bone cell number incows are not known, however, we suggest aboutpersistence of the same morphopathogeneticalprinciple in these animals. It means that number ofosteocytes increases while their lacunae decrease,because osteoblasts produce lesser amount ofbone substance in comparison with intact bone,which explains the thinned trabeculae (Mullenderet al., 1996). Additionally, osteoporosis is the mostcommon type of bone disease in humans and alsoa problem in high productive cows. Osteopenia inthis disease means also decrease in the amount ofcalcium and phosphorus in the bone, bones canbecome weak and brittle, thus increasing the riskfor fractures (Dou, 2006). Disturbances in cows’organism metabolism (milk fever) and skeletalfluorosis are diseases bounded with osteoporosis.These bone diseases have been described in someregions of Canada (Obel, 1971; Shupe, 1972).Interesting data have been found about presence ofgrowth factor BMP in bone and cartilage of seeminglyhealthy cows, where it is known to stimulate growth.Osteoinduction is the process of building, healing andremodeling of bone stimulated by bone morphogeneticproteins (Pecina et al., 2002). The investigations ofBMP have discovered a family of these substances inhuman blood and bones able to promote the formationof bone and skeleton and to help mend broken bones(Reddi, 1994; Sakou, 1998).The role of BMP in the cows investigated in thepresent research seems more compensatory givingevidence about stimulating of growth also in adultanimals with some problems in bones. FGFR wasdetected mainly in cartilage in our animals and in lesseramount it was expressed by bone cells. The researchsuggests correlations and interactions between FGFRand apoptosis, and both matrix metalloproteinases inwhich distribution the same relation was observed. Themost important interaction between all these indicesindicates the growth and proliferation stimulating roleof FGF in the background of degradation in matrix,mainly observed in cartilage (despite its almostunchanged structure in routine slides) and apoptosis,also mainly affecting the cartilage. The relations ofthese factors also discover the real damage of the samehyaline cartilage. Our data respond to the data aboutfibroblast growth factors as family of growth factorsare involved not only in embryonic development,LLU Raksti 18 (313), 2007; 51-5755