ANNALS OF ANATOMY The effect of estrogens and dietary calcium deficiency on the extracellular matrix of articular cartilage in G6ttingen miniature pigs Horst Claassen, Frank Hornberger, Katharina Scholz-Ahrens*, Michael Schiinke, Jiirgen Schrezenmeir*, and Bodo Kurz Anatomisches Institut der Universitfit Kiel, Olshausenstral3e 40, 24098 Kiel, and *Institut ftir Physiologie und Biochemie der Ern~ihrung der Bundesanstalt fiir Milchforschung, Hermann-Weigmann-Stral3e 1, 24103 Kiel, Germany Summary. Clinical observations have suggested that estro- gens are involved in the pathogenesis of postmenopausal osteoarthritis (OA). However, positive and negative asso- ciations between the incidence of OA and serum estrogen concentrations have been reported. In contrast to this, os- teoporosis is regarded as a disease with a strong estrogen- dependent component. Moreover, there is an interaction between estrogen and calcium deficiency: calcium supple- mentation potentiates the effect of estrogen therapy. The present study was designed to investigate how estrogen deficiency affects the articular cartilage depending on cal- cium supply. The distribution of different types of glycos- aminoglycans and collagens can be used as an indicator for extracellular matrix changes induced by estrogen defi- ciency. Different levels of dietary calcium were therefore fed to intact and ovariectomized G6ttingen miniature pigs for one year before articular cartilage was harvested. The histochemical staining for heavy sulfated glycosaminogly- cans in the extracellular matrix of ovariectomized minia- ture pigs, especially of those fed with a low calcium diet, was stronger in comparison to intact animals. In intact an- imals type If-collagen was immunodetected in all zones of unmineralized and mineralized articular cartilage, while immunostaining for this protein was negative to weak in the deep radiated fiber zone of ovariectomized minipigs. These results suggest that the synthesis of heavy sulfated glycosaminoglycans and immunohistochemically detectable type II-collagen is possibly influenced by estro- gen deficiency. In conclusion, under estrogen deficiency, the extracellular matrix of articular cartilage underwent Correspondence to: H. Claassen E-mail: horst.cIaasSen@med.uni-rostock.de similar changes to those observed in physiologically aging cartilage where keratan sulfate is increased as a heavy sulfated glycosaminoglycan. Key words: Articular cartilage - Estrogen - Calcium - Ovariectomy - Miniature pigs - Histology Introduction Osteoarthritis (OA) is a group of clinically heterogenous disorders characterized by the pathological features of hyaline articular cartilage loss and subchondral bone re- action. A variety of clinical, pathological and epidemiolo- gical data suggest that generalized OA may be hormonally mediated (Spector and Campion 1989; Spec- tor et al. 1997; Wluka et al. 2000). Population studies indi- cate the extremely gender-dependent prevalence of OA (Lawrence 1977; Felson 1990; Nevitt et al. 1996). In wo- men it commonly affects multiple joints and is usually more severe than in men (Lawrence 1977; Felson 1990). The apparent predominance of women presenting with polyarticular symptoms in middle age has fuelled specula- tions that there may be some relation between the onset of OA and the hormonal changes in climacterium. This is why some authors have presumed that OA is caused by a lack of estrogens (Deqneker 1985). Ovariectomy is an established procedure to simulate the hormonal condition of postmenopausal women (Wronski et al. 1989). With respect to bone metabolism pigs are closer to humans than other species. Miniature pigs have been used as models to investigate bone miner- alization in the neonatal (Schanler et al. 1991) or in the II Ann Anat (2002) 184:141-148 © Urban & FischerVerlag http:llwww.urbanfischer.de/joumalslannanat 0940-9602102118412-141 $15.0010