title: [Relationship between the levels of sex hormones and loss of bone mass in aging male rats].
abstract: OBJECTIVE
  To investigate the relationship between the level of sex hormones and the loss of bone mass in aging male rats.
  
  
  METHODS
  Thirty male Sprague-Dawley rats were equally divided into five age groups and sacrificed at 35, 70, 160, 700 and 800 postnatal days (PD) , followed by measurement of the % Tb x Ar, Tb x Th, Tb x N and Tb x SP by bone histomorphometry and detection of the levels of serum testosterone (T) and estradiol (E2) by radioimmunoassay. The relationship between the changes of the T and E2 levels and those of bone histomorphometry was analyzed.
  
  
  RESULTS
  T and E2 levels were closely correlated with the bone mass in the aging male rats. The changes in T and E2 levels were simultaneous with those in the bone mass with the growth of the rats. T, E2, % Tb x Ar and Tb x N reached the peak in the 70 and 160 PD groups, and markedly decreased in the 700 PD group except Tb x Th and Tb x SP. The T levels in the 35, 70, 160, 700 and 800 PD groups were (118.53 +/- 18.35) ng/dl, (345.49 +/- 54.63) ng/dl, (368.83 +/- 60.03) ng/dl, (61.15 +/- 21.12) ng/dl and (60.35 +/- 19. 27) ng/dl, changing simultaneously with the E2 levels, which were (10.35 +/- 1.82) pg/ml, (16.92 +/- 3.13) pg/ml, (17.20 +/- 2.51) pg/ml, (5.87 +/- 2.34) pg/ml and (5.53 +/- 2.48) pg/ml, respectively. The metrological parameters of the bone structure in the five groups were as follows, Tb x Ar: (19.52 +/- 2.23)%, (26.28 +/- 2.18) %, (28.37 +/- 1.21) %, (15.62 +/- 1.68) % and (14.21 +/- 0.89) %; Tb x Th: (35.45 +/- 1.63) microm, (50.13 +/- 3.58) microm, (60.23 +/- 8.25) microm, (75.62 +/- 9.72) microm and (78.78 +/- 11.21) microm; Tb x N: (5.98 +/- 1.21) n/mm, (8.07 +/- 0.86) n/mm, (8.30 +/- 1.22) n/mm, (2.63 +/- 1.35) n/mm and (2.48 +/- 1.62) n/mm; Tb x SP: (126.34 +/- 18.15) microm, (136.26 +/- 15.27) microm, (261.08 +/- 76.43) microm, (323.12 +/- 78.12) microm and (330.23 +/- 50.20) microm.
  
  
  CONCLUSIONS
  Changes in the levels of sex hormones are closely correlated with those of bone mass. Both testosterone and estradiol are essential for bone development and bone mass maintenance.
authors: Department of Physiology, Guangdong Medical College, Zhanjiang, Guangdong 524023, China.
authors: Ping
authors: P
authors: Zhong
authors: Xi-Yi
authors: XY
authors: Liu
mesh_terms: D000375:Aging; D000818:Animals; D015519:Bone Density; D001846:Bone Development; D001842:Bone and Bones / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism / Q000473:pathology; D004958:Estradiol / Q000097:blood*; D008297:Male; D010024:Osteoporosis / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D004958:Estradiol