Journal of Nippon Medical School: Vol.67 No.1 page.018

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ArticleTitle Femoral bone density and changes therein associated with differing histories of pregnancy and lactation in aged rats

AuthorList Joji Matsumoto¹, Sanpei Kobayashi², Saburo Kikuchi² and Tsutomu Araki²

Affiliation ¹Ishikawa Hospital, Urawa, ²Department of Obstetrics and Gynecology, Nippon Medical School

Language EN

Volume 67

Issue 1

Year 2000

Page 18-23

Received August 19, 1999

Accepted October 22, 1999

Keywords pregnancy, lactation, aged rat, bone density

Abstract Objective: To examine the effect of prior pregnancy and lactation on bone density in aged rats. Materials and Methods: 2 month-old female Fischer-344 rats were divided into 4 groups: 1)13 rats were allowed to get pregnant and to nurse their offspring for two or three cycles; 2)14 rats were allowed to get pregnant two or three times and were immediately separated from their young after each delivery prior to lactation; 3)10 rats were not allowed to become pregnant; and 4)7 rats were sacrificed at the beginning of the experiment. All rats were fed ad libitum. After the rats had completed two or three pregnancies with or without subsequent lactation, all were fed a restricted diet until they were 25 months old (aged rats). Then they were sacrificed and both femurs were removed from each rat. One bone was used for analysis of mineral content and the other bone was used for photodensitometry of the diaphysis. Results: 31 rats (83.8% ) survived until they were sacrificed. The femurs of the aged rats showed increased ash weight compared to those of 2 month-old rats. Aged rats with prior pregnancies with or without subsequent lactation had higher femoral ash weight than those without prior pregnancies. There were no differences among aged rats in regard to marrow diameter, bone diameter, cortical width or bone density of the diaphysis in femur by photodensitometry. Conclusion: In aged rats, past pregnancies but not lactation were related to increases in bone density of the femur.

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ArticleTitle	Femoral bone density and changes therein associated with differing histories of pregnancy and lactation in aged rats
AuthorList	Joji Matsumoto¹, Sanpei Kobayashi², Saburo Kikuchi² and Tsutomu Araki²
Affiliation	¹Ishikawa Hospital, Urawa, ²Department of Obstetrics and Gynecology, Nippon Medical School
Language	EN
Volume	67
Issue	1
Year	2000
Page	18-23
Received	August 19, 1999
Accepted	October 22, 1999
Keywords	pregnancy, lactation, aged rat, bone density
Abstract	Objective: To examine the effect of prior pregnancy and lactation on bone density in aged rats. Materials and Methods: 2 month-old female Fischer-344 rats were divided into 4 groups: 1)13 rats were allowed to get pregnant and to nurse their offspring for two or three cycles; 2)14 rats were allowed to get pregnant two or three times and were immediately separated from their young after each delivery prior to lactation; 3)10 rats were not allowed to become pregnant; and 4)7 rats were sacrificed at the beginning of the experiment. All rats were fed ad libitum. After the rats had completed two or three pregnancies with or without subsequent lactation, all were fed a restricted diet until they were 25 months old (aged rats). Then they were sacrificed and both femurs were removed from each rat. One bone was used for analysis of mineral content and the other bone was used for photodensitometry of the diaphysis. Results: 31 rats (83.8% ) survived until they were sacrificed. The femurs of the aged rats showed increased ash weight compared to those of 2 month-old rats. Aged rats with prior pregnancies with or without subsequent lactation had higher femoral ash weight than those without prior pregnancies. There were no differences among aged rats in regard to marrow diameter, bone diameter, cortical width or bone density of the diaphysis in femur by photodensitometry. Conclusion: In aged rats, past pregnancies but not lactation were related to increases in bone density of the femur.
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