Related Experiment Video
Updated: Jul 7, 2026
06:59
Trabecular Bone Microarchitecture Evaluation in an Osteoporosis Mouse Model
Published on: September 8, 2023
Bone growth and turnover in progesterone receptor knockout mice
David J Rickard1, Urszula T Iwaniec, Glenda Evans
1Mayo Clinic, Rochester, Minnesota 55905, USA.
Endocrinology
|February 16, 2008
Summary
Progesterone receptor (PR) signaling is not essential for bone growth. However, PR signaling appears to reduce bone mass accumulation at certain skeletal sites during adolescence in mice.
Area of Science:
- Endocrinology
- Skeletal Biology
- Reproductive Biology
Background:
- The role of progesterone receptor (PR) signaling in skeletal metabolism remains debated.
- Understanding PR's necessity for normal bone growth and turnover is crucial.
Purpose of the Study:
- To investigate whether progesterone receptor (PR) signaling is essential for normal bone growth and turnover.
- To determine the specific effects of PR signaling on bone mass accumulation and remodeling.
Main Methods:
- Histomorphometric and microcomputed tomography analyses were performed on homozygous female PR knockout (PRKO) mice.
- Bone samples were analyzed at 6, 12, and 26 weeks of age.
Main Results:
- PR knockout mice exhibited normal body weight, uterine weight gain, and tibia longitudinal bone growth.
- Increased total, cancellous, and cortical bone mass were observed in the humerus of 12-week-old PRKO mice.
- At 26 weeks, PRKO mice showed a 153% greater cancellous bone area in the proximal tibia metaphysis, associated with elevated bone formation and reduced osteoclast perimeter.
Conclusions:
- PR signaling is not essential for overall bone growth and turnover in mice.
- PR signaling appears to attenuate the accumulation of cortical and cancellous bone mass at specific skeletal sites during adolescence.
Related Concept Videos
01:40Bone Remodeling
Bone remodeling is a continuous and balanced process of bone resorption by osteoclasts and bone formation by osteoblasts. In adults, it helps maintain bone mass and calcium homeostasis. While mechanical stress can stimulate turnover as part of the normal maintenance and reparative process, several hormones also regulate bone remodeling.
01:29Bone Disorders
Aging and its effect on bone remodeling is the most common cause of bone disorders. In young and healthy people, bone deposition and resorption happen at an equal rate to maintain optimal bone health.
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
01:31Osteoclasts in Bone Remodeling
Osteoclasts are cells responsible for bone resorption and remodeling. They originate from hematopoietic progenitor cells present in the bone marrow. Numerous progenitor cells fuse to form multinucleated cells, each with 10-20 nuclei. A single osteoclast has a diameter of 150 to 200 µM. These cells have ruffled borders that break down the underlying bone tissue and release minerals such as calcium into the blood in bone resorption. Osteoclasts cling to bones with their ruffled edges during bone...
01:17Hormones and Bone Tissue
The endocrine system produces and secretes hormones, which interact with the skeletal system. These hormones control bone growth, maintain bone once it is formed, and remodel it.
Hormones That Influence Osteoblasts and/or Maintain the Matrix
Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth. This happens in several ways: first, it triggers chondrocyte...
Hormones That Influence Osteoblasts and/or Maintain the Matrix
Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth. This happens in several ways: first, it triggers chondrocyte...