Ovariectomized rat
Encyclopedia
Currently there is no single animal model
that identically represents the stages of osteoporosis
in humans as a whole, although there are ones available that provide a relatively close comparison. Both small animals and large animals are used depending on which aspects of the osteoporotic condition are being studied. Such animals include rats, rabbits, and sheep.
Of these animal models, the ovariectomised (OVX) rat model remains the most popular choice as it has been validated to represent the most important clinical features of estrogen
deficiency-induced (or postmenopausal) bone loss in the adult human, particularly during the early stages of osteoporosis. These include: increased rate of bone turnover with resorption exceeding formation; an initial rapid phase of bone loss followed by a much slower phase; greater loss of cancellous bone than cortical bone
; reduced intestinal calcium
absorption; some protection against bone loss by obesity
; and similar skeletal response to therapy with estrogen, tamoxifen
, bisphosphonates, parathyroid hormone
, calcitonin
and exercise.
It also offers certain advantages compared the other animal models like rabbits and sheep. These include the ability to use peripheral micro-computed tomography
(pQmicro-CT) in in vivo
micro-CT to perform in vivo analyses, cost-effectiveness, and ease of handling and housing. Because of these considerations, the OVX rat model is widely used for the studies relating to the prevention and treatment of osteoporosis in general as well as studies relating to the healing of osteoporotic fractures.
Animal model
An animal model is a living, non-human animal used during the research and investigation of human disease, for the purpose of better understanding the disease without the added risk of causing harm to an actual human being during the process...
that identically represents the stages of osteoporosis
Osteoporosis
Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...
in humans as a whole, although there are ones available that provide a relatively close comparison. Both small animals and large animals are used depending on which aspects of the osteoporotic condition are being studied. Such animals include rats, rabbits, and sheep.
Of these animal models, the ovariectomised (OVX) rat model remains the most popular choice as it has been validated to represent the most important clinical features of estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
deficiency-induced (or postmenopausal) bone loss in the adult human, particularly during the early stages of osteoporosis. These include: increased rate of bone turnover with resorption exceeding formation; an initial rapid phase of bone loss followed by a much slower phase; greater loss of cancellous bone than cortical bone
Cortical bone
Cortical bone, synonymous with compact bone, is one of the two types of osseous tissue that form bones. Cortical bone facilitates bone's main functions: to support the whole body, protect organs, provide levers for movement, and store and release chemical elements, mainly calcium. As its name...
; reduced intestinal calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
absorption; some protection against bone loss by obesity
Obesity
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
; and similar skeletal response to therapy with estrogen, tamoxifen
Tamoxifen
Tamoxifen is an antagonist of the estrogen receptor in breast tissue via its active metabolite, hydroxytamoxifen. In other tissues such as the endometrium, it behaves as an agonist, hence tamoxifen may be characterized as a mixed agonist/antagonist...
, bisphosphonates, parathyroid hormone
Parathyroid hormone
Parathyroid hormone , parathormone or parathyrin, is secreted by the chief cells of the parathyroid glands as a polypeptide containing 84 amino acids...
, calcitonin
Calcitonin
Calcitonin is a 32-amino acid linear polypeptide hormone that is producedin humans primarily by the parafollicular cells of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood calcium , opposing the effects of parathyroid hormone . Calcitonin has been found...
and exercise.
It also offers certain advantages compared the other animal models like rabbits and sheep. These include the ability to use peripheral micro-computed tomography
Tomography
Tomography refers to imaging by sections or sectioning, through the use of any kind of penetrating wave. A device used in tomography is called a tomograph, while the image produced is a tomogram. The method is used in radiology, archaeology, biology, geophysics, oceanography, materials science,...
(pQmicro-CT) in in vivo
In vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
micro-CT to perform in vivo analyses, cost-effectiveness, and ease of handling and housing. Because of these considerations, the OVX rat model is widely used for the studies relating to the prevention and treatment of osteoporosis in general as well as studies relating to the healing of osteoporotic fractures.