Osteoporosis

Osteoporosis

A condition characterized by weakness and brittleness of the bones.

Osteoporosis means “porous bone.” If you look at healthy bone under a microscope, you will see that parts of it look like a honeycomb. If you have osteoporosis, the holes and spaces in the honeycomb are much bigger than they are in healthy bone. This means your bones have lost density or mass and that the structure of your bone tissue has become abnormal. As your bones become less dense, they also become weaker and more likely to break.

While the body is perpetually absorbing and replacing bone tissue, sufferers of osteoporosis do not create new bone tissue at a sufficient rate in comparison to bone tissue removal. Many people with osteoporosis don’t know they have the condition until they sustain a bone injury such as a fracture. The symptoms of osteoporosis are quite limited, including back pain and the loss of height, while some individuals can experience severe pain with common daily activities, such as coughing and bending over.

About 54 million Americans have osteoporosis and low bone mass, placing them at increased risk for osteoporosis. Studies suggest that approximately one in two women and up to one in four men age 50 and older will break a bone due to osteoporosis.

The Past

Pharmaceutical prescriptions include:

• Calciltriol – Calcitriol is a form of vitamin D. It works by promoting proper absorption and use of calcium and phosphate by the body in normal bone development and maintenance.
• Raxolifene – Raloxifene is a selective estrogen receptor modulator (SERM). It works in osteoporosis by decreasing bone breakdown and thinning that may occur in women after menopause. It works to decrease the risk of invasive breast cancer by blocking estrogen in breast and uterine tissue.
• Zoledronic acid – Zoledronic acid inhibits the release of calcium from bones.
• Pamidronic acid – Pamidronic acid treats bone damage caused by Paget’s disease, multiple myeloma, osteoporosis or breast cancer that has spread to the bones. This medicine is a bisphosphonat.

Physical therapy is also common to strengthen the bones, while radiologists, orthopedic surgeons and geriatricians are also oftentimes called upon to help treat the condition.

Calcium supplements and healthy diet and lifestyle are also commonly employed by sufferers of osteoporosis to combat the condition.

The Plant

THC is the most commonly cited cannabinoid used in the treatment and prevention of osteoporosis. It is THC’s activation of the CB1 and CB2 cannabinoid receptors that is believed to be responsible for the positive interaction.

CB1 and CB2 Cannabinoid Receptors

Cannabinoids interact with pathways in the body known as receptors. Many receptors exist in the body, but cannabinoids interact specifically with two types.

The two types of cannabinoid receptors are called CB1 and CB2. Both are found throughout the body, but are most common in the brain and immune system. When cannabinoids activate CB1 or CB2 receptors, they change the way the body functions.

CB1 receptors are responsible for marijuana’s psychoactive effects. They are present in many areas of the brain and play a role in memory, mood, sleep, appetite and pain sensation.

CB2 receptors are responsible for marijuana’s anti-inflammatory effects. They are found in immune cells and work to reduce inflammation. Inflammation is an immune response and is believed to be a factor in many diseases and conditions.

In the January 2006 issue of the Proceedings of the National Academy of Sciences, investigators at the Bone Laboratory of the Hebrew University in Jerusalem reported that the administration of the synthetic cannabinoid agonist HU-308 slowed the development of osteoporosis, stimulated bone building and reduced bone loss in animals. Follow up research published in the Annals of the New York Academy of Sciences in 2007 reported that the activation of the CB2 cannabinoid receptor reduced experimentally-induced bone loss and stimulated bone formation.  Investigators have previously reported that mice deficient in the CB2 cannabinoid receptor experienced age-accelerated bone loss reminiscent of human osteoporosis.

Scientists now speculate that the main physiologic involvement of specific endocannabinoid receptors (CB2 receptors) is to maintain:

Bone remodeling at balance, thus protecting the skeleton against age-related bone loss,leading some experts to believe that cannabinoids may be “a promising target novel target for anti-osteoporotic drug development.

The Patient

Cannabinoid treatment and prevention of osteoporosis first emerged in research in the early 1990s. However, there has been no clinical research on humans to date. Studies in animal models have provided promising indications that cannabinoid treatment can be effective in managing osteoporosis.

The CB1 receptor is present mainly in skeletal sympathetic nerve terminals, thus regulating the adrenergic tonic restrain of bone formation. CB2 is expressed in osteoblasts and osteoclasts, stimulates bone formation, and inhibits bone resorption. Because low bone mass is the only spontaneous phenotype so far reported in CB2 mutant mice, it appears that the main physiologic involvement of CB2 is associated with maintaining bone remodeling at balance, thus protecting the skeleton against age-related bone loss.