What may have been observed in practice as a unique and odd event that we didn’t anticipate from a physiological point of view – but that seemed to have had its origin in the force that was applied into the system – may be better understood as a chemical chain of events. Although in its bare infancy, mechanotransduction offers a means to begin to map those interactions.” Dr. McGregor notes that even though they are continually applying force through tissues and cells, chiropractors do not fully know how manipulation works. To remedy this gap in knowledge, the profession must endeavour to examine what actually takes place. Research in basic sciences is advancing and may facilitate our eventual understanding. “One of the strong areas of research is in bone development,” she observes, “whereby researchers at the University of Delaware, for exam-ple, have attempted to understand the relationship between mechanical stimulation of osteoblasts, osteoblastic activity and mechanosensitivity. Such findings may help illuminate the means by which the mechanical stimuli that chiropractors routinely impart to the musculoskeletal system have their observed effects. Hopefully future research by our profession will consider the mechanisms of action described by the basic researchers working in this arena.” The relationship of epigenetics to mechanobiology can be seen, for example, in the development of sesamoid bones, which Sarin and colleagues expressed as “mediated epigeneti-cally by local mechanical forces.” 2 The 2011 Congress on Com-putational Bioengineering has a session dedicated to mechano-biology and recent developments in epigenetics. “Influences exist at the environmental level, within the in-dividual, and within the cell at the point of the signaling path-ways,” continues Dr. McGregor. “Many factors interact in a very complex way that we do not understand. As chiropractors we are a part of interacting with those systems and right now we are beginning to say we need to pay attention to how we impact those systems. We’ve never done that before. Everything we’ve done has been on either a large environmental level or a dis-crete individual level; we have not spent the time going down to the cellular level to determine what is driving the system. The individual’s epigenetic response to a mechanical stimulus is the new frontier for us.” THE PAIN MODEL Our moder n understanding of pain includes recognition of changes that occur in an epigenetic fashion. Underlying that is a deeper mechanism that could be called “activity-dependant.” According to CMCC professor Dr. Howard Ver non, the way cells function changes them, and part of that change is at the level of genetic expression. Different proteins are produced as a result of the demands placed on particular systems. “All muscles have an initial genetic profile placing them in a particular type of muscle fibre group,” he notes. “Postural muscles, for example, have an anaerobically-based genetic pro-file that enables them to perform longstanding, static activities with very little oxygen. They have chemistry and a structure that serves them to remain ‘on’ for great lengths of time. That’s what posture is all about. “When we perform certain types of activities with these www.canadianchiropractor.ca CANADiAN CHiROPRACTOR | JUNE 2011 • 27
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