Pain research, control

However, in individuals with increased intracranial pressure, asthma, chronic obstructive pulmonary disease, or cor pulmonale, this decrease in respiratory function may not be tolerated. Opioid-induced respiratory depression remains one of the most difficult clinical challenges in the treatment of severe pain. Research is ongoing to understand and develop analgesic agents and adjuncts that avoid this effect. Research to overcome this problem is focused on 5 receptor pharmacology and serotonin signaling pathways in the brainstem respiratory control centers. 

The endorphins are a group of naturally occurring neuroproteins that act in a manner similar to morphine to control pain. Research has shown that the biologically active part of the endorphin molecule is a simple pentapeptide called an enkephalin, with the structure Tyr-Gly-Gly-Phe-Met. Draw the complete structure of this enkephalin. 

The lOM report describes the effect of THC, the primary psychoactive ingredient in marijuana cannabinoids, which are the compounds related to THC and marijuana, the unpurified plant substances. The lOM report studied the effects of isolated cannabioids and concluded that they have a natural role in pain modulation, control of movement, and memory. The role on cannabioids in the immune system was unclear and the report concluded that the brain develops tolerance to cannabioids. While animal research demonstrated dependence on cannabioids, the potential for dependence was seen as occurring under a more narrow range of conditions than for drugs such as minor tranquilizers, opiates, cocaine, or nicotine. Withdrawal symptoms were observed in animal studies but were mild compared to drugs such as minor tranquiflzers or opiates. 

Perhaps the most striking example of this upsurge of interest has been in the area of pain research—in its genesis, expression, and, of greatest importance, its intrinsic and extrinsic control. These studies were placed on a molecular footing by the isolation and structure determination of the enkephalins (Hughes et al., 1975b)—two related peptides found in the brain with potent opiate activity—and the concomitant observation that the amino acid sequence of one of these species (met-enkephalin) was present in the protein 3-lipotropin. This led to the discovery of other... 

Shlay JC, Chaloner K et al (1998) Acupuncture and amitriptyline for pain due to HIV-related peripheral neuropathy a randomized controlled trial. Terry Beim Community Programs for Clinical Research on AIDS. JAMA 280(18) 1590-1595... 

An intriguing area of research on opioids has been the accumulating evidence for plasticity in opioid controls. The degree of effectiveness of morphine analgesia is snbject to modulation by other transmitter systems in the spinal cord and by pathological changes induced by peripheral nerve injury. Thus in neuropathic states, pain after nerve injury, morphine analgesia can be reduced (but can still be effective) and tactics other than dose-escalation to circumvent this will be briefly discussed in Chapter 21. 

There is no proven treatment for smallpox, but research to evaluate new antiviral agents is ongoing. Patients with smallpox can benefit from supportive therapy (e.g., intravenous fluids, medicine to control fever or pain) and antibiotics for any secondary bacterial infections that may occur. 

Some alternative therapies have crossed the line into mainstream medicine as scientific investigation has confirmed their safety and efficacy. For example, today physicians may prescribe acupuncture for pain management or to control the nausea associated with chemother-(40) apy. Most U.S. medical schools teach courses in alternative therapies and many health insurance companies offer some alternative medicine benefits. Yet, despite their gaining acceptance, the majority of alternative therapies have not been researched in controlled studies. New research efforts aim at testing alternative methods and providing the... 

We suspect that the assumed physiological mechanism of pain and heart responses may have facilitated self-deception in the first experiment. Most people believe that such responses are not under an individual s voluntary control. This widespread belief makes it very easy to deny to oneself that the action was deliberately enacted to make a cheerful diagnosis, for how does one intentionally pull the strings. That self-deception may occur more often and be more successful for actions (incorrectly) believed to be uncontrollable than controllable is an interesting question for further research. The possibility of a motivational placebo effect, in which the desire to have one s tolerance shifted produces actual changes in physiological tolerance thresholds, seems worth exploring. 

There have been numerous clinical studies examining the analgesic effects of TCAs in chronic pain, and the review of these is beyond the scope of this chapter. There are a number of reviews covering these studies (e.g. Onghena and van Houdenhove, 1992 McQuay et al., 1996 Feuerstein, 1997). In contrast, the effects of TCAs in acute pain have not received much attention in clinical research. There are only a few controlled studies with mixed results, reporting no effect of desipramine or amitryptiline on postoperative dental pain when given alone but enhanced... 

The effects of morphine eventually led many scientists to predict that the brain possesses its own endogenous opiate-like neurotransmitters and its own complement of endogenous opiate receptors in the brain. In the mid-i97o s research confirmed that the brain and body do indeed contain some endogenous morphine-like peptides and christenedthem endorphins. These peptides control our experience of pain by stopping the flow of pain signals into our brains, and this action is enhanced... 

Similar to opioids, the cannabinoid system appears to be intricately involved in normal physiology, specifically in the control of movement, formation of memories, and appetite control. Basic research has discovered that members of this family of compounds have the capacity to protect threatened neurons, thereby slowing neurodegenerative processes that ultimately lead to physical disability. As the function of the physiological role of endocannabinoids becomes clearer, it appears the system may be involved in the pathology of several neurological diseases, specifically multiple sclerosis, spasticity, and pain. In 1999 the German journal, Forschende Komplementar-medizin und Klassische Naturheilkunde (Research in Complementary and Classical Natural Medicine) commented ... 

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