Moredopamine
Bluelighter
I've always noticed that I had an abnormal insensitivity to recreational opioids. I have also known for a while that there may be a cross-tolerance of sorts between endogenous opioids and those administered exogenously.
Today I was casually sifting through the literature and noticed (yet another) abstract that supports my above speculations:
Recent work has shown that chronic exercise is associated with a reduction in the pain-relieving actions of opioid drugs in experimental animals. To determine whether this reduction represents an interaction between exogenously administered opioids and the endogenous opioid system, or is the result of altered drug pharmacokinetics, the antinociceptive actions of morphine and its metabolite, morphine-6-glucuronide (M6G), were compared in active and inactive female Long-Evans rats. Active animals were housed in running wheels and inactive animals in standard laboratory cages for 3 weeks preceding determinations of antinociception using the tail-flick test. At the end of the 3-week period, active rats were running the equivalent of 9-11 km a day. Antinociceptive responses, determined following subcutaneous injections of either morphine (0.625-20 mg/kg) or M6G (0.3-10.0 mg/kg), were significantly reduced in active rats relative to inactive rats. This reduction was manifested by both a lower magnitude of antinociception, and a shorter duration of antinociception after drug administration in active compared to inactive rats. This reduction was not associated with alterations in the estrous cycle or with differences in body weight between the active and inactive animals. The present results support the hypothesis that cross-tolerance develops between endogenous opioid peptides released in response to exercise and exogenously administered opioid drugs.
http://www.ncbi.nlm.nih.gov/pubmed/11564474
I have always enjoyed running and especially enjoyed the incredible "runner's high" that is almost certainly caused by central mu opioid receptor activation. But whenever I use, say, morphine, I always seem to get a minimal high at best.
Now this study has its limitations in that it was performed on rats but it is well established that the similarities between rats/humans are quite profound.
So to get to the point: Are there any running-enthusiasts here that have noticed such a phenomenon when they use opiates?
Note that I am strictly referring to long-distance running since anaerobic exercise/other lighter physical activities have minimal mu opioid receptor activation as a result of the physical exertion of the activity. But anyone may respond of course!
Today I was casually sifting through the literature and noticed (yet another) abstract that supports my above speculations:
Recent work has shown that chronic exercise is associated with a reduction in the pain-relieving actions of opioid drugs in experimental animals. To determine whether this reduction represents an interaction between exogenously administered opioids and the endogenous opioid system, or is the result of altered drug pharmacokinetics, the antinociceptive actions of morphine and its metabolite, morphine-6-glucuronide (M6G), were compared in active and inactive female Long-Evans rats. Active animals were housed in running wheels and inactive animals in standard laboratory cages for 3 weeks preceding determinations of antinociception using the tail-flick test. At the end of the 3-week period, active rats were running the equivalent of 9-11 km a day. Antinociceptive responses, determined following subcutaneous injections of either morphine (0.625-20 mg/kg) or M6G (0.3-10.0 mg/kg), were significantly reduced in active rats relative to inactive rats. This reduction was manifested by both a lower magnitude of antinociception, and a shorter duration of antinociception after drug administration in active compared to inactive rats. This reduction was not associated with alterations in the estrous cycle or with differences in body weight between the active and inactive animals. The present results support the hypothesis that cross-tolerance develops between endogenous opioid peptides released in response to exercise and exogenously administered opioid drugs.
http://www.ncbi.nlm.nih.gov/pubmed/11564474
I have always enjoyed running and especially enjoyed the incredible "runner's high" that is almost certainly caused by central mu opioid receptor activation. But whenever I use, say, morphine, I always seem to get a minimal high at best.
Now this study has its limitations in that it was performed on rats but it is well established that the similarities between rats/humans are quite profound.
So to get to the point: Are there any running-enthusiasts here that have noticed such a phenomenon when they use opiates?
Note that I am strictly referring to long-distance running since anaerobic exercise/other lighter physical activities have minimal mu opioid receptor activation as a result of the physical exertion of the activity. But anyone may respond of course!
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Perhaps. But it would be interesting nonetheless.
) or doing whatever. I suspect this is directly correlated with endogenous production synergizing with the exogenous drug. And without a doubt, the more strenuous the exercise, the more pronoucned the effects of the Opioid become, IME.