From the time when the blame was squarely put on the shoulders of spirits, demons, ghosts and wrath of gods, we have come a long way in understanding and managing pain. Sure, we still don't have the complete picture , but what we know enable us to manage pain to a great extent. For example we know that the bundle of nerves inside the dorsal horn of spinal chord processes somatosensory information, nociceptive terminals relay signals to several domains in the brain, that body secretes its own brand of analgesics called endorphins and enkephalins, that these bind to opioid receptors and block pain signals , that modern day painkillers act the same way, so on and so forth..... .
We also know that physiological and psychological factors can modulate the intensity of pain. Gonadal hormones are known to influence the behaviour of one set of opioid receptors called mu receptors. Naturally the question arises- is there a significant gender difference in the sensation and perception of pain? Do male and female species respond differently to pain and its management?. In general experimental data indicate that women have a lesser threshold for pain than men. Male rats injected with the female hormone oestrogen showed lower threshold and female rats injected with testosterone the male hormone registered elevated tolerance. Certain classes of painkillers give better relief for females. Jeffrey S. Mogil, a neuroscientist with both the Dept of Psychology and the Alan Edwards Centre for Research on Pain, at the McGill University, Montreal, Canada is very clear on this topic. He states that " sex differences in pain and analgesia are real and robust." Mogil and his research team are convinced that these differences go beyond what hormones can account for. They have detected that pain pathway itself is different - in male rodents microglial cells and in female rodents T cells process pain. (By the way microglial cells are immune cells of the central nervous system and T cells are a subgroup of white blood cells.)
Preclinical research is routinely conducted using male rats only. Female rats are not included for the simple reason that their fluctuating hormonal levels might introduce unwanted variability. Perhaps it will be practical to include a set of male rats injected with prescribed levels of female hormones. Or include a parallel set of female rats.
Preclinical research is routinely conducted using male rats only. Female rats are not included for the simple reason that their fluctuating hormonal levels might introduce unwanted variability. Perhaps it will be practical to include a set of male rats injected with prescribed levels of female hormones. Or include a parallel set of female rats.
However given that Pain is forever accompanied by patient specific emotional baggage of the past, the present and the future, the need of the hour is an analytical tool for objective and unbiased measurement. Several groups are at work to realise this goal. Well, the ultimate device won't be as simple as a thermometer, but more like a brain scan. Current focus is on brain imaging using functional MRI. But it would indeed be a painstaking exercise to sift the actual pain signal from its virtual components.
Tailpiece:
According to Roman mythology, Doloros (Algea in Greek mythology) is the goddess of anguish and pain. In 1945 Dr LJB Gluzek claimed to have designed a device called Dolorimeter which could measure pain with 97% accuracy. Time magazine dated Jan 1945 published an interesting commentary on it.
References:
1. Pain : Nature Outlook -Nature 14 July 2016, Vol.535, issue 7611, S1-S19
2.Sex differences in pain and pain inhibition: multiple explanations of a controversial phenomenon. Mogil, J.S, Nature Reviews Neuroscience, 13:pp859-866, (2012.)
3. Sex differences in pain and analgesia :Mogil, J.S et al Progress in Brain Research 186, pp141-57 (2010)
4. Sex differences in pain: A brief review of clinical and experimental findings: Bartley et al British Journal of Anaesthesia vol. 111(1),pp52-58(2013)
5. Sex, Gender and Pain : A review of recent Clinical and Experimental Findings,
Fillingim et al, J. Pain 10(5) pp 447-485(2009)
Fillingim et al, J. Pain 10(5) pp 447-485(2009)
