Sex and Drugs
In a study, conducted by Ed Keogh and his colleagues of the University of Bath in England, it has been
found that men and women perceive pain
differently, both quantitatively and qualitatively. Males and females have also been found to respond to pains differently. Researchers have concluded that the reason may be hidden in genes.
The pain scientists think that men’s and women’s brains process pain through different brain circuits. One incident is the different response in men and women to
nalbuphine and morphine – two pain relieving drugs. Women are found to get more relief from nalbuphine as compared to morphine, while in men morphine is not only more effective in relieving pain, nalbuphine may increase the intensity of pain in them.
Both nalbuphine and morphine work by stimulating the brain’s endogenous – opioid receptors. But they work differently in that morphine binds to ‘mu’ receptors while nalbuphine stimulates ‘kappa’ receptors. The kappa-receptor agonists like nalbuphine do not seem to provide any pain relief in men.
Dr. Jeffrey Mogil, director of the pain genetics laboratory at McGill University, Montreal, has identified the first gene which is involved in modulating the pain thresholds in women. Variations of this gene affect the response of women to a kappa-receptor agonist called pentazocine, but not that in men. This gene also affects hair and skin colour. The study of this correlation has concluded that redheaded women with fair skin show a higher pain relief response to pentazocine.
Researchers have found two kinds of circuits in the brain – an analgesia circuit and an anti- analgesia circuit. Which circuit is activated depends on the type of receptor a drug works on as well as the dose given. For example, nalbuphine in low doses had short term effect on women, while it significantly increased pain in men among those who were treated for dental pain. But in combination with naloxone – a drug which blocks all opioid receptors – nalbuphine relieved pain in both men and women. A combination of the right proportion of these drugs in a mixture has been patented by Dr. Robert Gear and Dr. Jon Levine which works on both the sexes.
The studies conducted by the researchers included, among their findings, the conclusion that men and women cope differently with pain. Men focus more on physical aspects of pain while women focus more on the emotional aspects. That may be the reason why women experience more pain and that much more intensely than men. This mystery is still to be solved. Further studies may pinpoint whether this difference is genetic or a result of social influences.