Yet the existence of a typical heroin addict in prohibitionist society can still be unpleasant at times. Contemporary opioid drugs, natural and synthetic alike, are flawed. More seriously, when taken in excess, today's opioids can cause respiratory depression . This is a consequence of their stimulation of the mu-2 receptors in medullary respiratory centres of the brain. These problems are exacerbated a thousandfold, however, by the illegal status of narcotics in contemporary society.
Pharmacological education is non-existent, whereas it ought to be part of the core curriculum.
Thus dynorphin activity at the kappa receptors tonically inhibits the release of dopamine from the mesolimbic terminals. Today, people vary hugely in their sensitivity to pain . This sensitivity is genetically regulated. This number is controlled by single gene, the mu opioid receptor gene. Pain-sensitivity is diminished when the receptors are present in relative abundance.