While it doesn’t fully explain the biochemical reasons behind Opiate addiction, a recent study has noted some interesting results from long term use of opiates such heroin and morphine. While studying hypocretin-producing neurons in the human brain scientists found a notable increase in a certain subject who was later revealed to be a heroin addict. Following this they studied five postmortem brains from heroin addicts and performed tests on lab mice to find further links between the addiction and the increase in cells.
These tests resulted in an increase number of the neurons in normal mice and a restoration in the neurons in mice that had these neurons partially depleted. By restoring these neurons in the mice they were able to decrease expression of cataplexy which is the iconic symptom of narcolepsy. This wasn’t entirely promising as a means of treating narcolepsy as the neuron increase required long term administration of morphine. But it may prove an essential piece of the puzzle for figuring out addiction and future treatments.
The changes in brain function that perpetuate opiate addiction are unclear. In our studies of human narcolepsy, a disease caused by loss of immunohistochemically detected hypocretin (orexin) neurons, we encountered a control brain (from an apparently neurologically normal individual) with 50% more hypocretin neurons than other control human brains that we had studied. We discovered that this individual was a heroin addict. Studying five postmortem brains from heroin addicts, we report that the brain tissue had, on average, 54% more immunohistochemically detected neurons producing hypocretin than did control brains from neurologically normal subjects.
Similar increases in hypocretin-producing cells could be induced in wild-type mice by long-term (but not short-term) administration of morphine. The increased number of detected hypocretin neurons was not due to neurogenesis and outlasted morphine administration by several weeks. The number of neurons containing melanin-concentrating hormone, which are in the same hypothalamic region as hypocretin-producing cells, did not change in response to morphine administration. Click Here to Continue Reading