Histamine affects alcohol-related behaviour

The histamine-3 receptor is important in terms of alcohol-related behaviour, and a drug affecting that receptor may have qualities that alter alcohol-related behaviour.

This appears in the study headed by Pertti Panula entitled "Tuberomamillary nucleus neurons, histamine and H3 receptor in hypothalamic regulation of alcohol addiction" which is part of the Substance Use and Addictions research programme of the Academy of Finland.

"Whether these histamine-3 receptor drugs help in the treatment of human alcoholism will probably be clear when the results of the currently ongoing clinical trials become public. The drugs are currently being tested for the treatment of conditions such as observation disorders, sleep disorders and narcolepsy," says Professor Panula.

In addition to the well-known dopamine and serotonin, neurotransmitters that are important to the functioning of the brain also include histamine, which is better known for the regulation of allergies and stomach functioning. The histamine system of the brain is important in the regulation of the sleep-waking rhythm. There is also an extensive histamine system in the human brain.

In Professor Panula's previous studies it was observed that the brain histamine content of a rat population that liked to drink alcohol was higher compared with other rat populations. The alcohol consumption of these rats was reduced by giving the rats an agent that blocks the new histamine-3 receptor that was discovered in the studies. These studies showed that the histamine system of the brain is part of the mechanism that regulates alcohol consumption.

The latest studies used mice in whose brain the histamine producing enzyme and, consequently, histamine is completely lacking. These mice did not become livelier after receiving alcohol as did the mice in the control group. On the other hand, the rewarding pleasure effect of alcohol was stronger in the mice lacking histamine compared with normal mice.

It was also observed in the study that the effects of alcohol that cause liveliness and pleasure changed noticeably when a histamine-3 receptor blocker was used. The results suggest that, in addition to the use of alcohol, transmitter histamine also contributes to the transmission of the stimulating and pleasing effect of alcohol in the brain.