Neurobiology for the drunk
May 1, 2018 9:00 PM   Subscribe

What is the biochemical mechanism of an alcohol-induced blackout? I want genes, I want pathways, and most of all I want to establish whether there is any aspect of the brain's activity during a blackout that could be considered neuroprotective, rather than just a consequence of toxicity.

OK, so I read this NIH article and as I understand it, the activity of hippocampal CA1 pyramidal cells, which communicate extensively with the neocortex, is suppressed by high blood alcohol. Long term potentiation, which is the long-lasting neuronal changes in the hippocampus associated with forming new memories, is dependent on the activation of the NMDA receptor, which is a receptor for the neurotransmitter glutamate. Alcohol inhibits this receptor, preventing the neuronal changes it mediates, though "other neurotransmitter systems are probably involved." Also alcohol suppresses the theta rhythm emitted by the medial septum, which influences hippocampal CA1 pyramidal cell information processing. And other stuff happens. Or something. I'm pretty drunk.

But alright, I'm thinking, this is just toxicity.

But the scientists at Gizmodo say this: "Alcohol interferes with the receptors in the hippocampus that transmit glutamate, a compound that carries signals between neurons. During this interference, alcohol prevents some receptors from working, while activating others. This process causes the neurons to create steroids [emphasis mine] that then prevent neurons from communicating with each other properly, thus disrupting long-term potentiation (LTP), a process believed necessary for learning and memory."

Steroids? What steroids? Could this be the neuroprotection I'm looking for? Some drunk girl told me that the process by which the brain fails to form new memories during a blackout either is itself neuroprotective in some way, or activates a separate neuroprotective pathway. If there is a specifically immune response in the brain -- and there would be, right? -- it doesn't count.

Taking the time getting to the bottom of it on PubMed with the very little info I have to search on would kinda be a party foul.

So neuroscientists, what say you? Help a motha out?
posted by pH Indicating Socks to Science & Nature (1 answer total) 8 users marked this as a favorite
I'm not sure what you mean by neuroprotective. Alcohol is pretty well-established as toxic to neurons. Especially in the cerebellum which controls coordination and balance (surprise). With chronic alcoholism you get degeneration of the entire memory circuit, which leads to the somewhat wild (for observers) Korsakoff syndrome. I have no idea what "steroids" the Gizmodo writers are referring to, but your brain does not like steroids in general; just ask anyone who has had to take high-dose prednisone or dexamethasone or methylpred how loopy they were.

Source: neurologist who has taken care of way too many people with complications of alcohol use (even those you wouldn't consider "alcoholic.") Of course, I write this while drinking a lager because it's 90 degrees right now. So take that for what it's worth.
posted by basalganglia at 4:12 PM on May 2, 2018 [4 favorites]

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