Al­co­hol changes how mem­o­ries are formed on a molec­u­lar level

Af­ter three glasses, with an hour break in be­tween, the path­way doesn’t re­turn to nor­mal af­ter 24 hours. We think this per­sis­tence is likely what is chang­ing the gene ex­pres­sion in mem­ory cir­cuits

The Borneo Post - Nature and health - - Front Page -

Ac­cord­ing to a study conducted by Karla Kaun, Emily Petruc­celli and a team at Brown Univer­sity in the United States, pub­lished in the jour­nal Neu­ron, a few glasses of al­co­hol in the evening changes the way our mem­o­ries are formed on a molec­u­lar level. For the study, the re­searchers de­cided to in­ves­ti­gate the role of mol­e­cules and genes in the en­cod­ing of mem­o­ries linked to re­ward sys­tems.

Their start­ing point was a rel­a­tively sim­ple ques­tion: why do peo­ple in­sist on con­sum­ing sub­stances that have un­pleas­ant ef­fects on their bod­ies and minds? Drugs of abuse both hard and soft (opi­ates, al­co­hol etc.) of­ten re­sult in ad­verse ef­fects that vary in in­ten­sity: nau­sea, vom­it­ing, headaches, hang­overs... Why is it that we only re­mem­ber good feel­ings as­so­ci­ated with these neu­ro­tox­ins, and not the bad ones?

Go­ing to work on fruit flies which they trained to like al­co­hol, the re­searchers in­ves­ti­gated the roles of dif­fer­ent genes and pro­teins in­volved in ad­dic­tion and re­ward sys­tems. The first step was to iden­tify mol­e­cules that change when there is a yearn­ing for al­co­hol or drugs, or a feel­ing of with­drawal; an im­por­tant as­pect of the pro­ject that could pave the way for new treat­ments for ad­dicts, which re­duce the in­ten­sity of pleas­ant mem­o­ries linked to drugs of abuse.

The re­searchers found that one of the main pro­teins that caused the flies to seek al­co­hol was “Notch”. Notch acts as the first domino in sig­nalling path­ways that play a role in em­bryo and brain de­vel­op­ment in all an­i­mals in­clud­ing hu­mans. The re­searchers also dis­cov­ered that dopamine-2-like re­cep­tor genes in­volved in these path­ways were also af­fected by al­co­hol. These genes produce a pro­tein on neu­rons that recog­nises dopamine, a feel-good neu­ro­trans­mit­ter known to play a part in the en­cod­ing of pos­i­tive mem­o­ries.

In the re­ward path­way they stud­ied, the re­searchers found that molec­u­lar sig­nalling was un­changed, and that the amount of pro­tein cre­ated re­mained the same. How­ever, there was a sub­tle change in the ver­sion of the pro­tein pro­duced. Kaun ex­plained their find­ings with an anal­ogy for peo­ple: “If this works the same way in hu­mans, one glass of wine is enough to ac­ti­vate the path­way, but it re­turns to nor­mal within an hour. Af­ter three glasses, with an hour break in be­tween, the path­way doesn’t re­turn to nor­mal af­ter 24 hours. We think this per­sis­tence is likely what is chang­ing the gene ex­pres­sion in mem­ory cir­cuits.” – Re­laxnews

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