‘Rush hours’ change how body works

Lesotho Times - - Health -

LONDON — A pair of “rush hours” ev­ery day rapidly change the way tis­sues through­out the body work, sci­en­tists have dis­cov­ered.

The an­i­mal study, in Pro­ceed­ings of the Na­tional Academy of Sciences, mon­i­tored the func­tion of cells, in 12 tis­sues, through the day. It found large shifts in ac­tiv­ity just be­fore dawn and dusk.

Ex­perts said the find­ings could help time med­i­ca­tion to hit sweetspots in the body clock.

The body’s in­ter­nal clock is known to drive huge changes - it al­ters alert­ness, mood, phys­i­cal strength and even the risk of a heart at­tack in a daily rhythm.

A team at the Univer­sity of Penn­syl­va­nia in­ves­ti­gated the im­pact of the time of day on the way DNA func­tions in ex­per­i­ments on mice. Ev­ery two hours they looked at sam­ples from the kid­ney, liver, lung, adrenal gland, aorta, brain­stem, cere­bel­lum, brown fat, white fat, heart, hy­po­thal­a­mus, lung and skele­tal mus­cle.

They showed that 43 per­cent of genes, sec­tions of DNA, in­volved in pro­tein man­u­fac­ture al­tered their ac­tiv­ity through­out the day.

Dif­fer­ent genes had dif­fer­ent ac­tiv­ity pat­terns in dif­fer­ent tis­sues so the re­search team con­ser­va­tively es­ti­mate that more than half of genes would show daily fluc­tu­a­tions if ev­ery tis­sues type was sam­pled.

The liver was the most dy­namic with 3,186 genes show­ing a daily pat­tern com­pared with just 642 in the hy­po­thal­a­mus.

Two ma­jor win­dows of ac­tiv­ity were ob­served in the study - dawn and dusk. It is al­ready known that some drugs work bet­ter at cer­tain times of the day.

Heart dis­ease is driven by artery-clog­ging choles­terol, which is mostly made in the liver at night. Tak­ing statins in the evening makes them more ef­fec­tive.

The re­searchers said 56 of the top 100 sell­ing drugs and nearly half of the World Health Or­ga­ni­za­tion’s list of es­sen­tial medicines acted on genes which were now known to have this daily os­cil­la­tion.

‘Real op­por­tu­nity’

Dr John Ho­ge­nesch told the BBC News web­site: “I’m hope­ful that we can use this in­for­ma­tion to de­sign bet­ter ther­a­pies with ex­ist­ing drugs, and that’s huge be­cause it’s not go­ing to cost any more money.

“I think there is a real op­por­tu­nity to im­prove cur­rent med­i­ca­tion in a way that will be im­pact­ful.”

Dr Si­mon Archer, a body clock sci­en­tist from the Univer­sity of Sur­rey, told the BBC: “If you move away from one tis­sue, we looked at gene ex­pres­sion just in the blood, and look at the whole or­gan­ism then that pre­cise tem­po­ral or­gan­i­sa­tion ap­plies to much more than peo­ple pre­vi­ously re­alised.

“If 40-50 per­cent of genes are go­ing up and down over 24-hours and th­ese are drug tar­gets, then it’s go­ing to be im­por­tant.

“Thou­sands, mil­lions of peo­ple po­ten­tially, could ben­e­fit from tak­ing their med­i­ca­tion at a dif­fer­ent time of day and rais­ing this kind of aware­ness is im­por­tant.”


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