Stress on worms could give in­sight into hu­man brain de­vel­op­ment

Iran Daily - - Health -

Worms and hu­mans might have more in com­mon neu­ro­log­i­cally than re­searchers ever thought, par­tic­u­larly when it comes to stress.

A re­cent study from the Na­tional In­sti­tute of Health put male worms un­der duress dur­ing their pu­berty to study how that stress af­fected their neu­ro­log­i­cal wiring, in­ter­estin­gengi­neer­ing.com wrote.

They dis­cov­ered stress from de­vel­op­men­tal trauma plays a role in how neu­rons func­tion.

Oliver Hobert, PHD, pro­fes­sor of bi­o­log­i­cal sciences at Columbia Univer­sity in New York City, said, “We found that en­vi­ron­men­tal stress can per­ma­nently and pro­foundly im­pact the con­nec­tiv­ity of a de­vel­op­ing ner­vous sys­tem.”

Hol­bert served as a se­nior au­thor of the study pub­lished in Na­ture.

Hobert and grad­u­ate stu­dent Emily Bayer stud­ied the ner­vous sys­tems of Caenorhab­di­tis el­e­gans, or C. el­e­gan worms. Hobert’s lab is fa­mil­iar with the tiny see-through worms; pre­vi­ous re­search teams with Hobert’s lab showed how sex­ual mat­u­ra­tion in worms could re­shape their neu­ral cir­cuits in male worms. This new re­search looked at the op­po­site ef­fect. Grad­u­ate stu­dent Emily Bayer dis­cov­ered that ex­po­sure to stress — namely star­va­tion — be­fore hit­ting sex­ual ma­tu­rity in­ter­rupts the brain’s wiring pro­cesses. Bayer also sug­gested in her re­search that it’s con­trolled in part by sero­tonin, a neu­ro­trans­mit­ter most hu­mans as­so­ciate with de­pres­sion.

“I was to­tally sur­prised. In fact, I never thought stress­ing the worms out would mat­ter,” said Bayer. “It wasn’t un­til I saw dif­fer­ences in their cir­cuits that I re­al­ized that stress could remap their wiring di­a­grams.”

Bayer said the ex­per­i­ment was slightly ac­ci­den­tal. She left sev­eral of the an­i­mals unat­tended for a few weeks. This led to the worms to com­pletely pause in their de­vel­op­men­tal state and en­ter some­thing called the ‘dauer state’.

“Ba­si­cally, if im­ma­ture worms sense stress of any kind they can tem­po­rar­ily halt their nor­mal growth for months and then restart it when the stress passes. This tem­po­rary freeze in the growth process is the dauer state,” said Hobert.

Bayer put the worms back in their nor­mal en­vi­ron­ment and they grew to full adult­hood. But she no­ticed some­thing un­usual as she ob­served their ner­vous sys­tems.

Typ­i­cally, the neu­ronal con­nec­tions in a male’s tail go away dur­ing sex­ual mat­u­ra­tion in a process called ‘prun­ing’. How­ever, Bayer no­ticed that un­fin­ished con­nec­tions in the stressed worms were still there. She also no­ticed that prun­ing is con­trolled by the op­po­site ef­fects of both sero­tonin and oc­topamine — the ‘fight or flight’ neu­ro­trans­mit­ter.

Stressed worms had prob­lems mat­ing; they spent less time in con­tact with the her­maph­ro­dite worms than the ma­ture males.

HOBERT LAB, COLUMBIA UNIVER­SITY, NY.

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