Neurohormoni u stresu kod insekata

Abstract

The neurohormones are the master regulators of all life processes in insects and they create a strategy of stress protecting events. Neurohormones are synthesized mainly in insect brain neurosecretory neurons. Various stressors of different intensity cause specific changes which influence on neurosecretory neurons activity and synthesis of neurohormones (biogene amines, ecdysiotropins, ecdysiostatins, allatoregulatory neurohormones, adipokinetic neurohormones, etc.). Biogene amines in insects may function as neurohormones controlling carbohydrate and lipid metabolism as the primary response of the insects to the effect of stressors. Intermediary metabolism in insects is mainly regulated by adipokinetic hormones which supply organism by energy especially in extreme conditions. Stress induces changes in release of ecdysioregulatory and allatoregulatory neurohormones and modificates ecdysones and juvenile hormones synthesis in prothoracic gland and corpora allata. The involvement of hormones of an ecdysteroid or JH type in response to stress creates the danger of an untimely induction of morphogenetic process in target cells. Limiting the quantity of secreted hormones and shortening the period when target cells are sensitive to morphogenetic stimuli removes this danger.

Neurohormoni regulišu sve životne procese insekata i kreiraju strategiju odgovora organizma na delovanje stresora. Neurohormoni se u najvećoj meri sintetišu u neurosekretnim neuronima protocerebralnog regiona mozga insekata. Stresori različitih osobina i intenziteta specifično menjaju aktivnost neurosekretnih neurona i sintezu neurohormona (biogenih amina, egdizotropina, egdizostatina, alatoregulatornih neurohormona, adipokinetičkih neurohormona itd.). Biogeni amini imaju ulogu u kontroli metabolizma ugljenih hidrata i lipida u početnim fazama stresnog odgovora insekata. Intermedijerni metabolizam je regulisan dobrim delom adipokinetičkim neurohormonima koji učestvuju u obezbeđivanju dovoljne količine energije koja je potrebna za prevazilaženje ekstremnih uslova. Stres izaziva promene u lučenju egdizoregulatornih i alatoregulatornih neurohormona i modifikuje intenzitet sinteze egdizona i juvenilnih hormona u protorakalnoj žlezdi i corpora allata. Promene u količini egdizona i juvenilnog hormona u stresu povećavaju rizik početka vremenski neadekvatnih morfogenetskih promena u tkivima insekata. Stresom izazvane promene u količini morfogenetskih neurohormona su ograničene a i periodi osetljivosti ćelija na morfogenetske stimuluse se menjaju u stresu ograničavajući donekle mogućnost neadekvatnih morfogenetskih promena.