The experimental study is devoted to the identification of possible psychomodulatory and anxiolytic effects of ACTH(4- 7)-Pro-Gly-Pro and ACTH(6-9)-Pro-Gly-Pro under conditions of thyroid hyperfunction. Material and methods. The experiment was performed on white male rats, which were divided into groups: I – control; II – rats with hyperthyroidism model, III and IV – animals receiving ACTH(4-7)-Pro-Gly-Pro (Semax) and ACTH(6-9)-Pro-Gly-Pro at doses of 174 and 178 μg/kg/day, respectively, for 21 days against the background of hyperthyroidism. The development of experimental hyperthyroidism in animals was induced by administration of an aqueous solution of potassium iodide at a dose of 75 µg/kg by intragastric gavage, daily for 3 weeks. Behavioural activity was assessed using psychopharmacological tests “Lattice” and “Light-Dark box” in standard modification. Results and discussion. Under conditions of experimental hyperthyroidism in the “Lattice” test, changes in psychomotor behaviour of animals were observed in the form of suppression of orienteering and exploratory activity, namely, a decrease in the number of stands and exploratory “peeks” downwards. In the test “Light-Dark box” against the background of thyroid hyperfunction, an increase in the level of anxiety was observed, manifested in a decrease in the time spent in the light compartment, the number of transitions between compartments and racks, as well as an increase in the number of assessments of “risk” – “looking out” of the compartment. The studied substances ACTH(4-7)-Pro-Gly-Pro and ACTH(6-9)-Pro-Gly-Pro in conditions of experimental hyperthyroidism promoted the correction of the above-mentioned behavioural disorders, eliminating the anxiety-depressive state of laboratory animals. Conclusions. When studying the effect of ACTH(4-7)-Pro-Gly-Pro and ACTH(6-9)-Pro-Gly-Pro substances under conditions of experimental hyperthyroidism on behavioural activity of white rats in the tests “Lattice” and “Light-Dark box” it was revealed that the studied peptide compounds exhibit psychomodulatory and anxiolytic effects, correcting behavioural reactions.
