[Catecholamine concentration in the brain and adrenals during the ontogenesis of mammals with different levels of motor activity].

In dogs and squirrels which in natural environment reveal high level of muscle activity, the content of norepinephrine in the brain stem and total content of epinephrine and norepinephrine in the suprarenals are lower than in rabbits and albino rats which are characterized by a lower muscle activity. Differences in norepinephrine content of the brain stem between dogs and rats originally appear in the period of realization of the standing posture. At this time, norepinephrine content of the brain stem in dogs becomes maximal, decreasing on further development of animals, whereas in rats it continues to increase up to the 4th month of postnatal life. In rats which were bred from the age of 1 month under the conditions of intensive muscle exercise, norepinephrine content of the brain stem at the age of 7 months is lower than in control animals.