At the 1st, 2nd and 3rd days after birth, subcutaneous injections of 6-oxydopamine in physiological solution containing 0.1% of ascorbic acid have been made to rat puppies in a dose 100 mg/kg per one injection. Within first three weeks, electromyographic studies were made on outbursts of autogenic periodic motor activity which is typical of animals at this age. It was shown that at the 3rd day of postnatal life, after 6-oxydopamine administration, total duration of motor excitation is significantly lower, whereas mean duration of the outbursts of continuous activity is lower even at the 7th day. Beginning from the 10th day, these parameters undergo opposite changes at the background of the increase in the number of outbursts and the decrease of intervals between the latter. The data obtained are discussed in relation to the role of catecholaminergic systems in regulation and realization of age dynamics of autogenic motor activity.

Aging↗

PubMedDate not supplied

[The formation of activity-rest cycles in early ontogeny].

The cyclic variations of the motor activity consist of many rhythmic components which appear nonsimultaneously in the ontogenesis. The earliest component is the autogenic periodic motility with the duration about one minute which can be observed in rats during first two-three weeks after the birth. From the second week a new type of cyclic activity appears. It can be qualified as a sleep-wakefulness cycle with the duration about several minutes. It is suggested that this cycle is a true novel rhythm which is able to modulate the earliest more frequent periodicity.

Aging↗

PubMedDate not supplied

[The role of the dopamine and noradrenaline systems in regulating autogenic motor activity in rat pups].

In experiments on 3-day rat puppies, studies have been made of the effect of a stimulator of noradrenaline receptors--clonidine, and a stimulator of dopamine receptors--apomorphine on autogenic motor activity. It was shown that clonidine injections result in a significant increase of this activity, whereas apomorphine slightly decreases the latter. The data obtained in the present work together with those described earlier for l-DOPA effects, suggest that double regulation of autogenic activity is realized at early stages of ontogenesis. This regulation includes excitatory noradrenergic mechanisms and inhibitory influences which are mediated presumably by dopaminergic systems of the brain.

Animals↗

PubMedDate not supplied

[Role of catecholaminergic mechanisms in regulating the autogenic periodic motor activity of rat pups].

In 1-, 2- to 3-, 7- to 8-, and 10-day old intact and spinal rat puppies, studies have been made of the effect of l-DOPA (100 mg/kg, intraperitoneally) on autogenic periodic motor activity in the gastrocnemius muscle. In 1- to 3-day old pups, strong stimulating effect was observed up to a prolonged continuous activity for 5-10 or even more minutes. This effect decreases with age. Traces of the inhibitory effect are observed at early stages in the form of total decrease of the activity. The inhibitory effect increases with age. In all spinal animals, at the background of a decreased activity, stimulating effect of l-DOPA was predominantly observed. Age peculiarities of the effect of l-DOPA are discussed in relation to ontogenetic development of catecholaminergic innervation in rats. It is suggested that stimulating effect of l-DOPA is associated with its action on the descending noradrenergic system, whereas the inhibitory one is mediated by the brain structures.

Aging↗

PubMedDate not supplied

[The action of L-DOPA on the structure of spontaneous motor activity in rat pups].

In experiments on 2-3-, 7-8-, 10- and 16-day old rat pups, basic age differences have been observed in the effect of a precursor of catecholamine mediator, i.e. L-DOPA on the activity on the spinal and brain mechanisms of autogenic periodic motor excitation. Strong stimulation of the spinal motor rhythm was observed during the first week. At this period, supraspinal rhythm becomes even less evident. On further development, the effect is an opposite one. In 10- and 16-day rat pups, at the background of total inhibition of the spontaneous activity, administration of L-DOPA significantly increases the activity of supraspinal generator of the motor rhythm. The data obtained reveal ontogenetic changes in regulatory mechanisms of autogenic motor activity.

Aging↗

PubMedDate not supplied

[Characteristics of autogenic motor stimulation in rat pups].

Studies have been made on the organization of the spontaneous motor activity during first 2 weeks of postnatal life of rats Rattus norvegicus (var albin.) by means of prolonged EMG recording from the gastrocnemius muscle and by computer analysis. Complexes of prolonged activity with a period of about 1 min, intracomplex periodicity of short pulses with a frequency 1/sec and periodicity of separate short bursts arranged into series with intervals between them of approximately 8-12 sec were observed. It was found that the main rhythm of these forms of excitation remains relatively unchanged during postnatal ontogenesis. The number of periods filled by series of short bursts decreases in postnatal development of animals, whereas the number of periods of a complete rest lasting for 1 1/2 and more minutes increases. These findings were compared with the development of sleep--wakefulness cycle in early postnatal ontogenesis.

Aging↗

PubMedDate not supplied

[Effect of haloperidol on late long-term discharges induced by stimulation of the flexor reflex afferents in rat offsprings of early age].

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Afferent Pathways↗