Cardiac, respiratory, and motor activity in norm and after activation of catecholaminergic systems in newborn rat pups

• Published in: Journal of evolutionary biochemistry and physiology Vol. 48; no. 4; pp. 430 - 444
• Main Authors: Kuznetsov, S. V., Dmitrieva, L. E., Sizonov, V. A.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01-07-2012; Springer Nature B.V
• Subjects: Animal Physiology; Antagonists; Biochemistry; Biomedical and Life Sciences; Birth; Bradycardia; Catecholamines; Comparative and Ontogenic Physiology; Developmental biology; Dopamine; Dopamine D1 receptors; Dopamine D2 receptors; Evolutionary Biology; Heart; Heart rate; Levodopa; Life Sciences; monoamines; Motor activity; Neonates; Nervous system; Neurons; Norepinephrine; Parasympathetic nervous system; Respiration; Rodents; dopamine receptors; isoamine; SCH-23390; L-DOPA; early ontogenesis; respiration; heart rhythm; suspired; motor activity
• ISSN: 0022-0930; 1608-3202
• DOI: 10.1134/S002209301204007X

Study of parameters of the cardiac, respiratory, and motor activity (MA) was carried out on newborn rat pups for the first day after birth (P0) and at the 14th day of postnatal development (P14) after change of the activity levels of dopaminergic and noradrenergic systems. To provide an excessive level of catecholamines, the animals were administered individually with L-DOPA (25–100 mg/kg) and with the indirect adrenomimetic isoamine (3 and 10 mg/kg). Additionally there were studied effects of L-DOPA and isoamine after blockade of D1 and D2 dopamine receptors (antagonists SCH-23390 and sulpirid). The L-DOPA administration produced a dose-dependent MA enhancement with its subsequent possible conversion into the continuous generalized activity. At P0 the release of monoamines was accompanied by development of weak bradycardia. There was noted a tendency for acceleration of respiration at administration of the low dose both of L-DOPA and of isoamine and for its deceleration at high doses. At P14 the L-DOPA administration was accompanied by deceleration of the heart rate (HR) by 8% and by acceleration of respiration rate (RR) by 26%. The isoamine administration produced an insignificant decrease of HR and an increase of RR by 8% at the low dose and by 21% at the high dose of the agent. At the blockade of D1 receptors, RR remained close to the background values, while at the blockade of D2 receptors it decreased insignificantly. Blockade of D1 and D2 receptors did not cause significant HR changes. Analysis of the HR variability has shown that both after L-DOPA administration and at blockade of dopamine receptors no unidirectional reaction was observed: in 80% of rat pups the portion of nerve mechanisms of HR regulation increased, while in the rest-of sympathetic and humoral factors at a decrease of parasympathetic effects. In all rat pups the isoamine administration was accompanied by a shift of the specter power into the higher frequency area; in 60% of the animals there were enhanced sympathetic effects. At P14 in rat pups after administration both of L-DOPA and of isoamine, the sympathetic nervous effects were predominant. Thus, at P0 both at release of endogenous catecholamines and at their excessive concentration in rat pups there occurs a qualitative change of character of the catecholaminergic effects on functional activity of excitable structures, particularly of those connected with regulation of respiration.