Activation of Neurons of the Medullary Centers of the Autonomic Nervous System Related to Motivated Operant Movements Realized by Rats |
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Authors: | O V Vlasenko T V Buzyka V A Maiskii A I Pilyavskii A V Maznychenko |
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Institution: | 1.Pirogov Vinnitsa National Medical University, Ministry of Public Health of Ukraine,Vinnitsa,Ukraine;2.Mechnikov Odessa National University,Odessa,Ukraine;3.Bogomolets Institute of Physiology,National Academy of Sciences of Ukraine,Kyiv,Ukraine |
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Abstract: | Using the corresponding techniques, we visualized Fos-immunoreactive (Fos-ir) and NADPH diaphorasereactive (NADPH-dr) neurons
in the medullary centers of the autonomic nervous system (ANS) of rats, which performed repetitive operant movements (catching
of food globules from the manger by the left forelimb under conditions of high food motivation). Animals were trained to perform
operant movements in 30 min-long everyday sessions during 12 days. The duration of a single food-procuring movement was about
600 msec. Realization of the operant reflex was accompanied by clearly expressed motivational/affective reactions. The heart
rate (HR) in the course of each operant movement sharply dropped (on the 10th day of training, by 12%, on average) with subsequent
recovery of this parameter within 3–4 sec. In the course of 30-min-long training sessions, the mean HR gradually decreased
(in the examined group, 7%, on average) within an interval from the 5th to the 20th min with subsequent recovery until the
end of the training session. The mean numbers of Fos-ir neurons in the medullary nuclei of the ANS (Sol, IRt, CVL, RVL, Amb, 10, and MdD) of rats performing food-procuring movements (n = 4) were significantly (P < 0.05) greater than those in the control, and the intensities of c-fos expression in these structures corresponded to the following succession: Sol > IRt > CVL+RVL/CVL > RVL. Large Fos-ir neurons were observed in the dorsal motor nucleus of the n. vagus (10) and in the Amb/RAmb nuclei. In a considerable proportion of neurons of the Sol and single cells of the 10 and Amb, we observed double labeling (Fos-ir + NADPH-dr). Thus, operant food-procuring movements are accompanied by episodes of bradycardia
related to each separate realization; in addition, a long-lasting tonic decrease in the HR developed. These autonomic reactions
are mediated by the abovementioned medullary ANS nuclei. It is supposed that the respective weakening of inhibitory sympathetic
effects on spindle receptors of the muscles involved in realization of the above operant movements can provide facilitation
of generation of proprioceptive impulsation, facilitation of monosynaptic spinal reflexes, and, finally, an increase in the
efficacy of targeted limb movements directed toward food procurement. |
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Keywords: | |
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