[Influence of electrical stimulation of "hunger center" of the lateral hypothalamus and food reinforcements on myoelectrical activity of the gastro-esophageal sphincter and stomach in rabbits under the conditions of hunger and satiation].

AIM

To study the combined effect of electrostimulation of "hunger center" of the lateral hypothalamus (LH) and food-obtaining behavior arising from it on myoelectrical activity of gastro-esophageal sphincter (GES) and the stomach in pre-fed and subjected to food deprivation animals . MATERIAL AND METHODS. Registration of myoelectrical GES and the stomach activity was carried out under free-behavior conditions in rabbits subjected to food deprivation or pre-fed before the experiment. It was done by means of chronically implanted electrodes during LH electrostimulation in the presence of food. Simultaneously using the web-camera the animals behavior was recorded. LH stimulation was produced by STM-100C stimulator (USA) with implanted bipolar nichrome electrodes. Analysis of temporal parameters of myoelectrical activity of GES and the stomach were carried out by the program AcqKnowledge (USA), and statistical analysis of the data by the program Statistica 6. Significanse of differences between the samples was assessed by the U-Mann-Whitney test (p < 0.05).

RESULTS

Electrostimulation of "hunger center" of the lateral hypothalamus in pre-fed rabbits and the rabbits subjected to daily food deprivation, in the presence of food causes resultant food behavior which is accompanied by regular generations of bursts of peak potentials, frequency of which is essentially different in hungry and satiated animals and depends on intensity of artificially induced and artificially reinforced food motivation. In the process of LH stimulation arising resultant food behavior in satiated animals is accompanied by regular generation of high-amplitude slow electrical waves (SEW) by the muscles of lesser curvature (LC), the body and antrum of the stomach (AS) and this is reflected in the structure of temporal organization of slow electrical activity (SEA) in the form of monomodal distributions of SEW periods, typical of satiation state. Despite the increase in food motivation level, due to LH stimulation, additional entry of food into the stomach of satiated rabbits completely eliminates inhibitory effect of starvational motivational excitation on SEA of the muscles of LC, the body and AS. SEA alterations of the stomach muscles in hungry rabbits in the presence of food and thus arising of food-obtaining behavior during LH stimulation have two-phase character. At the initial stage of food behavior in hungry animals during LH stimulation high extent of scaterring of the values of SEW periods generated by the body and AS muscles is preserved, as evidenced by the bimodal distribution of SEW periods characteristic of the state of hunger. In spite of food entry into the stomach at the 1-st phase of LH stimulation, inhibitory effect of artificially reinforced starvational motivational excitation on pacemaker activity of the stomach is retained. At the 2-nd phase of LH electrostimulation food reinforcement eliminates inhibitory effect of food motivational excitation on myoelectrical activity of pacemaker of the stomach that gives maximal rhythm of SEW generation to the body and AS, monomodal distributions of SEW periods indicate to it.

CONCLUSION

lnteraction of artificially induced and artificially reinforced food motivational excitation with afferentation from food reinforcement on neurons of the central generator of deglutition pattern and dorsal vagal complex due to LH electrostimulation and thereby arising resultant food obtaining behavior is specifically reflected in patterns of myoelectrical activity of GES, LC, the body and AS.