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Biomedical subjects

I Hernádi

Publications and source records attributed to I Hernádi.

7 recordsLinked to original sources
PubMed2000

Alterations of conditioned taste aversion after microiontophoretically applied neurotoxins in the medial prefrontal cortex of the rat.

The prefrontal cortex (PFC) has been reported to be essential in neural control of feeding. In the present study, we aimed to provide a complex characterization of behavioral consequences of PFC microlesions in CFY rats. Kainic acid (KA) was microiontophoretically applied into the mediodorsal division of PFC to damage intrinsic neurons, whereas in another group of rats, 6-hydroxydopamine (6-OHDA) was microiontophoretized into the same region to destroy catecholaminergic (CA) projection fiber terminals. Body weights, food and fluid intake of both lesioned and (sham-operated or intact) control animals were daily measured. Effects of intracellular dehydration and water deprivation were also studied. Open field activity, stereotyped behaviors, and orientation towards visual and somesthetic stimuli were pre- and postoperatively tested. To examine hypothesized consequences of mPFC microlesions on central taste information processing, the acquisition and retention of saccharine conditioned taste aversion (CTA) were studied. No major changes were recorded in body weights, food and water consumption. Dehydration or deprivation similarly increased water intake in all animals. Scores of open field activity and stereotyped behaviors in the 6-OHDA group were significantly higher than those of the other groups. As the main findings of the present studies, both KA and 6-OHDA lesioned rats displayed significant deficits in CTA acquisition and retention tests. These results suggest that the medial PFC has a substantial role in both the formation and the retrieval of CTA. Furthermore, the present findings also indicate the general significance of prefrontal CA mechanisms in the organization of goal-directed, adaptive behaviors.

Animals↗
PubMed1999

Bombesin injection into the central amygdala influences feeding behavior in the rat.

The present study was performed to determine whether low doses (10 or 40 ng) of bombesin microinjected into the amygdala could modify solid food intake. Forty ng of bombesin in 24 h deprived rats caused transient inhibition of food intake. This inhibitory effect was eliminated by prior bombesin antagonist treatment. A series of quantitative behavioral tests indicated that low doses of bombesin application specifically reduced food intake without altering the behavioral pattern or influencing the body temperature. The present results suggest, that bombesin-like peptides may act as a satiety signal in the central part of the amygdala.

Amygdala↗
PubMed1995

Role of forebrain glucose-monitoring neurons in the central control of feeding: I. Behavioral properties and neurotransmitter sensitivities.

Extracellular single neuron recording experiments were performed in the lateral hypothalamic area (LHA), amygdaloid body (AMY) and globus pallidus (GP) of anesthetized rats and anesthetized or alert rhesus monkeys during microelectrophoretic administration of different neurochemicals including glucose. Neuron activity in the behaving primate was also investigated during a conditioned bar press alimentary task, as well as during presentation of food and non-food objects. In the LHA, AMY and GP specific glucose-sensitive (GS) neurons were found, as their activity were suppressed by glucose. The proportion of GS neurons was approximately 29%, 11% and 14%, respectively. The GS neurons in the monkey were especially likely to respond to phase of the conditioned alimentary task, and these same neurons appeared to be particularly influenced by sensorimotor and motivational factors. LHA, AMY and GP GS neurons displayed distinct sensitivities to various neurotransmitters applied microelectrophoretically. The present results, along with previous data, indicate that a hirearchically organized network of the brainstem and forebrain glucose-monitoring neurons exit and this system is involved in the regulation of feeding.

Amygdala↗
PubMed1995

Role of forebrain glucose-monitoring neurons in the central control of feeding: II. Complex functional attributes.

Our parallel investigations in the lateral hypothalamic are (LHA), amygdaloid body (AMY) and globus pallidus (GP) provided evidence for the existence of glucose-sensitive (GS) neurons in these forebrain regions. To examine exogenous chemosensory responsiveness of these cells, extracellular single neuron activity was recorded in anesthetized or alert rhesus monkeys and in anesthetized rats during 1) microelectrophoretic administration of chemicals and 2) gustatory and 3) olfactory stimulations. The GS cells in all three forebrain structures were more likely than the glucose-insensitive (GIS) neurons to change in firing rate in response to tastes and smells. The gustatory (and olfactory) GS neurons, compared to the non-gustatory GS or both types of GIS cells, displayed significantly higher sensitivities to catecholamines. Neurons with both "endogenous" and "exogenous" chemosensitivity were found to be topographically organized in the LHA, AMY and GP as well. While receiving further evidence for the substantial morphological and functional overlapping of the brain's glucose-monitoring neural network and the central gustatory representations, on the basis of the present and previous findings, it is suggested that constituents of this complex system accomplish a simultaneous monitoring, integration and control of a broad variety of feeding-associated signals of the internal and external milieux for the biological welfare of the organism.

Action Potentials↗