Effects of electrical and chemical stimulation of the amygdala on the spontaneous discharge in the insular cortex in rats.
Both the amygdala (especially, the basolateral nucleus of the amygdala) and the insular cortex are important for conditioned taste aversion. From the anatomical view point, there are reciprocal connections between the insular cortex and the amygdala. In the present study, we investigated the effect of electrical and chemical stimulation of the amygdala on the spontaneous discharge of the insular cortex neurons in anesthetized rats. In most neurons (10 of 14), spontaneous discharge was decreased after a microinjection of glutamate (Glu). In these neurons, the injection site was within the basolateral nucleus of the amygdala (the basolateral/lateral nuclei). On the other hand, when a gamma amino-butyric acid (GABA) was microinjected into the basolateral nucleus of the amygdala, none of the 5 neurons showed any change in spontaneous discharge. Electrical train stimulation of the basolateral nucleus of the amygdala (100 Hz, 2-6 s) depressed the spontaneous discharge of the neurons in the insular cortex, as in the case of a Glu microinjection. These results indicate that activation of the basolateral nucleus of the amygdala could depress the neuronal activity in the insular cortex. Such results may yield data leading to the elucidation of the neuronal mechanisms of conditioned taste aversion.
Hanamori
Takamitsu
T
Department of Integrative Physiology, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake-cho, Miyazaki 889-1692, Japan. thanamo@med.miyazaki-u.ac.jp
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D018683:Excitatory Amino Acid Agents / Q000008:administration & dosage; D018682:GABA Agents / Q000008:administration & dosage; D018698:Glutamic Acid / Q000008:administration & dosage; D008297:Male; D008839:Microelectrodes; D008845:Microinjections; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010296:Parietal Lobe / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013702:Temporal Lobe / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage
D018683:Excitatory Amino Acid Agents; D018682:GABA Agents; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid