title: Age-dependent emergence of caffeine-assisted voltage oscillations in the endopiriform nucleus of rats.
abstract: The gustatory insular cortex (IC) is connected with not only the somatosensory cortex, but also the endopiriform nucleus (EPN). We have previously revealed that low-frequency electrical stimulation to the IC can elicit membrane potential oscillations at a frequency of 8-10 Hz in the somatosensory cortex of rat brain slices under bath-application of caffeine. Using the same procedure, we investigated whether the EPN has the ability to generate oscillations, and whether such oscillations emerge age-dependently. Electrical stimulations were delivered to the IC, and field potentials were recorded from the EPN. In the case of slices made from mature rats, stable field potential oscillations at 8-10 Hz were induced in the EPN after repetitive stimulations. Optical recordings revealed that signals traveled from the IC to the EPN by way of the claustrum. Generation of oscillations was N-methyl-d-aspartate (NMDA) receptor activity-dependent, since oscillatory phases disappeared following application of NMDA receptor antagonist. In slices from immature rats, however, oscillations were not induced. IC stimulation can thus age-dependently elicit membrane potential oscillations in the EPN, and the EPN oscillations were NMDA receptor activity-dependent. These findings suggest that developmental changes in properties of the EPN might contribute to development of information integration, including gustatory information.
authors.affiliation: Department of Molecular Oral Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto, Tokushima 770-8504, Japan. hyoshimu@tokushima-u.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yoshimura
authors.forename: Tokio
authors.initials: T
authors.lastname: Sugai
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Chenjuan
authors.initials: C
authors.lastname: Yao
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Akamatsu
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kato
mesh_terms: D000375:Aging; D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000502:physiology*; D004558:Electric Stimulation; D008564:Membrane Potentials / Q000187:drug effects; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine