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Enhancement of acetylcholine release in the insular gustatory cortex of rats in response to aversive taste stimulation
S226
2006
THE ORIGIN OF AFFERENTS TO THE LATERAL HABENULAR NUCLEUS IN THE RAT DEMONSTRATED BY A FLUORESCENT RETROGRADE LABELLING METHOD WITH FLUOROGOLD. TINGYU QU, KAI DONG, HANIE A. RAHMAN, KOSHI YAMADA, TAKASHI YAMADORI. 1st. Dept.of Anat,Kobe Univ.Sch. of Med.. 7-5-1, Kusunoki-cho. Chuo-ku, Kobe. 650, Japan. Iontophoretic injection of fluorescent dye, Fluoro-Gold (FG), confined to the lateral habenular nucleus (LHB) unilaterally in the rat, demonstrated the existence of labeled cells in various regions of the forebrain and brain stem. Generally, the results were similar to those reports using different methods. FG-labeled cells were observed in other regions, for which horseradish peroxidase (HRP) tracing data are not available, including the ipsilateral medial preoptic area, arcuate nucleus and suprachiasmatic nucleus. FG labeled axons were observed in the ipsilateral fasciculus retroflexus (fr) as well as in the habenular commissure (hbc). The present study showed the possibility that Fluoro-Gold may be transported either anterogradely or retrogradely.
2007
SOMATIC, VISCERAL AND GUSTATORY INPUTS TO THE INSULAR CORTEX OF THE RATS. TAKAMITSU HANAMORI, TAKATO KUNITAKE, KAZUHIDE HIROTA AND HIROSHI KANNAN. 1st. Dept. of Physiol., Miyazaki Med. Coil.. Mivazaki, 889-16,Jaoan
Extracellular unit responses to tail pinch, gustatory stimulation of the posterior tongue, baro- and chemoreceptor stimulation, and electrical stimulation of the superior laryngeal (SL) nerve were recorded from the insular cortex of the anesthetized and paralyzed rats with glass microelectrodes. Of the 24 neurons which had responded to electrical stimulation of the SL nerve, 21 showed an excitatory or inhibitory response to at least one of the stimuli (tail pinch, gustatory, baro- and chemoreceptor) and 3 had no response. Of the 24 neurons, 8 were excited by tail pinch, 6 were inhibited, and the remaining 10 had no response. Most neurons (20/24) showed an excitatory or inhibitory response to intravenous application of at least one of the drugs (methoxamine hydrochloride, nitroprusside and sodium cyanide). On the contrary, a few neurons (7124) were sensitive to gustatory stimulation (NaCl, HCl, QHCl, sucrose) of the vallate and foliate papillae. These results indicate that visceral, gustatory and nociceptive afferents project to the insular cortex and that insular cortex neurons receive convergent inputs from different kind of sensory organs.
2008
ENHANCEMENT OF ACETYLCHOLINE RELEASE IN THE INSULAR GUSTATORY CORTEX OF RATS IN RESPONSE TO AVERSIVE TASTE STIMULATION. TSUYOSHI SHIMURA AND TAKASHI YAMAMOTO, Dept. of Behav. Phvsiol., Fat. of Human Sci., Osaka Univ., l-2 Yamadaoka, Suita. Osaka, 565,Japan.
Recent neurochemical evidence has suggested that acetylcholine (ACh) acts as a neurotransmitter in the insular gustatory cortex (GC) of rats (Lopez-Garcia et al., 1990). In an attempt to elucidate a possible role of ACh in processing of taste, we measured the release of ACh in the GC of freely moving rats using the microdialysis technique. At least 4 h before each experiment, a microdialysis probe (2.0 mm in membrane length and 0.5 mm in diameter) was implanted in the GC via the guide cannula. The probe was perfused at a flow rate of 2 pl/min with artificial cerebtospinal fhtid. Four hours a&r the probe implantation, each animal received a 10 ml intraoral it&ion of fluids for 10 min. Samples were collected at 20-min intervals and dialysates were analyzed by high-performance liquid chromatography with electrochemical detection. The mean basal release of ACh before stimulation was 273 + 21 fmoI/ 10 p.l (mean + SE, n=25). Intraoral infusions of various taste stimuli or distilled water significantly increased the release of ACh. Infusions of 0.001 M quinine HCI produced a marked increase in the release of ACh up to 355% of baseline. Infusions of 0.01 M saccharin to the subjects that had acquired an aversion to this taste also caused a prominent increase in ACh up to 343% of baseline. In contrast, saccharin infusion to the naive subjects moderately increased ACh level up to 243% of baseline. These results suggest that ACh release in the insular gustatory cortex is related to behavioral expression to aversive taste stimuli.
2006
THE ORIGIN OF AFFERENTS TO THE LATERAL HABENULAR NUCLEUS IN THE RAT DEMONSTRATED BY A FLUORESCENT RETROGRADE LABELLING METHOD WITH FLUOROGOLD. TINGYU QU, KAI DONG, HANIE A. RAHMAN, KOSHI YAMADA, TAKASHI YAMADORI. 1st. Dept.of Anat,Kobe Univ.Sch. of Med.. 7-5-1, Kusunoki-cho. Chuo-ku, Kobe. 650, Japan. Iontophoretic injection of fluorescent dye, Fluoro-Gold (FG), confined to the lateral habenular nucleus (LHB) unilaterally in the rat, demonstrated the existence of labeled cells in various regions of the forebrain and brain stem. Generally, the results were similar to those reports using different methods. FG-labeled cells were observed in other regions, for which horseradish peroxidase (HRP) tracing data are not available, including the ipsilateral medial preoptic area, arcuate nucleus and suprachiasmatic nucleus. FG labeled axons were observed in the ipsilateral fasciculus retroflexus (fr) as well as in the habenular commissure (hbc). The present study showed the possibility that Fluoro-Gold may be transported either anterogradely or retrogradely.
2007
SOMATIC, VISCERAL AND GUSTATORY INPUTS TO THE INSULAR CORTEX OF THE RATS. TAKAMITSU HANAMORI, TAKATO KUNITAKE, KAZUHIDE HIROTA AND HIROSHI KANNAN. 1st. Dept. of Physiol., Miyazaki Med. Coil.. Mivazaki, 889-16,Jaoan
Extracellular unit responses to tail pinch, gustatory stimulation of the posterior tongue, baro- and chemoreceptor stimulation, and electrical stimulation of the superior laryngeal (SL) nerve were recorded from the insular cortex of the anesthetized and paralyzed rats with glass microelectrodes. Of the 24 neurons which had responded to electrical stimulation of the SL nerve, 21 showed an excitatory or inhibitory response to at least one of the stimuli (tail pinch, gustatory, baro- and chemoreceptor) and 3 had no response. Of the 24 neurons, 8 were excited by tail pinch, 6 were inhibited, and the remaining 10 had no response. Most neurons (20/24) showed an excitatory or inhibitory response to intravenous application of at least one of the drugs (methoxamine hydrochloride, nitroprusside and sodium cyanide). On the contrary, a few neurons (7124) were sensitive to gustatory stimulation (NaCl, HCl, QHCl, sucrose) of the vallate and foliate papillae. These results indicate that visceral, gustatory and nociceptive afferents project to the insular cortex and that insular cortex neurons receive convergent inputs from different kind of sensory organs.
2008
ENHANCEMENT OF ACETYLCHOLINE RELEASE IN THE INSULAR GUSTATORY CORTEX OF RATS IN RESPONSE TO AVERSIVE TASTE STIMULATION. TSUYOSHI SHIMURA AND TAKASHI YAMAMOTO, Dept. of Behav. Phvsiol., Fat. of Human Sci., Osaka Univ., l-2 Yamadaoka, Suita. Osaka, 565,Japan.
Recent neurochemical evidence has suggested that acetylcholine (ACh) acts as a neurotransmitter in the insular gustatory cortex (GC) of rats (Lopez-Garcia et al., 1990). In an attempt to elucidate a possible role of ACh in processing of taste, we measured the release of ACh in the GC of freely moving rats using the microdialysis technique. At least 4 h before each experiment, a microdialysis probe (2.0 mm in membrane length and 0.5 mm in diameter) was implanted in the GC via the guide cannula. The probe was perfused at a flow rate of 2 pl/min with artificial cerebtospinal fhtid. Four hours a&r the probe implantation, each animal received a 10 ml intraoral it&ion of fluids for 10 min. Samples were collected at 20-min intervals and dialysates were analyzed by high-performance liquid chromatography with electrochemical detection. The mean basal release of ACh before stimulation was 273 + 21 fmoI/ 10 p.l (mean + SE, n=25). Intraoral infusions of various taste stimuli or distilled water significantly increased the release of ACh. Infusions of 0.001 M quinine HCI produced a marked increase in the release of ACh up to 355% of baseline. Infusions of 0.01 M saccharin to the subjects that had acquired an aversion to this taste also caused a prominent increase in ACh up to 343% of baseline. In contrast, saccharin infusion to the naive subjects moderately increased ACh level up to 243% of baseline. These results suggest that ACh release in the insular gustatory cortex is related to behavioral expression to aversive taste stimuli.