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Excitatory effect of adenosine A1 and A2 receptor agonists and antagonists on neurotransmission in the superior colliculus slices
2-10
EFFECTS OF VESTIBULAR
STIMULATION
ON HISTAMINE
RELEASE
FROM THE
HYPOTHALAMUS AND ACETYLCHOLINE RELEASE FROM THE HIPPOCAMPUS IN RATS. ARATA HORII, NORIAKI TAKEDA. TOW MATSUNAGA. ATSUSHI YAMATODANI’. TAKATOSHI MOCHIZUKI**. KAORI OKAKURA-MOCHIZUKI”. AND YUMIKO YAMAMOTO*. Deot. of Otolarvnaol., *Mol. Phvsiol.. **Pharmacol.ll, Osaka Univ. Med. Sch.. Fukushima-ku, Osaka. 553. Jaoan Histamine (HA) HI-blocker and acetylcholine (Ach) muscarinic antagonist are effective in preventing motion sickness. From these findings, the histaminergic and cholinergic neuron systems are likely to be influenced by vestibular inputs. To examine possible interaction between the two systems, we investigated the effects of electrical vestibular stimulation through the round window of the ear on HA release from the hypothalamus and on Ach release from the hippocampus of urethane anesthetized rats using a brain microdialysis method in vim. Electrical vestibular stimulation (1 Hz, 200msec, 500& increased the release of HA and Ach to about 180%,160% of the basal release, respectively. lntraperitoneal administration of pyrilamine (5mg/kg) did not attenuate the evoked Ach release, suggesting that cholinergic neurons were not activated through l-hreceptors. Scopolamine (0.5mg/kg, i.p.) did not affect HA release evoked by the electrical vestibular stimulation, suggesting that HA release was not enhanced through muscarinic Ach receptors. Histaminergic and cholinergic neurons are independently activated by the vestibular stimulation.
2-11
EFFECT OF ADENOSINE A and A RECEPTOR AGONISTS AND ANTAGONISTS ON NEUROTRANSMISSION'IN THE'SUPERIOR COLLICULUS SLICES. AKIHIRO ISHIKAWA, EIJI KURIHARA AND YASUHIRO OKADA, Department of Physiology, School of Medicine, Kobe University, Chuo-ku, Kobe 650, Japan EXCITATORY
Adenosine (AD) is considered an inhibitory neurpmodulator in CNS. However AD has only excitatory effect on neurotransmission in the superior colliculus. To investigate the involvement of A or A adenosine receptor for the excitatory and2A agonists and antagonists were tested action of AD in SC, the effects of for neurotransmission in SC. aptic sotential (PSP) was recorded in the superficial gray layer of the guinea pig superior olli ulus slices after stimulation to the optic layer. Application of AD (10-'-10 -%) in the perfusion medium enhanced gradually the amplitude of PSP which plateayed _t9 150% of the original level in 20 min. In the similar manner R-PIA (10 -10 M), an active Al agonist enhanced thg am@itude of PSP.whe§eas_y-PIA, an inactive Al agonist did not. Both CHA (10 ,lO M) and NbCA (30 -10 M), Al agonists also showed excitatory effect._7CGS2&680 (10 -10 M), an A agonis$,had_glso excitatory effect. 8-CPT (10 410- M), A1 antagonist and &MPX (10 -10 M), an A2 antagonist enhanced the amplitude of PSP. Thus both Al and A2 receptors are to be involved in the excitatory effect in the SC slices.
SEROTONIN TRANSPORTER mRNA: DENSE EXPRESSION IN THE RAPHE NUCLEI OF THE RAT. MASAHIRO FUJITA’ .*, SHOICHI SHIMADA’, HIROSHI MAENO’, TSUNEHIKO AND MASAYA TOHYAMA’, Department of Anatomy & Neurosciencel, Department NISHIMURA* of Tracer Kinetics, Biomedical Research Centeri, Osaka University Medical School, ‘2-2 Yamadaoka, Suita, Osaka 565, Japan
2-12
Serotonin transporters terminate serotonergic neurotransmission by reuptake of exam ined was released serotonin. Expression of serotonin transporter mRNA in the rat brain by in situ hybridization histochemistry with specific oligonucleotide probe designed based Nature 1991). Serotonin serotonin transporter cDNA (Blakely, R.D., et. al., on rat From rostra1 transporter mRNA were strongly expressed in the neurons of the raphe nuclei. nucleus, median raphe to caudal level, neurons in the caudal linear nucleus, dorsal raphe raphe pallidus nucleus and raphe nucleus, raphe magnus nucleus, raphe pontis nucleus, obscurus nucleus expressed serotonin transporter mRNA. Of those nuclei, labeled neurons were contains and other nuclei rich in the dorsal raphe nucleus and raphe obscurus nucleus situated moderate or small number of labeled neurons. In addition to those positive neurons region within the confines of the raphe nuclei, strongly labeled neurons were found in the dorsal to the medial lemniscus. This distribution of the neurons containing serotonin neurons. These findings immunoreactive transporter mRNA coincides with that of serotonin and localized in pre-synaptic serotonergic suggest that this transporter is neuron-type neurons.
EFFECTS OF VESTIBULAR
STIMULATION
ON HISTAMINE
RELEASE
FROM THE
HYPOTHALAMUS AND ACETYLCHOLINE RELEASE FROM THE HIPPOCAMPUS IN RATS. ARATA HORII, NORIAKI TAKEDA. TOW MATSUNAGA. ATSUSHI YAMATODANI’. TAKATOSHI MOCHIZUKI**. KAORI OKAKURA-MOCHIZUKI”. AND YUMIKO YAMAMOTO*. Deot. of Otolarvnaol., *Mol. Phvsiol.. **Pharmacol.ll, Osaka Univ. Med. Sch.. Fukushima-ku, Osaka. 553. Jaoan Histamine (HA) HI-blocker and acetylcholine (Ach) muscarinic antagonist are effective in preventing motion sickness. From these findings, the histaminergic and cholinergic neuron systems are likely to be influenced by vestibular inputs. To examine possible interaction between the two systems, we investigated the effects of electrical vestibular stimulation through the round window of the ear on HA release from the hypothalamus and on Ach release from the hippocampus of urethane anesthetized rats using a brain microdialysis method in vim. Electrical vestibular stimulation (1 Hz, 200msec, 500& increased the release of HA and Ach to about 180%,160% of the basal release, respectively. lntraperitoneal administration of pyrilamine (5mg/kg) did not attenuate the evoked Ach release, suggesting that cholinergic neurons were not activated through l-hreceptors. Scopolamine (0.5mg/kg, i.p.) did not affect HA release evoked by the electrical vestibular stimulation, suggesting that HA release was not enhanced through muscarinic Ach receptors. Histaminergic and cholinergic neurons are independently activated by the vestibular stimulation.
2-11
EFFECT OF ADENOSINE A and A RECEPTOR AGONISTS AND ANTAGONISTS ON NEUROTRANSMISSION'IN THE'SUPERIOR COLLICULUS SLICES. AKIHIRO ISHIKAWA, EIJI KURIHARA AND YASUHIRO OKADA, Department of Physiology, School of Medicine, Kobe University, Chuo-ku, Kobe 650, Japan EXCITATORY
Adenosine (AD) is considered an inhibitory neurpmodulator in CNS. However AD has only excitatory effect on neurotransmission in the superior colliculus. To investigate the involvement of A or A adenosine receptor for the excitatory and2A agonists and antagonists were tested action of AD in SC, the effects of for neurotransmission in SC. aptic sotential (PSP) was recorded in the superficial gray layer of the guinea pig superior olli ulus slices after stimulation to the optic layer. Application of AD (10-'-10 -%) in the perfusion medium enhanced gradually the amplitude of PSP which plateayed _t9 150% of the original level in 20 min. In the similar manner R-PIA (10 -10 M), an active Al agonist enhanced thg am@itude of PSP.whe§eas_y-PIA, an inactive Al agonist did not. Both CHA (10 ,lO M) and NbCA (30 -10 M), Al agonists also showed excitatory effect._7CGS2&680 (10 -10 M), an A agonis$,had_glso excitatory effect. 8-CPT (10 410- M), A1 antagonist and &MPX (10 -10 M), an A2 antagonist enhanced the amplitude of PSP. Thus both Al and A2 receptors are to be involved in the excitatory effect in the SC slices.
SEROTONIN TRANSPORTER mRNA: DENSE EXPRESSION IN THE RAPHE NUCLEI OF THE RAT. MASAHIRO FUJITA’ .*, SHOICHI SHIMADA’, HIROSHI MAENO’, TSUNEHIKO AND MASAYA TOHYAMA’, Department of Anatomy & Neurosciencel, Department NISHIMURA* of Tracer Kinetics, Biomedical Research Centeri, Osaka University Medical School, ‘2-2 Yamadaoka, Suita, Osaka 565, Japan
2-12
Serotonin transporters terminate serotonergic neurotransmission by reuptake of exam ined was released serotonin. Expression of serotonin transporter mRNA in the rat brain by in situ hybridization histochemistry with specific oligonucleotide probe designed based Nature 1991). Serotonin serotonin transporter cDNA (Blakely, R.D., et. al., on rat From rostra1 transporter mRNA were strongly expressed in the neurons of the raphe nuclei. nucleus, median raphe to caudal level, neurons in the caudal linear nucleus, dorsal raphe raphe pallidus nucleus and raphe nucleus, raphe magnus nucleus, raphe pontis nucleus, obscurus nucleus expressed serotonin transporter mRNA. Of those nuclei, labeled neurons were contains and other nuclei rich in the dorsal raphe nucleus and raphe obscurus nucleus situated moderate or small number of labeled neurons. In addition to those positive neurons region within the confines of the raphe nuclei, strongly labeled neurons were found in the dorsal to the medial lemniscus. This distribution of the neurons containing serotonin neurons. These findings immunoreactive transporter mRNA coincides with that of serotonin and localized in pre-synaptic serotonergic suggest that this transporter is neuron-type neurons.