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Increases in local cerebral blood flow and acetylcholine in the hippocampus by stimulation of the septal complex in anesthetized rats
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A POSSIBLEROLE OF ADRENALINE ON RESPIRATORY RHYTHMGENERATION IN THE MEDULLAOF NEWBORNRAT IN AKIKOARATA* HIROSHIONIMARU,AND IKUO HOMMA. Department of Physiology,Showa --*--
m.
University -School of Medicine, 1-5-8 Hatanodai, ShinaRawa-ku,_Tokyo 142 Respiratory rhythm in the brainstem-spinal cord preparation isolated from newborn rat is presumably geneiateh by Pre-I neurons locaked close tb PNMT-immunoreactive (adrenaline-synthesizing) neurons in the rostra1 ventrolateral medulla. Adrenaline (AD) inhibits respiratory rhythm by inhibiting Pre-I neuron activity, mediated in part by a GABAAergic mechanism. In the present study, to investigate the direct action of AD on Pre-I neurons, we examined effects of AD on Pre-I activity under blockade of chemical synaptic transmission by incubating in low Ca (0.2 d), high Mg (5 mM) solution (referred to here as low Ca). Pre-I activity was enhanced in 17 units, depressed in 3 units, and not affected in 4 units by perfusion of l-5 JIMAD in low Ca. Pre-I activity in low Ca was enhanced by perfusion of 5 pM phenylephrine and depressed by 5 pM clonidine. In normal Ringer solution containing 5 PM bicuculline, a GABAA-antagonist, 5 pM clonidine applied to the brainstem strongly inhibited the respiratory rhythm, and S-10 pM phenylephrine enhanced the rhythm. The effect of phenylephrine was more conspicuous when the rhythm was depressed, for instance, after clonidine application. Isoproterenol (20 PM) slightly enhanced the rhythm. Pre-I activity was reversibly depressed by 5-10 pM prazosine, an al antagonist. Results suggest that direct action of AD on Pre-I neurons is excitatory via al-receptors and inhibitory via a2-receptors. We suggest that AD might intrinsically regulate respiratory rhythm by stabilizing Pre-I pacemaker activity through opposite actions mediated by al- and a2- receptors, whereas it indirectly inhibits the rhythm by activating the GABAA-system.
VASODILATIVE RESPONSE OF CORTICAL CEREBRAL BLOOD FLOW TO STIMULATION OF THE ROSTRAL YENTROLATERAL MEDULLA. YUKA SAEKI- , AK10 SATO, YUKO SATO, AND ANDRZEJ TRZEBSKI , Department of Physiology , Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173 Japan. The effect of stimulation of the rostra1 ventrolateral medulla (RVLM) on cortical cerebral blood flow (CBF) was examined by laser Doppler flowmetry in urethane-anesthetized, artificially ventilated rats. Electrical stimulation of the RVLM produced an increase in cortical CBF. The RVLM-induced cortical vasodilative response was present in animals with spinal cords sectioned at levels of Th3-4 and with bilateral extracerebral cervical sympathetic trunks severed. Chemical stimulation by microinjection of L-glutamte into the RVLM also produced an increase in cortical CBF. The RVLM-induced vasodilative response was totally but not by blockers for muscarinic, eliminated by a2 ,adrenergic bl;z;zf;;ors . It was concluded that there is an nicotinic, adrenergic al, and a intracerebral vasodilative neural pathway, including an a2 adrenergic receptor, originating in the RVLM for regulation of cortical blood vessels. Ref: Saeki, Sato, Sato, and Trzebski, Stimulation of the rostra1 ventrolateral medullary neurons increases cortical cerebral blood flow via activation of intracerebral neural pathway. Neurosci. Lett., in press.
INCREASES IN LOCAL CEREBRAL BLOOD FLOW AND ACETYLCHOLINE IN THE HIPPOCpMPUS BY WEI-HUA CA0 , OSAMU STIMULA$ION OF THE SEPTAL COMPLEX IN ANESTHETIZED RATS. INANAMI , AK10 SATO, AND YUKO SATO, Department of Physiology, Tokyo Metropolitan Institute of Gerontology 35-2 Sakaecho, Itabashiku, Tokyo 173, Japan. The effects of foci1 stimulation, either electrically or chemically, of the septal complex (i.e., the medial septal nucleus and the nucleus of the diagonal band) on the local hippocampal cerebral blood flow measured by laser Doppler Electrical stimulation of the flowmetry were examined in anesthetized rats. septal complex produced a current-dependent increase in hippocampal cerebral blood flows in dorsal hippocampus, ventral hippocampus and subiculum. This increase was accompanied by an increase in extracellular acetylcholine (ACh) release in the hippocampus. Microinjection of L-glutamate (50-100 nmol) into the septal complex also produced an increase in hippocampal cerebral blood flow. Administration of the nicotinic cholinergic blocking agent, mecamylamine (2 mg/kg, i.v.), attenuated markedly the vasodilative response elicited by L-glutamate stimulation of the septum, but not the response elicited by electrical stimulation. It was suggested that the cholinergic fibers originating in the septum and the non-cholinergic fibers passing the septum both act as intracerebral vasodilative neural systems.
A POSSIBLEROLE OF ADRENALINE ON RESPIRATORY RHYTHMGENERATION IN THE MEDULLAOF NEWBORNRAT IN AKIKOARATA* HIROSHIONIMARU,AND IKUO HOMMA. Department of Physiology,Showa --*--
m.
University -School of Medicine, 1-5-8 Hatanodai, ShinaRawa-ku,_Tokyo 142 Respiratory rhythm in the brainstem-spinal cord preparation isolated from newborn rat is presumably geneiateh by Pre-I neurons locaked close tb PNMT-immunoreactive (adrenaline-synthesizing) neurons in the rostra1 ventrolateral medulla. Adrenaline (AD) inhibits respiratory rhythm by inhibiting Pre-I neuron activity, mediated in part by a GABAAergic mechanism. In the present study, to investigate the direct action of AD on Pre-I neurons, we examined effects of AD on Pre-I activity under blockade of chemical synaptic transmission by incubating in low Ca (0.2 d), high Mg (5 mM) solution (referred to here as low Ca). Pre-I activity was enhanced in 17 units, depressed in 3 units, and not affected in 4 units by perfusion of l-5 JIMAD in low Ca. Pre-I activity in low Ca was enhanced by perfusion of 5 pM phenylephrine and depressed by 5 pM clonidine. In normal Ringer solution containing 5 PM bicuculline, a GABAA-antagonist, 5 pM clonidine applied to the brainstem strongly inhibited the respiratory rhythm, and S-10 pM phenylephrine enhanced the rhythm. The effect of phenylephrine was more conspicuous when the rhythm was depressed, for instance, after clonidine application. Isoproterenol (20 PM) slightly enhanced the rhythm. Pre-I activity was reversibly depressed by 5-10 pM prazosine, an al antagonist. Results suggest that direct action of AD on Pre-I neurons is excitatory via al-receptors and inhibitory via a2-receptors. We suggest that AD might intrinsically regulate respiratory rhythm by stabilizing Pre-I pacemaker activity through opposite actions mediated by al- and a2- receptors, whereas it indirectly inhibits the rhythm by activating the GABAA-system.
VASODILATIVE RESPONSE OF CORTICAL CEREBRAL BLOOD FLOW TO STIMULATION OF THE ROSTRAL YENTROLATERAL MEDULLA. YUKA SAEKI- , AK10 SATO, YUKO SATO, AND ANDRZEJ TRZEBSKI , Department of Physiology , Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173 Japan. The effect of stimulation of the rostra1 ventrolateral medulla (RVLM) on cortical cerebral blood flow (CBF) was examined by laser Doppler flowmetry in urethane-anesthetized, artificially ventilated rats. Electrical stimulation of the RVLM produced an increase in cortical CBF. The RVLM-induced cortical vasodilative response was present in animals with spinal cords sectioned at levels of Th3-4 and with bilateral extracerebral cervical sympathetic trunks severed. Chemical stimulation by microinjection of L-glutamte into the RVLM also produced an increase in cortical CBF. The RVLM-induced vasodilative response was totally but not by blockers for muscarinic, eliminated by a2 ,adrenergic bl;z;zf;;ors . It was concluded that there is an nicotinic, adrenergic al, and a intracerebral vasodilative neural pathway, including an a2 adrenergic receptor, originating in the RVLM for regulation of cortical blood vessels. Ref: Saeki, Sato, Sato, and Trzebski, Stimulation of the rostra1 ventrolateral medullary neurons increases cortical cerebral blood flow via activation of intracerebral neural pathway. Neurosci. Lett., in press.
INCREASES IN LOCAL CEREBRAL BLOOD FLOW AND ACETYLCHOLINE IN THE HIPPOCpMPUS BY WEI-HUA CA0 , OSAMU STIMULA$ION OF THE SEPTAL COMPLEX IN ANESTHETIZED RATS. INANAMI , AK10 SATO, AND YUKO SATO, Department of Physiology, Tokyo Metropolitan Institute of Gerontology 35-2 Sakaecho, Itabashiku, Tokyo 173, Japan. The effects of foci1 stimulation, either electrically or chemically, of the septal complex (i.e., the medial septal nucleus and the nucleus of the diagonal band) on the local hippocampal cerebral blood flow measured by laser Doppler Electrical stimulation of the flowmetry were examined in anesthetized rats. septal complex produced a current-dependent increase in hippocampal cerebral blood flows in dorsal hippocampus, ventral hippocampus and subiculum. This increase was accompanied by an increase in extracellular acetylcholine (ACh) release in the hippocampus. Microinjection of L-glutamate (50-100 nmol) into the septal complex also produced an increase in hippocampal cerebral blood flow. Administration of the nicotinic cholinergic blocking agent, mecamylamine (2 mg/kg, i.v.), attenuated markedly the vasodilative response elicited by L-glutamate stimulation of the septum, but not the response elicited by electrical stimulation. It was suggested that the cholinergic fibers originating in the septum and the non-cholinergic fibers passing the septum both act as intracerebral vasodilative neural systems.