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Distribution of glutamate-containing neurons innervating the rostral ventrolateral medulla in shr and WKY rats
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DIFFERENCE O F LONG-TERM POTENTIATION A N D P H O R B O L ESTER-INDUCED SYNAPTIC POTENTIATION IN H I P P O C A M P A L P Y R A M I D A L N E U R O N S A F T E R T R A N S I E N T ISCHEMIA. TOSHIHIRO E B I S A W A .1, HUGH P.C. R O B I N S O N .1, AKIKO M I W A t, A K I R A T A M U R A .2, T A K A A K I KIRINO *z, N O B U F U M I K A W A I t, 'Department of Neurobiology, Tokyo Metropolitan Institute for Neurosciences, 2-6 Musashidai, Fuchu City, Tokyo 183 and 2Department o f Neurosur~er¥, Teikyo University, 2-11-1, Kaga, Itabashi-ku, Tokyo 173, Japan. Slices were made from the hippocampus of gerbils, following transient ischemia produced b y clamping the carotid arteries for 5 minutes and the subsequent changes in CAI pyramidal neurons were studied electrophysiologically as well as morphologically. In a majority of C A I pyramidal neurons in slices prepared more than 24 hours after ischemia, long-term potentiation (LTP) could not be induced following tetanic stimulation of Schaffer collateral-commissural fiber input. Failure of LTP in C A I pyramidal neurons was more pronounced in areas C A I a and C A l b than in C A l c . These differences corresponded well to morphological changes due to cell degeneration. When phorbol ester, an activator of protein kinase C, was applied to slices from ischemic gerbil, CA1 pyramidal neurons which failed to elicit LTP showed a strong potentiation o f synaptic potentials. Pretreatment with tt-7, an inhibitor of protein kinase C, prevented the phorbol esterinduced synaptic potentiation. This indicates that LTP caused by tetanic stimulation is different from phorbol ester-induced synaptic potentiation in ischemic gerbils.
8. Central autonomic control SENSITIVITY DIFFERENCE IN CARDIOVASCULAR RESPONSES TO MICROINJECTION OF AfiONISTS OF GLUTAMATE RECEPTOR SUBTYPES INTO THE ROSTRAL VENTROLATERAL MEDULLA BETWEEN SHR RATS, WKY RATS AND CATS.
MITSUHIEO ~IU~A, KIYOSHIGE TAKAYAMA AND JUNICHI
OEADA.
Department o__~f
Physiolo~ylstDivision. Ounma U n i v e r s i t y School o f Medicipe, 3-3g-22 Showa-machi, Maebashi-shi. Gunma 371, Japan. We t e s t e d the h y p o t h e s i s t h a t h y p e r s e n s i t i v i t y of the r o s t r a l v e n t r o l a t e r a l medulla (RVLM) n e u r o n s in the s p o n t a n e o u s l y h y p e r t e n s i v e r a t s (SHR) to g l u t a m a t e may lead to h y p e r t e n s i o n due to h y p e r a c t i v i t y of the sympathetic n e r v e s . Wistar-Kyoto r a t s ( c o n t r o l ) , SHR r a t s and c a t s were a n e s t h e t i z e d by u r e t h a n e (60 mg/Kg) a n d / o r c h l o r a l o s e (10-60 mg/EK), and a g o n i s t s of glutamate r e c e p t o r subtypes as well as glutamate were i n j e c t e d i n t o the RVI.~. The dose-response r e l a t i o n s h i p was examined, and the s e n s i t i v i t y was e s t i m a t e d by values of the t h r e s h o l d (pmoles). Compared with the WKY r a t s , the s e n s i t i v i t y of the SHR r a t s was s i g n i f i c a n t l y d i f f e r e n t , b e i n g 10 times h i g h e r to k a i n a t e , 50 times h i g h e r to q u l s q u a l a t e , 10 times h i g h e r to NMDAand glutamate. On the o t h e r hand, the s e n s i t i v i t i e s of the c a t s was I / 5 to k a i n a t e , and 1/10 to NMDA, but a l m o s t t h e same to q u t s q u a l a t e and glutamate. AP4 had no e f f e c t on c i r c u l a t i o n . G e n e r a l l y , the s e n s i t i v i t y of RV[24 neurons to s t i m u l a n t s of glutamate r e c e p t o r s was g r e a t e r in SHR r a t s than in WKY r a t s and normotensive c a t s (P<0.001). Thus, we suggest t h a t the genesis of h y p e r t e n s i o n in the SHR r a t s may be due to abnormal p r o p e r t i e s of g l u t a m a t e r e c e p t o r s u b t y p e s a c t i n g on the RVLM n e u r o n s involved in c i r c u l a t i o n .
DISTRIBUTION OF GLUTAMATE-CONTAINING NEURONS INNERVATING THE ROSTRAL VENTROLATERAL MEDULLA IN SHR AND WKY RATS. KIYOSHIGE TAKAYAMA. AND MITSUHIKO__ MIURA. DePartment of PhvsiNo0y 1st Division. Gunma Universitv School of Medicine. 3-39-22 Show~c machi. Maebashi :~7"t, ~a~an, Recently, differences have been obse~ed in circulatory responses to stimulation of the rostral ventrolateral medulla (RVLM) of spontaneously hypertensive rats (SHR) and normotensive rats (WKY) by agonists of glutamate receptor subtypes. Thus, we examined the distribution of glutamatergic neurons projecting to the RVLM of SHR rats and WKY rats. We injected 10-30 nl of 2% WGA-HRP into the regions of the RVLM in rats anesthetized with urethane (600 mg/kg, i.p.) and cNoralose (60 mg/kg, i.p.). Neurons of the supraspinal structures were examined by both the HRP-labeling and glutamate-staining method. We found that the RVLM was innervated, with ipsilateral dominance, from the central amygdaloid nucleus, lateral hypothalamus, paraventricular nucleus, parabrachial nucleus, Koelliker-Fuse area, solitary tract nucleus and reticular formation in the medulla. In each nucleus, the percentage of double-labeled HRP neurons ranged from 5 to 20 % except for the reticular formation of medulla (26-33 % ) . No significant difference in the percentage of double labeled neurons in each nucleus was observed between SHR rats and WKY rats.
DIFFERENCE O F LONG-TERM POTENTIATION A N D P H O R B O L ESTER-INDUCED SYNAPTIC POTENTIATION IN H I P P O C A M P A L P Y R A M I D A L N E U R O N S A F T E R T R A N S I E N T ISCHEMIA. TOSHIHIRO E B I S A W A .1, HUGH P.C. R O B I N S O N .1, AKIKO M I W A t, A K I R A T A M U R A .2, T A K A A K I KIRINO *z, N O B U F U M I K A W A I t, 'Department of Neurobiology, Tokyo Metropolitan Institute for Neurosciences, 2-6 Musashidai, Fuchu City, Tokyo 183 and 2Department o f Neurosur~er¥, Teikyo University, 2-11-1, Kaga, Itabashi-ku, Tokyo 173, Japan. Slices were made from the hippocampus of gerbils, following transient ischemia produced b y clamping the carotid arteries for 5 minutes and the subsequent changes in CAI pyramidal neurons were studied electrophysiologically as well as morphologically. In a majority of C A I pyramidal neurons in slices prepared more than 24 hours after ischemia, long-term potentiation (LTP) could not be induced following tetanic stimulation of Schaffer collateral-commissural fiber input. Failure of LTP in C A I pyramidal neurons was more pronounced in areas C A I a and C A l b than in C A l c . These differences corresponded well to morphological changes due to cell degeneration. When phorbol ester, an activator of protein kinase C, was applied to slices from ischemic gerbil, CA1 pyramidal neurons which failed to elicit LTP showed a strong potentiation o f synaptic potentials. Pretreatment with tt-7, an inhibitor of protein kinase C, prevented the phorbol esterinduced synaptic potentiation. This indicates that LTP caused by tetanic stimulation is different from phorbol ester-induced synaptic potentiation in ischemic gerbils.
8. Central autonomic control SENSITIVITY DIFFERENCE IN CARDIOVASCULAR RESPONSES TO MICROINJECTION OF AfiONISTS OF GLUTAMATE RECEPTOR SUBTYPES INTO THE ROSTRAL VENTROLATERAL MEDULLA BETWEEN SHR RATS, WKY RATS AND CATS.
MITSUHIEO ~IU~A, KIYOSHIGE TAKAYAMA AND JUNICHI
OEADA.
Department o__~f
Physiolo~ylstDivision. Ounma U n i v e r s i t y School o f Medicipe, 3-3g-22 Showa-machi, Maebashi-shi. Gunma 371, Japan. We t e s t e d the h y p o t h e s i s t h a t h y p e r s e n s i t i v i t y of the r o s t r a l v e n t r o l a t e r a l medulla (RVLM) n e u r o n s in the s p o n t a n e o u s l y h y p e r t e n s i v e r a t s (SHR) to g l u t a m a t e may lead to h y p e r t e n s i o n due to h y p e r a c t i v i t y of the sympathetic n e r v e s . Wistar-Kyoto r a t s ( c o n t r o l ) , SHR r a t s and c a t s were a n e s t h e t i z e d by u r e t h a n e (60 mg/Kg) a n d / o r c h l o r a l o s e (10-60 mg/EK), and a g o n i s t s of glutamate r e c e p t o r subtypes as well as glutamate were i n j e c t e d i n t o the RVI.~. The dose-response r e l a t i o n s h i p was examined, and the s e n s i t i v i t y was e s t i m a t e d by values of the t h r e s h o l d (pmoles). Compared with the WKY r a t s , the s e n s i t i v i t y of the SHR r a t s was s i g n i f i c a n t l y d i f f e r e n t , b e i n g 10 times h i g h e r to k a i n a t e , 50 times h i g h e r to q u l s q u a l a t e , 10 times h i g h e r to NMDAand glutamate. On the o t h e r hand, the s e n s i t i v i t i e s of the c a t s was I / 5 to k a i n a t e , and 1/10 to NMDA, but a l m o s t t h e same to q u t s q u a l a t e and glutamate. AP4 had no e f f e c t on c i r c u l a t i o n . G e n e r a l l y , the s e n s i t i v i t y of RV[24 neurons to s t i m u l a n t s of glutamate r e c e p t o r s was g r e a t e r in SHR r a t s than in WKY r a t s and normotensive c a t s (P<0.001). Thus, we suggest t h a t the genesis of h y p e r t e n s i o n in the SHR r a t s may be due to abnormal p r o p e r t i e s of g l u t a m a t e r e c e p t o r s u b t y p e s a c t i n g on the RVLM n e u r o n s involved in c i r c u l a t i o n .
DISTRIBUTION OF GLUTAMATE-CONTAINING NEURONS INNERVATING THE ROSTRAL VENTROLATERAL MEDULLA IN SHR AND WKY RATS. KIYOSHIGE TAKAYAMA. AND MITSUHIKO__ MIURA. DePartment of PhvsiNo0y 1st Division. Gunma Universitv School of Medicine. 3-39-22 Show~c machi. Maebashi :~7"t, ~a~an, Recently, differences have been obse~ed in circulatory responses to stimulation of the rostral ventrolateral medulla (RVLM) of spontaneously hypertensive rats (SHR) and normotensive rats (WKY) by agonists of glutamate receptor subtypes. Thus, we examined the distribution of glutamatergic neurons projecting to the RVLM of SHR rats and WKY rats. We injected 10-30 nl of 2% WGA-HRP into the regions of the RVLM in rats anesthetized with urethane (600 mg/kg, i.p.) and cNoralose (60 mg/kg, i.p.). Neurons of the supraspinal structures were examined by both the HRP-labeling and glutamate-staining method. We found that the RVLM was innervated, with ipsilateral dominance, from the central amygdaloid nucleus, lateral hypothalamus, paraventricular nucleus, parabrachial nucleus, Koelliker-Fuse area, solitary tract nucleus and reticular formation in the medulla. In each nucleus, the percentage of double-labeled HRP neurons ranged from 5 to 20 % except for the reticular formation of medulla (26-33 % ) . No significant difference in the percentage of double labeled neurons in each nucleus was observed between SHR rats and WKY rats.