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Effect of a non-NMDA antagonist on induction of long-term potentiation in kitten visual cortex
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D E'~ERHINATION OF THE ROSTROCAUDAL POLARITY OF TIIE AVIAN OPTIC TECTUH. NAKAMURA, 11!.__~ ICHIJO, H'z** MATSUNO, !*l._.,. anti ITASAKI, N * I Dept. of Biol!._.,. and Pathol~._.j. Ryoto P r e f e c t u r a l Univ. of Medicine, N i s h i t a k a t s u k a s a - c h o , Taishogun, K i t a - k u , Kyoto 603, J__a_P~n. A n a l y s i s of r o t a t i o n of the o p t i c rectum a n l a g e n through 1800 has shown t h a t the r o s t r o c a u d a l p o l a r i t y of the o p t i c rectum in b i r d s is not determined around the l O - s o m i t e s t a g e . We t r a n s p l a n t e d the caudal h a l f of the q u a i l rectum a n l a g e n i n t o the r o s t r a l h a l f of the c h i c k tectum a n l a g e n as well as r o s t r a l h a l f of the q u a i l rectum a n l a g e n i n t o the caudal h a l f of the c h i c k rectum anlagen at the 2 0 - 3 5 - s o m i t e s t a g e . P r o j e c t i o n p a t t e r n s of nasal or temporal retinal g a n g l i o n c e l l s to the c h i m e r i c tectum were a n a l y z e d u s i n g f l u o r e s c e n t dye, D i l , on ti~e 16th day of i n c u b a t i o n on whole-mount s p e c i m e n s . A f t e r o b s e r v a t i o n of the whole mount, the specimens were p r o c e s s e d f o r Feulgen s t a i n i n g to i d e n t i f y the g r a f t . Our r e s u l t s revealed t h a t ( l ) nasal r e t i n a l f i b e r s p r o j e c l e d to the caudal p a r t of the tectum (which was o r i g i n a l l y r o s t r a l ) j u s t as in the c o n t r o l when the t r a n s p l a n t a t i o n was done before 25-somite-stage, (2) n a s a l r e t i n a l f i b e r s s e n t many a r b o r s a t the caudal p a r t of the tectum (which was o r i g i n a l l y r o s t r a l ) as i l s e e k i n g a t a r g e t when the t r a n s p l a n t a t i o n was done around 2 5 - s o m i t e s t a g e , and (3) n a s a l r e t i n a l f i b e r s were d e g e n e r a t e d at the caudal p a r t of the tectum which d i f f e r e n t i a t e d from the r o s t r a l p a r t of the tectum a n l a g e a f t e r transplantation around 30 s o m i t e s t a g e . We conclude t h a t d e t e r m i n a t i o n of the r o s t r o c a u d a l p o l a r i t y of the rectum o c c u r s at around the 3 0 - s o m i t e s t a g e (3rd day of i n c u b a t i o n ) .
ROSTROCAUDALPOLARITY OF THE AVIAN TECTAL PRIMORDI~M i n v i t r o . HIROYUKI ICH_~[/_Q[~ NOBUE ~ TORU MATSUNQ~ HARUKAZU NAKAMURAa AND CHIHIRO HAMA~ Department o f PatholoF~z ~ and B i o l o g y ~ Kyoto P r e f . Univ. Med. Kyoto. N a t i o n a l I n s t i t u t e of N--~euroscience~ NCNP, Kodaira. J-~Pan. Plasticity of r o s t r o c a u d a l p o l a r i t y was r e v e a l e d in t h r e e a s p e c t s of t e c t a l development by rotation of the avian t e c t a l primordium: t a r g e t r e c o g n i t i o n of r e t i n a l g a n g l i o n c e l l s , as well as c y t o a r c h i t e c t o n i c development and e x p r e s s i o n of e n g r a i l e d p r o t e i n , along r o s t r o e a u d a l a x i s of the rectum and the t e c t a l primordium. The f i n d i n g s s u g g e s t t h a t r o s t r o c a u d a l p o l a r i t y of the t e c t a l primordium is a c q u i r e d through i n t e r a c t i o n s between the t e c t a l primordium and s u r r o u n d i n g structures. To u n d e r s t a n d , t h e i r c e l l u l a r and m o l e c u l a r mechanisms, we p r e p a r e d e x p l a n t s from certain r e g i o n s of the n e u r a l tube at the 7 - s o m i t e s t a g e of c h i c k embryo, and c u l t u r e d them on collagen gel. We o b s e r v e d the development of r o s t r o c a u d a l p o l a r i t y in e x p l a n t s u s i n g e n g r a f t e d p r o t e i n as the marker. I t was shown t h a t r o s t r o c a u d a l p o l a r i t y of e n g r a i l e d p r o t e i n e x p r e s s i o n o c c u r s in the explant i n c l u d i n g mesencephalon and m e s e n c e p h a l o - m e t e n c e p h a l i c j u n c t i o n . But e n g r a i l e d p r o t e i n is h a r d l y e x p r e s s e d in the e x p l a n t from a r o s t r a t 2/3 fragment of mesencephalon. This s u g g e s t t h a t the m e s e n c e p h a l o - m e t e n c e p h a l i c j u n c t i o n is important f o r r o s t r o c a u d a l p o l a r i t y of e n g r a i l e d p r o t e i n e x p r e s s i o n .
EFFECT OF A NON-NMDA ANTAGONIST ON INDUCTION OF LONG-TERM POTENTIATION 1N KITTEN VISUAL CORTEX. YUKIO KOMATSU AND HICHIYO IWAKIRI, Department of Physiologyu_Kyoto P r e f e c t u r a l U n i v e r s i t z of Hedicine, Kawaramachi-Hirokoji, Kamigyoku, Kyoto 602, J a p a n . Our previous study demonstrated t h a t long-term p o t e n t i a t i o n {LTP) could be induced under the blockade of N-methyl-D-aspartate (NMDA) r e c e p t o r s in the k i t t e n v i s u a l c o r t e x . In the p r e s e n t study, the involvement of non-NHDA r e c e p t o r s in the induction of LTP was t e s t e d in s l i c e s prepared f r o m k i t t e n s aged 30-40 days. Two s t i m u l a t i n g e l e c t r o d e s , s l and s2, w e r e placed in each side of the white matter s e p a r a t e d at its c e n t e r . The field potentials evoked by the electrodes were r e c o r d e d from l a y e r II-III. T e s t s t i m u l a t i o n was a p p l i e d a l t e r n a t i v e l y to sl a n d s2 at an i n t e r v a l of I0 s. The s] was u s e d to t e s t the e f f e c t of c o n d i t i o n i n g stimulation and s2 to c o n f i r m that a non-NMDA antagonist DNQX w a s w a s h e d out c o m p l e t e l y . A f t e r the r e s p o n s e s w e r e a l m o s t a b o l i s h e d by b a t h a p p l i c a t i o n of D N Q X (20 pH), conditioning stimulation was (2 Hz, 15 m i n u t e s ) a p p l i e d to s}, d u r i n g w h i c h p e r i o d Hg z' was r e m o v e d from the p e r f u s a t e to f a c i l i t a t e N H D A t r a n s m i s s i o n . A f t e r the c o n d i t i o n i n g s t i m u l a t i o n , D N Q X was w a s h e d out. The r e s p o n s e s e v o k e d by s2 r e c o v e r e d to the c o n t r o l level ( I 0 6 ~ 6 % of c o n t r o l , n=9l a b o u t 2 h o u r s a f t e r the c o n d i t i o n i n g stimulation, while t h o s e by sl d i d not (88±6%l. T h e s e r e s u l t s i n d i c a t e that the L T P requires activation of the n o n - N H D A r e c e p t o r s but not of the N H D A r e c e p t o r s d u r i n g c o n d i t i o n i n g s t i m u l a t i o n .
D E'~ERHINATION OF THE ROSTROCAUDAL POLARITY OF TIIE AVIAN OPTIC TECTUH. NAKAMURA, 11!.__~ ICHIJO, H'z** MATSUNO, !*l._.,. anti ITASAKI, N * I Dept. of Biol!._.,. and Pathol~._.j. Ryoto P r e f e c t u r a l Univ. of Medicine, N i s h i t a k a t s u k a s a - c h o , Taishogun, K i t a - k u , Kyoto 603, J__a_P~n. A n a l y s i s of r o t a t i o n of the o p t i c rectum a n l a g e n through 1800 has shown t h a t the r o s t r o c a u d a l p o l a r i t y of the o p t i c rectum in b i r d s is not determined around the l O - s o m i t e s t a g e . We t r a n s p l a n t e d the caudal h a l f of the q u a i l rectum a n l a g e n i n t o the r o s t r a l h a l f of the c h i c k tectum a n l a g e n as well as r o s t r a l h a l f of the q u a i l rectum a n l a g e n i n t o the caudal h a l f of the c h i c k rectum anlagen at the 2 0 - 3 5 - s o m i t e s t a g e . P r o j e c t i o n p a t t e r n s of nasal or temporal retinal g a n g l i o n c e l l s to the c h i m e r i c tectum were a n a l y z e d u s i n g f l u o r e s c e n t dye, D i l , on ti~e 16th day of i n c u b a t i o n on whole-mount s p e c i m e n s . A f t e r o b s e r v a t i o n of the whole mount, the specimens were p r o c e s s e d f o r Feulgen s t a i n i n g to i d e n t i f y the g r a f t . Our r e s u l t s revealed t h a t ( l ) nasal r e t i n a l f i b e r s p r o j e c l e d to the caudal p a r t of the tectum (which was o r i g i n a l l y r o s t r a l ) j u s t as in the c o n t r o l when the t r a n s p l a n t a t i o n was done before 25-somite-stage, (2) n a s a l r e t i n a l f i b e r s s e n t many a r b o r s a t the caudal p a r t of the tectum (which was o r i g i n a l l y r o s t r a l ) as i l s e e k i n g a t a r g e t when the t r a n s p l a n t a t i o n was done around 2 5 - s o m i t e s t a g e , and (3) n a s a l r e t i n a l f i b e r s were d e g e n e r a t e d at the caudal p a r t of the tectum which d i f f e r e n t i a t e d from the r o s t r a l p a r t of the tectum a n l a g e a f t e r transplantation around 30 s o m i t e s t a g e . We conclude t h a t d e t e r m i n a t i o n of the r o s t r o c a u d a l p o l a r i t y of the rectum o c c u r s at around the 3 0 - s o m i t e s t a g e (3rd day of i n c u b a t i o n ) .
ROSTROCAUDALPOLARITY OF THE AVIAN TECTAL PRIMORDI~M i n v i t r o . HIROYUKI ICH_~[/_Q[~ NOBUE ~ TORU MATSUNQ~ HARUKAZU NAKAMURAa AND CHIHIRO HAMA~ Department o f PatholoF~z ~ and B i o l o g y ~ Kyoto P r e f . Univ. Med. Kyoto. N a t i o n a l I n s t i t u t e of N--~euroscience~ NCNP, Kodaira. J-~Pan. Plasticity of r o s t r o c a u d a l p o l a r i t y was r e v e a l e d in t h r e e a s p e c t s of t e c t a l development by rotation of the avian t e c t a l primordium: t a r g e t r e c o g n i t i o n of r e t i n a l g a n g l i o n c e l l s , as well as c y t o a r c h i t e c t o n i c development and e x p r e s s i o n of e n g r a i l e d p r o t e i n , along r o s t r o e a u d a l a x i s of the rectum and the t e c t a l primordium. The f i n d i n g s s u g g e s t t h a t r o s t r o c a u d a l p o l a r i t y of the t e c t a l primordium is a c q u i r e d through i n t e r a c t i o n s between the t e c t a l primordium and s u r r o u n d i n g structures. To u n d e r s t a n d , t h e i r c e l l u l a r and m o l e c u l a r mechanisms, we p r e p a r e d e x p l a n t s from certain r e g i o n s of the n e u r a l tube at the 7 - s o m i t e s t a g e of c h i c k embryo, and c u l t u r e d them on collagen gel. We o b s e r v e d the development of r o s t r o c a u d a l p o l a r i t y in e x p l a n t s u s i n g e n g r a f t e d p r o t e i n as the marker. I t was shown t h a t r o s t r o c a u d a l p o l a r i t y of e n g r a i l e d p r o t e i n e x p r e s s i o n o c c u r s in the explant i n c l u d i n g mesencephalon and m e s e n c e p h a l o - m e t e n c e p h a l i c j u n c t i o n . But e n g r a i l e d p r o t e i n is h a r d l y e x p r e s s e d in the e x p l a n t from a r o s t r a t 2/3 fragment of mesencephalon. This s u g g e s t t h a t the m e s e n c e p h a l o - m e t e n c e p h a l i c j u n c t i o n is important f o r r o s t r o c a u d a l p o l a r i t y of e n g r a i l e d p r o t e i n e x p r e s s i o n .
EFFECT OF A NON-NMDA ANTAGONIST ON INDUCTION OF LONG-TERM POTENTIATION 1N KITTEN VISUAL CORTEX. YUKIO KOMATSU AND HICHIYO IWAKIRI, Department of Physiologyu_Kyoto P r e f e c t u r a l U n i v e r s i t z of Hedicine, Kawaramachi-Hirokoji, Kamigyoku, Kyoto 602, J a p a n . Our previous study demonstrated t h a t long-term p o t e n t i a t i o n {LTP) could be induced under the blockade of N-methyl-D-aspartate (NMDA) r e c e p t o r s in the k i t t e n v i s u a l c o r t e x . In the p r e s e n t study, the involvement of non-NHDA r e c e p t o r s in the induction of LTP was t e s t e d in s l i c e s prepared f r o m k i t t e n s aged 30-40 days. Two s t i m u l a t i n g e l e c t r o d e s , s l and s2, w e r e placed in each side of the white matter s e p a r a t e d at its c e n t e r . The field potentials evoked by the electrodes were r e c o r d e d from l a y e r II-III. T e s t s t i m u l a t i o n was a p p l i e d a l t e r n a t i v e l y to sl a n d s2 at an i n t e r v a l of I0 s. The s] was u s e d to t e s t the e f f e c t of c o n d i t i o n i n g stimulation and s2 to c o n f i r m that a non-NMDA antagonist DNQX w a s w a s h e d out c o m p l e t e l y . A f t e r the r e s p o n s e s w e r e a l m o s t a b o l i s h e d by b a t h a p p l i c a t i o n of D N Q X (20 pH), conditioning stimulation was (2 Hz, 15 m i n u t e s ) a p p l i e d to s}, d u r i n g w h i c h p e r i o d Hg z' was r e m o v e d from the p e r f u s a t e to f a c i l i t a t e N H D A t r a n s m i s s i o n . A f t e r the c o n d i t i o n i n g s t i m u l a t i o n , D N Q X was w a s h e d out. The r e s p o n s e s e v o k e d by s2 r e c o v e r e d to the c o n t r o l level ( I 0 6 ~ 6 % of c o n t r o l , n=9l a b o u t 2 h o u r s a f t e r the c o n d i t i o n i n g stimulation, while t h o s e by sl d i d not (88±6%l. T h e s e r e s u l t s i n d i c a t e that the L T P requires activation of the n o n - N H D A r e c e p t o r s but not of the N H D A r e c e p t o r s d u r i n g c o n d i t i o n i n g s t i m u l a t i o n .