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Immunohistochemical study of the central monoaminergic neuron systems of the postnatal young rat
S107
21 Neurotransmitters II Monoamines: Morphology and distribution I~NOHISTOCHEMICAL
STUDY OF THE CENTRAL MONOAMINERGIC NEURON SYSTEMS OF THE
POSTNATAL YOUNG RAT }~SAMI YOSHIDA , NOBUYUKI KARASAWA , MASAKO ITO , }~SAO SAKAI NAGATSU,
and IKUKO
Department of Anatomy, School of Medicine, Fujita-Gakuen Health
University, Toyoake, Aichi 470-11, Japan. Central monoaminergic neurons of the young (i, 3 and 7 weeks postnatal) rats were examined by the peroxidase-antiperoxidase method using antibodies to tyrosine hydroxylase (TH) and serotonin (5-HT).
Localization of TH- or 5-HT-
immunoreactive soma of monoaminergie neurons in the postnatal brain was mostly similar to that of adult rats.
In early postnatal (I and 3 weeks) stages,
however, a small numbers of TH-immunoreaetive neurons were found in the nucleus amygdaloideus centralis.
These TH-positive neurons were of bipolar or
aultipolar shape with small oval perikarya, and were not observed after 7 ~eeks.
There was no marked change in the features of TH-positive terminals
throughout all stages, but a remarkable difference was seen in the shape of axons forming ascending or descending tracts.
At 1 week of the postnatal
stage, compared with latter stages, fine axons bearing numerous varicosities ~ere characteristically found in the eatecholaminergic bundles such as the nedial forebrain bundle, internal capsule and dorsal tegnental bundle. tHE D I F F E R E N T I A L O B S E R V A T I O N O F T Y P E A A N D B M A O - C O N T A I N I N G t E R M I N A L F I B E R S IN T H E C E R E B R A L C O R T E X OF T H E R A T T O S H I H I R O M A E D A , R Y O H A C H I A R A I * and H I R O S H I K I M U R A D e p a r t m e n t of A n a t o m y , S h i g a U n i v e r s i t y o f M e d i c a l ~eta, Otsu, J a p a n .
Science,
Light and electron microscopic o b s e r v a t i o n of n e u r o n a l ~ l e m e n t s s h o w i n g m o n o a m i n e o x i d a s e (MAO) a c t i v i t y w a s c a r r i e d 3ut u s i n g the c o u p l e d p e r o x i d a t i o n m e t h o d c o m b i n e d w i t h p r e t r e a t m e n t of s e l e c t i v e i n h i b i t o r s , c l o r g y l i n e a n d d e p r e n y l to type A a n d B of the e n z y m e , r e s p e c t i v e l y . B a s e d on d i f f e r e n c e s in m o r p h o l o g i c a l f e a t u r e of the s y n a p s e s , two t y p e s of t e r m i n a l s w e r e i d e n t i f i e d in M A O - A c o D t a i n i n g f i b e r s : One w a s a fine v a r i c o s e f i b e r w h i c h m a d e a s y n a p t i c c o n t a c t , h a r d l y s h o w i n g a s p e c i f i c s t r u c t u r e s u c h as membrane thickening, and disappearing a f t e r l e s i o n of the m e d i a l f o r e b r a i n b u n d l e . T h e o t h e r w a s an o r d i n a r y t e r m i n a l s h o w i n g a t y p i c a l a s y m m e t r i c s y n a p s e , u s u a l l y s e e n in the d e e p layer, a n d a f f e c t e d by l e s i o n l a t e r a l to the m e d i a n n u c l e i of the t h a l a m u s but n o t b y c a u d a l lesion. T h e r e f o r e , it w a s c o n c l u d e d t h a t M A O A f i b e r s in the c e r e b r a l c o r t e x r e p r e s e n t n o r a d r e n e r g i c input o r i g i n a t i n g f r o m the l o c u s c o e r u l e u s a n d a p a r t of t h a l a m o c o r t i c a l d i f f u s e p r o j e c t i o n w h o s e t r a n s m i t t e r is y e t u n k n o w n . O n the o t h e r hand, M A O - B c o n t a i n i n g f i b e r s c o n s i s t e d of serotonergic and histaminergic n e u r o n s o r i g i n a t i n g f r o m the d o r s a l r a p h e n u c l e u s and f r o m the p o s t e r i o r h y p o t h a l a m i c m a g n o zellular neurons, respectively.
21 Neurotransmitters II Monoamines: Morphology and distribution I~NOHISTOCHEMICAL
STUDY OF THE CENTRAL MONOAMINERGIC NEURON SYSTEMS OF THE
POSTNATAL YOUNG RAT }~SAMI YOSHIDA , NOBUYUKI KARASAWA , MASAKO ITO , }~SAO SAKAI NAGATSU,
and IKUKO
Department of Anatomy, School of Medicine, Fujita-Gakuen Health
University, Toyoake, Aichi 470-11, Japan. Central monoaminergic neurons of the young (i, 3 and 7 weeks postnatal) rats were examined by the peroxidase-antiperoxidase method using antibodies to tyrosine hydroxylase (TH) and serotonin (5-HT).
Localization of TH- or 5-HT-
immunoreactive soma of monoaminergie neurons in the postnatal brain was mostly similar to that of adult rats.
In early postnatal (I and 3 weeks) stages,
however, a small numbers of TH-immunoreaetive neurons were found in the nucleus amygdaloideus centralis.
These TH-positive neurons were of bipolar or
aultipolar shape with small oval perikarya, and were not observed after 7 ~eeks.
There was no marked change in the features of TH-positive terminals
throughout all stages, but a remarkable difference was seen in the shape of axons forming ascending or descending tracts.
At 1 week of the postnatal
stage, compared with latter stages, fine axons bearing numerous varicosities ~ere characteristically found in the eatecholaminergic bundles such as the nedial forebrain bundle, internal capsule and dorsal tegnental bundle. tHE D I F F E R E N T I A L O B S E R V A T I O N O F T Y P E A A N D B M A O - C O N T A I N I N G t E R M I N A L F I B E R S IN T H E C E R E B R A L C O R T E X OF T H E R A T T O S H I H I R O M A E D A , R Y O H A C H I A R A I * and H I R O S H I K I M U R A D e p a r t m e n t of A n a t o m y , S h i g a U n i v e r s i t y o f M e d i c a l ~eta, Otsu, J a p a n .
Science,
Light and electron microscopic o b s e r v a t i o n of n e u r o n a l ~ l e m e n t s s h o w i n g m o n o a m i n e o x i d a s e (MAO) a c t i v i t y w a s c a r r i e d 3ut u s i n g the c o u p l e d p e r o x i d a t i o n m e t h o d c o m b i n e d w i t h p r e t r e a t m e n t of s e l e c t i v e i n h i b i t o r s , c l o r g y l i n e a n d d e p r e n y l to type A a n d B of the e n z y m e , r e s p e c t i v e l y . B a s e d on d i f f e r e n c e s in m o r p h o l o g i c a l f e a t u r e of the s y n a p s e s , two t y p e s of t e r m i n a l s w e r e i d e n t i f i e d in M A O - A c o D t a i n i n g f i b e r s : One w a s a fine v a r i c o s e f i b e r w h i c h m a d e a s y n a p t i c c o n t a c t , h a r d l y s h o w i n g a s p e c i f i c s t r u c t u r e s u c h as membrane thickening, and disappearing a f t e r l e s i o n of the m e d i a l f o r e b r a i n b u n d l e . T h e o t h e r w a s an o r d i n a r y t e r m i n a l s h o w i n g a t y p i c a l a s y m m e t r i c s y n a p s e , u s u a l l y s e e n in the d e e p layer, a n d a f f e c t e d by l e s i o n l a t e r a l to the m e d i a n n u c l e i of the t h a l a m u s but n o t b y c a u d a l lesion. T h e r e f o r e , it w a s c o n c l u d e d t h a t M A O A f i b e r s in the c e r e b r a l c o r t e x r e p r e s e n t n o r a d r e n e r g i c input o r i g i n a t i n g f r o m the l o c u s c o e r u l e u s a n d a p a r t of t h a l a m o c o r t i c a l d i f f u s e p r o j e c t i o n w h o s e t r a n s m i t t e r is y e t u n k n o w n . O n the o t h e r hand, M A O - B c o n t a i n i n g f i b e r s c o n s i s t e d of serotonergic and histaminergic n e u r o n s o r i g i n a t i n g f r o m the d o r s a l r a p h e n u c l e u s and f r o m the p o s t e r i o r h y p o t h a l a m i c m a g n o zellular neurons, respectively.