- Email: [email protected]
Homotypic serotonergic reinnervation of the hippocampus following neonatal 5,7-DHT treatment
244
Expression of phenylethanolamine-n-methyltransferasein sympathetic neurons and extraadrenal chromaffin tissue of chick embryos in vivo and in vitro. G. TeitelmanI, S. Skaper 2, H. Baker I,
D. Park 1, T.H. Joh I S. Varon 2, D~. R-eTs1, R ~ A ~ . 1Lab. of Neurobiol., Cornell Univ. Med. Col., NY, NY 10021; 2Dept. Biol. Univ. CA, San Diego; Dept. Opth., Johns Hopkins U., MD. Previous studies seemed to indicate the existence of two populations of cells in the mammalian sympathetic nervous system which differ in their ability to express phenylethanolamine-N-methyltransferase (PNMT), the enzyme which specifically subserves the biosynthesis of epinephrine: (1) sympathoblasts and their progeny, the noradrenergic sympathetic neurons (PNMT negative), and (2) phaeochromoblasts, which originate the adrenergic cells of the adrenal gland and extraadrenal chromaffin tissue (PNMT positive). We sought to determine whether similar differences between sympathoblasts and phaeochromoblasts exist in other classes of vertebrate embryos. Using immunohistochemical and biochemical techniques to assay PNMT in sympathetic organs in vivo and i_n vitr% we have found that chick embryo paravertebral ganglia contain PNMT activity both in vivo and in vitro. In vitro PNMT immunostaining was detected in principal neurons as well as in small process bearing neurons similar to mammalian SIF cells. In vivo, cells containing PNMT were seen not only in the adrenal gland, but also in other sympathetic structures such as the extraadrenal chromaffin tissue and, unexpectedly, also in some cells of the kidney. In all cases, tyrosine hydroxylase, the first enzyme of the catecholamine (CA) biosynthetic pathway, was found in the same cells which could be stained with PNMT antibodies. Thus, we conclude that in contrast to the rat, chick sympathoblasts share with phaeochromoblasts the property of expressing all the CA enzymes, including PNMT.
Homotypic Serotonergic Reinnervation of the Hippocampus Following Neonatal 5,7-DHT Treatment Towle, A.C., Mueller, R.A., Breese, G.R., Lauder, J.~. Depts. of Anatomy, Anesthesiology and Pharmacology. UNC Med. Sch., Chapel H i l l , NC 27514 Administration of 5,7-DHT (50~g, i n t r a c i s t e r n a l ) + DMI (20mg/kg i . p . ) to neonatal rats leads to a permanent loss of serotonergic c e l l s and terminals throughout the brain. Uhile few immunoreactive serotonergic f i b e r s are v i s i b l e f i v e days a f t e r treatment, w i t h i n 15 days a l i m i t e d serotonergic reinnervation of the hippocampus becomes evident. Other brain regions, including the cortex, hypothalamus and dorsal raphe nucleus, remain devoid of serotonergic neurons and terminals for at least 60 days. The serotonerqic neurons of the medial raphe nucleus, which normally innervate the hippocampus, are reduced in number by 85% f o l l o w i n g the 5,7-DHT treatment. Nevertheless, i t appears that these few c e l l s can s e l e c t i v e l y reinnervate a considerable area of the hippoca~pus. Moreover, these remaining neurons appear larger than in controls, suggesting that increased c e l l u l a r a c t i v i t y occurs during t h i s period of regeneration. !'!hen adult rats were s i m i l a r l y treated, no reinnervation of the hippocampus or a l t e r a tions in the number or size of midbrain serotonergic neurons were observed, i n d i c a t i n o that the adult serotonergic system does not respond in the same manner. Although the mechanisms underlying t h i s phenomenon are unclear i t appears that the process may i n volve regeneration of injured serotonergic neurons rather than c o l l a t e r a l sprouting or innervation of denervated t e r r i t o r y by adjacent serotonergic terminals.
Impaired cerebellar development and u n d e r l y i n g structural deficient Brattleboro rat. A morphometrieal study. van Norde, W., Uylings, H . B . M . and B o e r , G . J . , Netherlands Institute for Brain Research, Amsterdam
deficits
in
the
vasopressin
Since in homozygous diabetes insipidus vasopressin deficient Brattleboro rats (HOM-DI) especially the cerebellar weight and DNA c o n t e n t were significantly lower than those in heterozygous, vasopressin producing rats (HET-DI)(Boer et al., 1982), cerebella of HOM-DI a n d HET-DI r a t s o f 1 2 , 2 4 and 1 8 0 d a y s o f a g e w e r e a n a l y z e d morphometrieally. Overall areal measurements in mideagittal sections revealed an u n d e r d e v e l o p m e n t of the HOM-DI e e r e b e l l a r cortex, a s c o m p a r e d w i t h t h a t o f t h e HET-DI r a t , w h i c h i s m o r e p r o nounced on day 24 than either o n d a y 12 o r o n d a y 1 8 0 . E x a m i n a t i o n of individual lobules showed that each lobule was affected to a different extent, with lobule VI-d being affected most. The white matter, however, was even more strongly underdeveloped at all a g e s e x a m i n e d (22% o n d a y 2 4 ) . S e x u a l d i m o r p h i c effects were demonstrated in 180-day old animals, with males showing a more pronounced underdevelopment of white matter than females (29% and 11%, r e s p . ) . Purkinje cell (PC) c o u n t s in lobule VI i n m i d s a g i t t a l sections revealed that there is no difference i n PC n u m b e r b e t w e e n HOM-DI and HET-DI rats at any age examined. The granule cell number, however, appeared to be significantly r e d u c e d i n HOM-DI c e r e b e l l u m (as determined on day 24 post partum). The underdevelopment o f t h e w h i t e m a t t e r i n HOM-DI r a t s s u g g e s t s that oligodendroglial cells are also affected i n t h e HOM-DI c e r e b e l l u m .
Expression of phenylethanolamine-n-methyltransferasein sympathetic neurons and extraadrenal chromaffin tissue of chick embryos in vivo and in vitro. G. TeitelmanI, S. Skaper 2, H. Baker I,
D. Park 1, T.H. Joh I S. Varon 2, D~. R-eTs1, R ~ A ~ . 1Lab. of Neurobiol., Cornell Univ. Med. Col., NY, NY 10021; 2Dept. Biol. Univ. CA, San Diego; Dept. Opth., Johns Hopkins U., MD. Previous studies seemed to indicate the existence of two populations of cells in the mammalian sympathetic nervous system which differ in their ability to express phenylethanolamine-N-methyltransferase (PNMT), the enzyme which specifically subserves the biosynthesis of epinephrine: (1) sympathoblasts and their progeny, the noradrenergic sympathetic neurons (PNMT negative), and (2) phaeochromoblasts, which originate the adrenergic cells of the adrenal gland and extraadrenal chromaffin tissue (PNMT positive). We sought to determine whether similar differences between sympathoblasts and phaeochromoblasts exist in other classes of vertebrate embryos. Using immunohistochemical and biochemical techniques to assay PNMT in sympathetic organs in vivo and i_n vitr% we have found that chick embryo paravertebral ganglia contain PNMT activity both in vivo and in vitro. In vitro PNMT immunostaining was detected in principal neurons as well as in small process bearing neurons similar to mammalian SIF cells. In vivo, cells containing PNMT were seen not only in the adrenal gland, but also in other sympathetic structures such as the extraadrenal chromaffin tissue and, unexpectedly, also in some cells of the kidney. In all cases, tyrosine hydroxylase, the first enzyme of the catecholamine (CA) biosynthetic pathway, was found in the same cells which could be stained with PNMT antibodies. Thus, we conclude that in contrast to the rat, chick sympathoblasts share with phaeochromoblasts the property of expressing all the CA enzymes, including PNMT.
Homotypic Serotonergic Reinnervation of the Hippocampus Following Neonatal 5,7-DHT Treatment Towle, A.C., Mueller, R.A., Breese, G.R., Lauder, J.~. Depts. of Anatomy, Anesthesiology and Pharmacology. UNC Med. Sch., Chapel H i l l , NC 27514 Administration of 5,7-DHT (50~g, i n t r a c i s t e r n a l ) + DMI (20mg/kg i . p . ) to neonatal rats leads to a permanent loss of serotonergic c e l l s and terminals throughout the brain. Uhile few immunoreactive serotonergic f i b e r s are v i s i b l e f i v e days a f t e r treatment, w i t h i n 15 days a l i m i t e d serotonergic reinnervation of the hippocampus becomes evident. Other brain regions, including the cortex, hypothalamus and dorsal raphe nucleus, remain devoid of serotonergic neurons and terminals for at least 60 days. The serotonerqic neurons of the medial raphe nucleus, which normally innervate the hippocampus, are reduced in number by 85% f o l l o w i n g the 5,7-DHT treatment. Nevertheless, i t appears that these few c e l l s can s e l e c t i v e l y reinnervate a considerable area of the hippoca~pus. Moreover, these remaining neurons appear larger than in controls, suggesting that increased c e l l u l a r a c t i v i t y occurs during t h i s period of regeneration. !'!hen adult rats were s i m i l a r l y treated, no reinnervation of the hippocampus or a l t e r a tions in the number or size of midbrain serotonergic neurons were observed, i n d i c a t i n o that the adult serotonergic system does not respond in the same manner. Although the mechanisms underlying t h i s phenomenon are unclear i t appears that the process may i n volve regeneration of injured serotonergic neurons rather than c o l l a t e r a l sprouting or innervation of denervated t e r r i t o r y by adjacent serotonergic terminals.
Impaired cerebellar development and u n d e r l y i n g structural deficient Brattleboro rat. A morphometrieal study. van Norde, W., Uylings, H . B . M . and B o e r , G . J . , Netherlands Institute for Brain Research, Amsterdam
deficits
in
the
vasopressin
Since in homozygous diabetes insipidus vasopressin deficient Brattleboro rats (HOM-DI) especially the cerebellar weight and DNA c o n t e n t were significantly lower than those in heterozygous, vasopressin producing rats (HET-DI)(Boer et al., 1982), cerebella of HOM-DI a n d HET-DI r a t s o f 1 2 , 2 4 and 1 8 0 d a y s o f a g e w e r e a n a l y z e d morphometrieally. Overall areal measurements in mideagittal sections revealed an u n d e r d e v e l o p m e n t of the HOM-DI e e r e b e l l a r cortex, a s c o m p a r e d w i t h t h a t o f t h e HET-DI r a t , w h i c h i s m o r e p r o nounced on day 24 than either o n d a y 12 o r o n d a y 1 8 0 . E x a m i n a t i o n of individual lobules showed that each lobule was affected to a different extent, with lobule VI-d being affected most. The white matter, however, was even more strongly underdeveloped at all a g e s e x a m i n e d (22% o n d a y 2 4 ) . S e x u a l d i m o r p h i c effects were demonstrated in 180-day old animals, with males showing a more pronounced underdevelopment of white matter than females (29% and 11%, r e s p . ) . Purkinje cell (PC) c o u n t s in lobule VI i n m i d s a g i t t a l sections revealed that there is no difference i n PC n u m b e r b e t w e e n HOM-DI and HET-DI rats at any age examined. The granule cell number, however, appeared to be significantly r e d u c e d i n HOM-DI c e r e b e l l u m (as determined on day 24 post partum). The underdevelopment o f t h e w h i t e m a t t e r i n HOM-DI r a t s s u g g e s t s that oligodendroglial cells are also affected i n t h e HOM-DI c e r e b e l l u m .