Vasopressin: a necessary factor for normal brain development?

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The development of afferents to the opossum cerebellum. Bishop, G.A., Laxson, Ho, R.H. and King, J.S. Department of Anatomy and Neuroscience Research Laboratory, The Ohio State University, Columbus, Ohio 43210

L.C.

The development of selected cerebellar afferents was studied in pouch young opossums using two methods: i) Sternberger's PAP technique for the localization of serotonin; and 2) retrograde transport of horseradish peroxidase (HRP). Serotonin (5HT) immunoreactive elements are present in the rostral cerebellum on postnatal day (PD) i. Between PD 9 and PD 17 there is a sparse, but uniform distribution of 5HT positive elements in all regions of the developing cerebellum. After PD 30 there is a gradual shift in the distribution of 5HT elements until PD 37 when the adult pattern is achieved. In the adult, 5HT has its most extensive distribution in caudal vermal folia and the paraflocculus. HRP was placed on the cerebellum beginning on PD i0. At this age afferents from the contralateral inferior olive (IO) have reached the cerebellum. A bilateral projection from the basilar pons (BP) as well as from nuclei located dorsal to the pons is present by PD 16. These data suggest that 5HT axons are present in the cerebellum prior to the arrival of efferents from the IO and BP. In addition efferents from these precerebellar nuclei reach the cerebellum before their target cells have migrated and matured to form the distinctive layers characteristic of the adult cerebellum (Laxson and King, '83). (Supported by NS 08798).

Vasopressin: a necessary f a c t o r f o r normal brain development? Boer, G.J., Netherlands I n s t i t u t e for Brain Research, I J d i j k 28, 1095 KJ Amsterdam, The Netherlands. The classical neurotransmitters have shown to be important factors in the normal development of the central nervous system of r a t . A new class of neurotransmitters appeared now to e x i s t , i . e . , the neuropeptides. Because they are early present in the growing b r a i n , a role of these neuropeptides in the ontogeny of the nervous system might be p l a u s i b l e . This the more so, since perinatal treatment with several neuropeptides a f f e c t central functions in a permanent way. The congenital absence of the neuropeptide vasopressin (VP) in the nervous system of homozygous (HOM) Brattleboro rats coexist with a stunted development of the brain, leading to permanent d e f i c i t s in brain weight and cell content, e s p e c i a l l y in the cereb e l l a r part. VP supplementation in adulthood or in the f i r s t postnatal month did n o t r e store these impairments. When given p o s t n a t a l l y the highest dosages however introduceda permanently enhanced d i u r e s i s . Prenatal a p p l i c a t i o n via continuous release of VP from a subcutane implanted Accurel d e l i v e r y device in the pregnant HOM r a t , resulted in bigger brains and heavier cerebelli containing more c e l l s , f o r the HOM o f f s p r i n g one month a f t e r b i r t h . I t is therefore concluded that VP is a f a c t o r involved in e a r l y brain development of rat.

Normal p r o l i f e r a t i o n rate of jimpy galactocerebroside p o s i t i v e oligodendrocytes in culture Bologa L. and Herschkowitz N. Department of P e d i a t r i c s , U n i v e r s i t y of Berne, 3010 Berne, Switzerland P r o l i f e r a t i o n of oligodendrocytes from the jimpy hypomyelinated mouse mutant was studied in dissociated brain c e l l c u l t u r e s . This was done by combining a n t i galactocerebroside immunostaining ( f o r i d e n t i f y i n g oligodendrocytes) with 3H-Thymidine autoradiography ( f o r i d e n t i f y i n g p r o l i f e r a t i n g c e l l s ) . Previously we showed that expression of galactocerebroside in c u l t u r e by jimpy oligodendrocytes is not altered by the jimpy mutation. Present r e s u l t s show t h a t in 7, 14 and 21-day-old jimpy cultures galactocerebroside p o s i t i v e oligodendrocytes p r o l i f e r a t e at a rate s i m i l a r to that of normal galactocerebroside p o s i t i v e oligodendrocytes. This i n d i cates t h a t , in jimpy brain c e l l c u l t u r e s , oligodendrocytes which are not affected by mutation in t h e i r c a p a b i l i t y to express galactocerebroside are also unaffected with regard to t h e i r p r o l i f e r a t i o n rate.