Flow cytometry and immunochemical methods are applied to embryonic rat spinal and supraspinal regions to study the development, differentiation and cellular distribution of transmitters and their corresponding receptor- coupled alterations in membrane excitability. At present this multidisciplinary investigation is focused on elucidation of a developmental calendar outlining the expression of specific transmitters and their functional receptors with a primary focus on the development of the GABA phenotype and a secondary focus on the glutamate phenotype. Principal observations this year include: 1) immunological detection of GAD-related proteins during embryonic development of the rat spinal cord with low molecular weight proteins apparent in many neurons before the advent of AB:,the product of GAD enzyme activity; 2) progressive appearance of GABA+ fibers, then GABA+ neurons during embryogenesis along rostrocaudal and ventrodorsal axes in the spinal cord coincident with the appearance of high molecular weight GAD proteins; 3) postnatal emergence of a second set of GAD-related proteins with a subcellular distribution and colchicine sensitivity characteristic of vesicular transport in neurons also immunoreactive for embryonic GAD proteins; 4) biochemical dejection of GABA transiently derived from ornithine and increasingly synthesized by GAD in embryonic rat cortex; 5) sizable secretion of GABA in vitro under resting conditions from embryonic cortical neurons; 6) early embryonic appearance of functional voltage-gated Na+ channels and depolarizing GABA-A progesterone metabolite receptors in rat cortex, cerebellum and thalamus; 7) in situ hybridization evidence of GABA-A receptor subunit beta receptor message preceding a subunit message throughout the embryonic rat CNS; 8) emergence of depolarizing GABA-A receptors along a rostrocaudal gradient throughout the early embryonic chick CNS; 9) critical requirement of GABA-A receptors for chick spinal cord neuron adherence in vitro and process formation; 10) arrival of spinothalamic tract projections in the thalamus about the time of birth in the rat.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Intramural Research (Z01)
Project #
1Z01NS002330-13
Application #
3881719
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
13
Fiscal Year
1990
Total Cost
Indirect Cost
City
State
Country
United States
Zip Code