This study has investigated the possibility that acetylcholinesterase could play a non-classical role as an adhesion factor or growth factor in the development of dopaminergic neurons in organotypic slice culture of postnatal day 1 rats. When the culture medium was supplemented with acetylcholinesterase (3 U/ml), outgrowth of tyrosine hydroxylase-immunoreactive neurites was significantly enhanced. Addition of a specific inhibitor of acetylcholinesterase, BW284c51, caused a decrease in the number of tyrosine hydroxylase neurons and a reduction in the cell body size and extent of neurite outgrowth of remaining neurons. However, echothiophate which also inhibits AChE activity, did not produce these effects. Therefore acetylcholinesterase could act as a growth enhancing factor for dopaminergic neurons, and disruption of an as yet unidentified site on the acetylcholinesterase molecule by BW284c51 could decrease the survival and outgrowth of these neurons.
This article explores contemporary tactics of dispossession in the still-frontier towns of Alice Springs and Darwin in the Northern Territory (NT) of Australia, using the politics of walking to bring what was considered a past act of colonial incursion into conditions of the present. Much of the historical material on Australian race relations deploys accounts of violent massacres, authorized dispossessions, and cruel imprisonments to depict the frontier politics of liberal settler occupation. Certainly the settlement histories of Darwin and Alice Springs lend themselves to such renditions. Within the desert and tropical savannah hinterlands, settlers poisoned and destroyed food sources, cleared vegetation, subdivided land, brutally monopolized precious water supplies, and dragooned a lumpenproletariat of semitrained Aboriginal workers into pastoral and mission-led enterprises. Crude attempts at assimilation followed earlier attempts to "breed out the black." The spatiality of colonization mimicked the demarcations of European imperialism elsewhere: an apartheid system of curfews and restricted movements prevailed until well after World War II. Only then were the legal rights of Aboriginal people to fair and equal treatment as citizens of Australia increasingly reflected in changing regulatory and resourcesharing agreements. With the constitutional referendum of 1967, when Australians voted to confer greater legal status to Aboriginal people (essentially conferring the
Acetylcholinesterase (AChE) is secreted from various brain regions such as the substantia nigra, where levels of this molecule are disproportionately higher than those of choline acetyltransferase. It is thus possible that AChE may have alternative, non-cholinergic functions, one of which could be in development. Indeed, several recent studies have already demonstrated a neurotrophic action of AChE independent of hydrolysis of acetylcholine. In the developing nervous system the dominant forms of AChE differ from the tetramers (G4) that prevail in maturity, in that they are lower molecular weight monomers (G1) and dimers (G2). Therefore, the aims of this study were to explore the neurotrophic role of AChE by comparing the effects of mouse recombinant G1 and G4 AChE on the survival and development of mid-brain tyrosine hydroxylase immunoreactive neurons. Butyrylcholinesterase (BuChE), which also hydrolyses acetylcholine, and basic fibroblast growth factor (bFGF), an established trophic factor for midbrain neurons, were also tested. bFGF had no significant stimulatory effect: moreover, BuChE was also inefficacious, suggesting that the action of AChE was independent of its catalytic site. In contrast, mouse recombinant G1 and G4 AChE both increased the survival as well as the outgrowth of the cultured neurons. However, G1 AChE was more potent than G4 AChE suggesting that developmental forms of AChE exist. The implications of this finding for physiological and pathological functioning of the nervous system are discussed.
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