A membrane glycoprotein associated with the limbic system mediates the formation of the septo-hippocampal pathway in vitro

The ability of a neuronal surface glycoprotein to mediate the formation of neuronal connections was tested in an explant culture system. A monoclonal antibody against the limbic system-associated membrane protein (LAMP) was used in co-cultures containing cholinergic neurons of the septum and their hippocampal target neurons. Antibody treatment had no effect on general axon outgrowth, but significantly diminished the ability of septal cholinergic axons to invade and collateralize in the hippocampus. The results suggest that factors regulating general axon outgrowth may be distinct from those regulating the patterns of outgrowth that define the formation of neural circuits.

Hyperthermia protects against light damage in the rat retina

An increase in the synthesis of heat shock proteins that is induced in cells in vitro by hyperthermia or other types of metabolic stress correlates with enhanced cell survival upon further stress. To determine if a similar increase in stress tolerance could be elicited in vivo, rats were made hyperthermic, and then their retinas were tested for sensitivity to light damage. This treatment resulted in a marked decrease in photoreceptor degeneration after exposure to bright light as compared to normothermic animals. Concomitant with such protection was an increase in retinal synthesis of three heat shock proteins. Thus, a physiological rise in body temperature enhances the stress tolerance of nerve tissue, perhaps by increasing heat shock protein production.