Effects of Hypothermia on the In Vivo Measurement of Rapid Axonal Transport in the Rat: A Cautionary Note

: Rapid axonal transport of glycoproteins was examined in the retinofugal projections of hypothermic and normothermic adult male Long-Evans hooded rats previously receiving intraocular injections of [3H]fucose. The amount of retinal fucosylation appeared normal in the hypothermic animals 3.5 h after isotope injection, but glycoprotein transport was reduced relative to normothermic controls. This reduction was especially pronounced in the most distal structure of the retinofugal tract (superior colliculus). We conclude that rapid axonal transport decreases with reductions in mammalian body temperature. This finding emphasizes the importance of controlling body temperature in in vivo studies of mammalian axonal transport.