Anesthesia with alpha-chloralose in rats: it can be used for longitudinal fMRI studies

Introduction: Animal experimentation in neurosciences requires the use of anesthetics for animal welfare and cooperation. Two of the most widely used anesthetics for functional magnetic resonance imaging (fMRI) of animals are Isofluorane (Iso) and Alpha-Chloralose (AC). Iso is a volatile drug shown to be suitable to obtain fMRI images at low concentrations (1). AC is an injectable anesthetic with strong functional-metabolic coupling. On the other hand it can create physiological problems so it has been used as non recoverable. Nevertheless there are studies were AC was used on human patients and others were AC was used to anaesthetize and recover dogs and cats (2,3). To our knowledge, the non-recoverable concept has not been challenged properly for fMRI. Here we present a protocol for AC anesthetic preparation together with a fMRI study that shows that AC can be used as a recoverable anesthetic and has no effects on the fMRI results when animals are reused. Furthermore two parallel behavioral studies on recovered rats (Rotarot and Tail flick tests) show no effect on their brain and motor function.