On the use of α-chloralose for repeated BOLD fMRI measurements in rats.

Most animal experiments in neurosciences require anesthesia of the experimental animal. For fMRI experiments most neuroscientist would prefer (I) a recoverable anesthesia that would (II) allow strong BOLD responses which are (III) reproducibly obtained for the same animal in repetitive experiments. Strong BOLD responses are particularly needed if weak physiological stimuli like whisker deflection are used. A-chloralose, in contrast to isoflurane, fulfils the need for strong activation but has been traditionally considered as a terminal drug due to its negative physiological side effects. Here it is demonstrated, that new commercial α-chloralose in a careful application scheme allows for repeated fMRI studies on the same animal with similar responses after whisker stimulation. Only minor effects on the normal behavior were observed between drugs. These include a longer time to return to baseline values of food ingestion and slower tail reaction for the α-chloralose experiments.