Simultaneous assessment of central nervous and respiratory systems using jacketed telemetry in socially-housed rats: Application of the "3Rs" principles in core battery safety pharmacology studies.

Central nervous (CNS) and respiratory systems are routinely investigated in safety pharmacology core battery studies. For small molecules, the assessment of both vital organ systems is frequently done in rats in two distinct studies. With the advent of a miniaturized technology of jacketed external telemetry for rats (DECRO system), the simultaneous assessment of modified Irwin's or functional observational battery (FOB) test and respiratory (Resp) studies has become possible within a single study. Therefore, the objectives of this study were to perform the FOB and the Resp studies simultaneously in pair-housed rats fitted with jacketed telemetry, and to assess the feasibility and the outcome of this combination in control, baclofen, caffeine, and clonidine treated groups, i.e., with three agents having both respiratory and CNS effects. Our results provided evidence that performing both Resp and FOB assessment simultaneously in the same rat was feasible and the outcome was successful. The expected CNS and respiratory effects of the 3 reference compounds were accurately captured in each assay confirming the results' relevance. In addition, heart rate and activity level were recorded as additional parameters making this design as an enhanced approach for nonclinical safety assessment in rats. This work provides clear evidence that the "3Rs" principles can be effectively applied in core battery safety pharmacology studies while remaining in compliance with worldwide regulatory guidelines. Both reduction in animal use and refinements in procedures are demonstrated with this model.