The change in size of peripheral organs is one indicator used to describe effects of an intervention in experimental studies, or in observational studies.
It is common practice to express size in terms of organ-weight in relation to bodyweight. When effects on size as such are looked for, this can be misleading. The particular treatment may affect the weight of the organ, the total weight of body at the time for sacrifice and dissections, or affect the organ size and bodyweight. ‘Which’ bodyweight is used for reference will affect the results obtained.
To illustrate this point the results are presented of a study on the effects on organ-weight of an anabolic androgenic steroid: Nandrolone decanoate. Twenty-four (330–470 g) male Wistar rats (Taconic M&B, Ry, Denmark) were randomly divided in four treatment groups of six rats. The rats in each group received injections of either the vehicle (Arachidis oleum) or Nandrolone decanoate in one of three doses (1, 5 or 10 mg/kg). The rats received a daily injection subcutaneously (s.c.) for 19 days. The rats were sacrificed on the day following the last injections. The rats were weighed at the onset and end of the study.
The poster presents the weight of a selection of peripheral organs relative to individual pre-experimental and post-experimental weight, and relative to the dose given and growth over the treatment-period. The implications in each case are discussed in terms of effects on each target of the drug-treatment.