Impact of an Implanted Intra-Abdominal Telemetry Transmitter on Fecal Excretion of Corticosterone and IgA in Adult Male F344 and BN Rats (Rattus norvegicus)
Telemetry is a widely used method for obtaining physiologic data from rats, but it is uncertain how distressing it is for the animals to live with an implanted transmitter for long periods. The present study aimed to assess this impact by analyzing 2 stress-sensitive biomarkers excreted in feces. Male Brown Norway (BN; n = 12) and Fisher 344 (F344; n = 12) rats were housed for 8 wk in IVCs and then for 8 wk in open top cages, in groups of 3, with one rat in each group carrying a transmitter. At 2-wk intervals, the rats were housed singly for 6 h (0600 to 1200), and voided fecal pellets were collected and frozen. Fecal glucocorticoids and fecal IgA from each rat were quantified and data subsequently analyzed using a repeated-measures mixed-model ANOVA. Both rat strain and transmitter carriage were found to significantly influence fecal corticosterone excretion. Overall, F344 rats excreted higher amounts of feces as compared with BN rats. In F344 rats with a transmitter the corticosterone values were 21% and in BN rats 47% higher than in controls, on average. Neither the rat strain nor an implanted transmitter seemed to have an impact on the amounts of fecal IgA excreted, but excretion increased significantly with age. In conclusion, in both rat strains, there was an increase in corticosterone excretion attributable to transmitter carriage, indicative of mild to moderate stress.
Fecal corticosterone excretion in 12 F344 and 12 BN male rats 2 to 32 wk after implantation of an abdominal telemetry transmitter. Results are expressed as means ± SEM. Both F344 and BN rats instrumented with a transmitter showed higher values for fecal corticosterone (P = 0.033) than did control rats. F344 rats excreted higher amounts as compared with BN rats (P = 0.015). Samples (n = 168, 55 samples from 8 transmitter rats and 113 samples from 16 rats without transmitter) were collected in 2-wk intervals.
Means of fecal corticosterone values from 12 F344 and 12BN rats plotted against rats’ age for both rat strains with and without transmitter. Samples (n = 168, 55 samples from 8 transmitter rats and 113 samples from 16 rats without transmitter) were collected in 2-wk intervals.
IgA excretion in 12 F344 and 12 BN male rats 14 to 32 wk after implantation of an abdominal telemetry transmitter. There were no statistically significant differences between the rat strains, but excretion increased over time (P = 0.010). Samples (n = 125, 43 samples from 8 transmitter rats and 82 samples from 16 rats without transmitter) were collected in 2-wk intervals.
Weight gain of F344 and BN male rats 2 to 32 wk after implantation of an abdominal telemetry transmitter. Results are expressed as means ± SD. There was a significant (P < 0.001) transmitter carriage × strain interaction. Both F344 and BN rats gained more weight with an implanted transmitter compared to those rats without a transmitter during the 16-wk study period, but in F344 rats the difference was larger. Animal weights (n = 192, 64 from 8 rats carrying transmitter and 128 from 16 rats without transmitter) were recorded in 2-wk intervals.
Contributor Notes