Refinements for Intragastric Gavage in Rats
Intragastric (IG)-gavage is widely used in laboratory rats in pharmacological, toxicological and pharmacokinetic studies. This technique has been claimed to result in severe stress and a variety of complications. This study was designed to compare the stress response caused by IG-gavage with steel and teflon probes, to determine whether any habituation occurred to repeated gavaging and to find out whether the use of different administration volumes within the recommended range influenced the stress response. Telemetrically registered cardiovascular responses were used to assess the stress-producing effects. During laparoscopy, transmitters with a catheter extending into the abdominal aorta were implanted into the peritoneal cavity of male Wistar rats. IG-gavage induced a significant increase in diastolic and systolic blood pressure and heart rate, lasting for about 40 minutes. IG-gavage with a stainless steel probe induced greater changes in cardiovascular parameters. It can be concluded that teflon probes are preferable because they elicit less discomfort to the animals. Repeating the IG-gavage with a teflon probe daily evoked a decrease of all parameters on the fourth day as compared with the previous days, but this did not occur in the stainless steel group. The volume administered through IG-gavage had significant effects on diastolic blood pressure, systolic blood pressure and heart rate. Surprisingly, volumes of 2 and 4 ml / kg body weight resulted in a greater response in cardiovascular parameters than volumes of 6 and 8 ml/kg. It appears that there is a window of preferred administration volumes. A routine cage change induced an increase in diastolic blood pressure, systolic blood pressure and heart rate comparable to the changes observed after IGgavage. In conclusion, our data indicate that use of IG-gavage with a soft teflon probe and volumes 6 and 8 ml/kg are obvious refinements for the procedure.