Chronic, constant-rate, gastric drug infusion in nontethered rhesus macaques (Macaca mulatta).

As part of a study of antipsychotic drug treatment in monkeys, we developed a technique to provide chronic, constant-rate, gastric drug infusion in nontethered rhesus macaques. This method allowed us to mimic the osmotic release oral delivery system currently used in humans for continuous enteral drug delivery. Rhesus macaques (n = 5) underwent gastric catheter placement by laparotomy. After the catheters were secured to the stomach, the remaining catheter length was exited through the lateral abdomen, tunneled subcutaneously along the back, and connected to a 2-mL osmotic pump enclosed in a subcutaneous pocket. Osmotic pumps were changed every 2 to 4 wk for 1 y and remained patent for the duration of the study. Four complications (including cutting of the catheter, incisional dehiscence at the pump site, and loss of 1 catheter into the abdominal cavity requiring catheter replacement) occurred among the 80 pump changes performed during the year-long study. At necropsy, histopathologic examination of the catheter implant sites revealed mild changes consistent with a foreign-body reaction. Our results indicate that the gastric catheter and osmotic pump system was well tolerated in rhesus macaques for as long as 12 mo after placement and suggest that this system will be an attractive option for use in studies that require chronic, constant-rate, gastric drug infusion in nontethered monkeys.

Evaluation and comparative analysis of a technique for laparoscopic ovariectomy in rhesus macaques (Macaca mulatta).

Surgical ovariectomy is commonly performed to support studies involving the rhesus macaque (Macaca mulatta). Traditionally, these procedures have been performed via laparotomy. We developed a laparoscopic approach to reduce surgical pain, decrease convalescence times, and reduce the total number of animals necessary to obtain valuable scientific data in studies requiring repeated intra-abdominal access in conjunction with ovariectomy. We used our new technique to perform laparoscopic ovariectomy on 8 adult female rhesus macaques; 2 additional animals underwent ovariectomy via laparotomy; data for these prospective groups were compared with retrospective data from conventionally ovariectomized macaques. The surgical time (ST; mean +/- standard error) for the laparoscopic procedures was 68 +/- 3 min, with a return-to-group time (RTG) of 8 +/- 1 d. In comparison, ST for the retrospective group was 54 +/- 3 min, with a mean RTG of 33 +/- 5 d (range, 15 to 60 d). ST differed significantly between groups. ST for the laparoscopic procedure was longer (mean difference, 14 min; 95% confidence interval, 6 to 21 min), but laparotomized animals consistently had higher RTG (6 d for the prospective group [n = 2] and 25 d for the retrospective group [n = 9]). All study animals had estradiol levels of less than 5.6 pg/ml at 6 mo after surgery. We therefore conclude that laparoscopic ovariectomy of rhesus macaques is a safe and effective technique that may reduce postoperative recovery times.