Long-term sustained delivery of androgens by means of TCPL devices and the effect on high-density lipoprotein in castrated rams.

Several studies have established that conventional routes of androgens administration resulted in a decrease in high-density lipoprotein cholesterol (HDL-C), a major risk factor for coronary artery disease. The HDL-C response to the long-term sustained delivery of androgens by means of tricalcium phosphate-lysine implants (TCP-L) has not been investigated. Suffolk rams (40-57 kg) were used for this investigation. A total of 11 rams were castrated by elastrater rings at birth. At 7 months of age, these animals were randomly divided into three groups. Group 1 rams (n = 3) served as control group. Groups 2 (n = 4) and 3 rams (n = 4) were implanted subcutaneously into the axillary region with sterilized (ethylene oxide) TCP-L capsules, containing testosterone (T) and Dihydrotestosterone (DHT), respectively. Blood samples (5 ml) were collected from the experimental and control animals by jugular venipuncture weekly for 12 months. After blood samples were allowed to clot (12 hours), serum was separated by centrifugation and stored at -20 degrees C until analyzed. Circulating T and DHT levels were measured by solid-phase radioimmunoassay and HDL-C and protein by colorimetric method and lipoprotein fractions mobility by electrophoresis. The results demonstrated that after castration, the HDL-C concentrations increased significantly in all animals (P < .001). Sustained delivery of T (4-6 ng/ml) and DHT (1.5-2 ng/ml) produced a significant decrease in HDL-C (P < .001), in which was similar to HDL-C reductions seen when the animals were treated with DHT-TCPL (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)