901–87 Serum Cholesterol and Lipoprotein Concentrations in Black Bears

Abstract

Elevated serum cholesterol (CHOL) concentration and low HDL concentration are linked to the development of atherosclerotic heart disease (AHD). High CHOL levels have been reported in both denning and non-denning bears, yet coronary artery atherosclerosis has not been observed. Lipoprotein measurements in black bears have not been reported. This study investigates the concentrations of CHOL and lipoproteins in denning and non-denning black bears. Serum CHOL concentrations were measured in 1052 serum samples drawn from wild black bears in both the denning and non-denning states. Non-denning bears were immobilized with ketamine (5 mg/kg) and xylazine (2 mg/kg) whereas denning bears were immobilized with ketamine (12 mg/kg) or tiletamine and zolezapam (4.5 mg/kg). Serum total lipids (TUP), CHOL and lipoproteins were measured in ten denning bears (4 males, 3 females and 3 lactating females with cubs). CHOL and lipoproteins also were measured in a non-denning female. Denning bears were fasting whereas non-denning bears were trapped with high fat content foods and were non-fasting. Non-denning bears had significantly lower CHOL levels than denning bears. CHOL levels in denning bears were higher in early winter (Nov/Dec) than late winter (Feb/Mar). Males had higher CHOL levels than females during winter, but not during summer. Yearlings had lower CHOL levels than adults in winter. In the subpopulation of ten denning bears, TLIP were 1247 ± 454 mg/dl (range 639–2167); triglycerides (TRIG) were 351 ± 180 mg/dl (range 111–680); CHOL were 376 ± 162 mg/dl (range 175–695); HDL were 111 ± 35 mg/dl (range 82–185); LDL were 129 ±66 mg/dl (range 47–228); and VLDL were 53 ± 22 mg/dl (range 22–87). HDL, LDL and VLDL levels were not ascertained in three bears because the precipitation technique was not possible and triglycerides were too high. The CHOL/HDL ratio was 2.8 ± 1.1 (range 1.7–4.8). Values at the lower range for TLIP, TRIG, CHOL, LDL and VLDL in this subgroup were found in two of the lactating females, who also had high HDL concentrations. Values for the non-denning female were TRIG 318, CHOL 298, HDL 210, LDL 24, VLDL 64 and CHOL/HDL 1.4. This bear recently had consumed 10 kgs of bacon. This study confirms previous reports that CHOL levels are high in black bears, especially during denning. Further, it demonstrates that, although CHOL, LDL and VLDL concentrations were in the range associated with development of human AHD, the HDL levels were much higher than observed in most human studies. In fact, the CHOL/HDL ratio was low to low-normal in all bears, including the bear which had consumed a high fat meal. These data imply that a high HDL concentration, along with a low CHOL/HDL ratio, confers protection against development of AHD in black bears despite high serum lipid concentrations. Further investigation could yield information of therapeutic benefit for man.