Heart Disease has been cited as the foremost cause of captive adult male gorilla deaths. Given that captivity does not offer gorillas the same level of physical activity and diet as their wild counterparts, one hypothesis for captive gorilla heart disease etiology is that akin to metabolic syndrome-related heart disease in humans. To address this; hormonal data on leptin, insulin, glucose, cholesterol, oxidized low-density lipoprotein, prolactin, and ferritin serum concentrations were collected with concurrent echocardiograph data [ejection fraction (EF), interventricular septum thickness (IVS), left ventricle posterior wall thickness (LVPW), and left ventricle internal diameter at diastole (LVIDd)] to assess any association between these biomarkers and cardiac health when controlling for age. The Quantitative Insulin Sensitivity Check Index was used as a proxy measurement of insulin sensitivity. Diagnoses were provided for 30 individual male gorillas with 11 diagnosed as without heart disease and 19 diagnosed with heart disease.
Results demonstrate that any association between these hormones and echocardiograph parameters is strongly mediated by age. Unpredictably, results also indicate insulin sensitivity is negatively associated with EF. Insulin values probably underscore that relationship. This would suggest that EF may be preserved by the upregulation of glucose metabolism over beta-oxidation in cardiac cells. Although not significant, a negative associational trend between prolactin and LVIDd might also indicate another compensatory pathway against further cardiac dilation. If so, cardiac disease progression in this sample may be well underway despite diagnoses and age. Given the complexity of both, the relationships between these hormones and echocardiographic data, and among the hormones themselves, further analysis is needed to assess the relationships between captive gorilla hormonal profiles and cardiac health along age graded classes. Determinations of baseline insulin sensitivity also need further refinement to provide better context when exploring captive gorilla cardiac disease.