INFLUENCE OF FOOD MANIPULATION ON PLASMA CORTICOSTERONE, INNATE IMMUNITY, AND BLOOD CHEMISTRY IN THE BROWN AFRICAN HOUSE SNAKE (LAMPROPHIS FULIGINOSUS)

Abstract

The ability to tolerate the stress of extended periods of food restriction is an evolutionarily important trait that has significant effects on survivorship in the wild. There are different physiological mechanisms by which certain species survive these periods: elevation of the stress hormone corticosterone, reduction of immune function, and reduction in reproductive activity are well documented responses to food restriction. These responses to food shortage have been documented in species ranging from mammals to amphibians, but to my knowledge, have not been performed within a sex-based context in colubrid snakes. Thus the objectives of this project are to document the effects of food manipulation and sex on plasma corticosterone, innate immunity and blood chemistry in the African brown house snake, Lamprophis fuliginosus. Sex differences would seem especially likely in reptile species that are strongly sexually dimorphic, such as the African brown house snake. With their larger body mass, females would be expected to have the capacity for much larger energy reserves than males and thus experience less dramatic changes in physiology in response to food restriction. This project consisted of a ten week food restriction period in which twenty-four snakes (16 female, 8 male) were fed just 5% of their body mass every two weeks and a five week recuperation period during which all snakes were fed ad lib. During the 15week project, four blood samples were collected from each snake to measure corticosterone, bacterial killing capacity (with E. coli), hemolytic capacity (with sheep RBC), leukocytes, testosterone, estradiol, triglyceride, and uric acid concentrations. I predicted that corticosterone would increase during the 10-week period of food restriction and that as corticosterone increases, immune function would decrease with varying degrees between the sexes.