Testing the immunocompetence handicap hypothesis: Testosterone manipulation does not affect wound healing in male salamanders.
In vertebrates, a bidirectional relationship exists between the immune system and the hypothalamic-pituitary-gonadal axis. In addition, sexual dimorphism in immunity has been documented in many vertebrates as well as some invertebrates, and males are generally less immunocompetent than their female counterparts. A possible explanation for this is described by the immunocompetence handicap hypothesis (ICHH), which proposes that elevated testosterone (T) levels direct resources towards the promotion of secondary sexual characteristics at a cost to immune function. To further test the ICHH, we examined the effects of T on cutaneous wound healing, an integrative measure of immunity, using male Allegheny Mountain dusky salamanders; a species that has sexually dimorphic courtship glands and testosterone-dependent mating behavior. We did this via two methods: surgical manipulation and transdermal delivery of T. In both experiments, elevated plasma T did not delay wound healing. Interestingly, intact animals healed more slowly than animals that had undergone prior invasive surgery, suggesting that the prior surgery had an immune-priming effect that enhanced healing of a second wound.
Department of Biological Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, USA. Electronic address: jethomas@clarion.edu.
Jessica R
JR
Thomas
Department of Biological Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, USA.
Sarah K
SK
Woodley
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003345:Corticosterone / Q000097:blood; D007121:Immunocompetence; D008297:Male; D008954:Models, Biological; D009043:Motor Activity / Q000187:drug effects; D013739:Testosterone / Q000097:blood / Q000494:pharmacology*; D014562:Caudata / Q000097:blood / Q000502:physiology*; D014945:Wound Healing / Q000187:drug effects*
D013739:Testosterone; D003345:Corticosterone
Hormones; Immunity; Plethodontid; Reproduction; Trade-offs