title: Regulation of immunocompetence by different androgen metabolites in a blenny with alternative reproductive tactics.
abstract: In Parablennius parvicornis, small reproductive males with relatively low expression of secondary sexual characters (M- morphotype) parasite on the parental investment of the larger nest-holder males which have fully developed secondary sexual characters (M+ morphotype). In comparison with M+ males, M- males have relatively low levels of androgens while having high blood cell percentages of lymphocytes and antigen responsiveness. Here we test the hypothesis that androgens are a causal factor for these differences in immunocompetence between morphotypes. After drawing an initial blood sample, males received a silastic implant containing either oil only (C), or oil with testosterone (T) or 11-ketotestosterone (KT). Males were re-caught 2 weeks later for drawing of the final blood sample. KT but not T induced the development of secondary sexual characters in M- males. M- males treated with KT showed lower swimming activity than the males treated with T or C implants, suggesting that KT also mediates behavioral changes in M- males. As expected, blood cell percentages of lymphocytes, but not of granulocytes, were higher in M- males than in M+ males. Overall, lymphocyte percentages increased in the C group which might have been a response to the surgery/treatment. In concordance with the hypothesis, lymphocyte percentages were suppressed in males treated with T in comparison with controls. However, no significant change was found in KT-treated males. This suggests that androgens modulate central, morphological and immunological traits by partly independent androgen mechanisms in P. parvicornis.
authors.affiliation: Instituto Superior de Psicologia Aplicada, Unidade em Eco-Etologia, 1149-041 Lisbon, Portugal. aros@ispa.pt
authors.forename: Albert Frank Huascar
authors.initials: AF
authors.lastname: Ros
authors.forename: Catarina
authors.initials: C
authors.lastname: Ferreira
authors.forename: Ricardo Serrão
authors.initials: RS
authors.lastname: Santos
authors.forename: Rui Filipe
authors.initials: RF
authors.lastname: Oliveira
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D007121:Immunocompetence / Q000187:drug effects*; D008124:Locomotion / Q000187:drug effects; D018655:Lymphocyte Count; D008297:Male; D010473:Perciformes / Q000033:anatomy & histology / Q000097:blood / Q000276:immunology*; D012727:Sex Characteristics; D013739:Testosterone / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology*
chemical_list: D013739:Testosterone; C003600:11-ketotestosterone