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Exposure to short days, but not short‐term melatonin, enhances humoral immunity of male Syrian hamsters ( Mesocricetus auratus )
Author(s) -
Drazen Deborah L.,
Jasnow Aaron M.,
Nelson Randy J.,
Demas Gregory E.
Publication year - 2002
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1034/j.1600-079x.2002.02915.x
Subject(s) - mesocricetus , melatonin , biology , immune system , keyhole limpet hemocyanin , hamster , rodent , photoperiodism , phodopus , medicine , endocrinology , testosterone (patch) , immunity , humoral immunity , physiology , immunology , ecology
Many non‐tropical rodent species rely on photoperiod as the primary cue to co‐ordinate seasonally appropriate changes in physiology and behavior. Among these seasonal changes, several rodent species (e.g. deer mice, prairie voles, Siberian hamsters) adjust immune function in response to changes in ambient day lengths. The goals of the present study were to examine the effects of photoperiod on immune function of Syrian hamsters ( Mesocricetus auratus ), and to determine the role of melatonin in mediating photoperiodic changes in immunity. In Experiment 1, male Syrian hamsters were housed in long (LD 14:10) or short days (LD 10:14) for 10 wk. In Experiment 2, hamsters were housed in long days and half of the animals were given 10 consecutive days of i.p. melatonin injections (15 μg) in the early evening, while the remaining animals received injections of the vehicle alone. After the respective experimental manipulations, animals were injected with the antigen, keyhole limpet hemocyanin (KLH), blood samples were obtained and anti‐KLH IgG antibody production was assessed. In Experiment 1, short‐day hamsters underwent gonadal regression and reduced serum testosterone as well as displayed increased humoral immune function compared with long‐day animals. In Experiment 2, short‐term melatonin treatment did not affect gonadal mass, testosterone or humoral immune function. These results confirm previous findings of photoperiodic changes in immunity in rodents and suggest that changes in humoral immunity are not due to short‐term changes in melatonin.