MENGO VIRUS-INDUCED CORTICOSTERONE LEVELS IN GROUP-HOUSED AND INDIVIDUALLY HOUSED MICE

Infection of male C57BL/6 mice with Mengo virus evoked a significant i ncrease (up to 2 fold) in serum corticosterone from 24 to 120 hours af ter inoculation. This increase was significantly larger in individuall y-housed mice that, as a group, also died of infection at a significan tly higher percentage compared to,coup-housed subjects. Subjects that succumbed to infection exhibited a higher defecation score in open fie ld tests conducted two to three weeks prior to virus inoculation. In a separate experiment it was shown that animals with high defecation sc ores in the open field had significantly higher corticosterone levels after open field exposure than subjects with low defecation scores. It is concluded that increased corticosterone responsiveness, whether ch aracterized by open field testing or induced by social isolation, is d etrimental for coping with Mengo virus infection. These results sugges t that a fine-tuned optimum exists for the glucocorticoid feedback mec hanism under virus infection.