RESUMO
We have proposed that passive responses observed following maternal separation in guinea pig pups represent "stress-induced sickness behaviors" mediated by proinflammatory processes. In this study, the anti-inflammatory peptide, alpha-melanocyte stimulating hormone (alpha-MSH) administered intracerebroventricularly, but not intraperitoneally, reduced the passive responses of crouching, eye-closing, and extensive piloerection relative to levels following administration of vehicle. These findings support our hypothesis and are as would be expected if pro-inflammatory processes act centrally to promote the passive behaviors of separated guinea pig pups.
Assuntos
Hormônios/administração & dosagem , Privação Materna , Papel do Doente , Estresse Psicológico/tratamento farmacológico , alfa-MSH/administração & dosagem , Fatores Etários , Animais , Animais Recém-Nascidos , Comportamento Animal/efeitos dos fármacos , Vias de Administração de Medicamentos , Feminino , Cobaias , Masculino , Piloereção/efeitos dos fármacos , Desempenho Psicomotor/efeitos dos fármacos , Estresse Psicológico/fisiopatologia , Vocalização Animal/efeitos dos fármacosRESUMO
When guinea pig pups are isolated in a novel environment, they show an initial active phase of behavioral responsiveness characterized by vocalizations and locomotor activity. One earlier study found that after about an hour, pups began to exhibit a second, passive stage of responsiveness marked by a crouched stance, eye-closing, and extensive piloerection. The present experiments tested the hypothesis that the responses during the second, passive stage result from the isolation experience activating pathways underlying the acute phase response, i.e., that behaviors of the second stage represent "stress-induced sickness behaviors". We found the following: (1) the passive stage did not emerge if pups remained with the mother during exposure to a novel cage; (2) injection of lipopolysaccharide, which induces an acute phase response, also led pups to exhibit crouching, eye-closing, and piloerection; and, (3) isolation in the novel cage produced a rise in rectal temperature, but did not affect peripheral or central levels of interleukin-1beta (IL-1beta)-immunoreactivity. Overall, these results are consistent with the notion that stress-induced sickness behaviors can account for some of the behaviors of isolated guinea pig pups, though if this is the case, cytokines other than IL-1beta appear to be involved.
