Altered neurobiological responses to acute immobilization in social-isolated mice

Social isolation results in dynamic changes of neurobiological functions. The altered internal state of the CNS is reflected in changes in spontaneous behavior, changed responses to transmission-related substances and changed responsiveness to an additional impairment of normal relations between the organism and its environment. We analysed the influence of an acute 2-hour immobilization on such isolation-dependent changes. Whereas the susceptibility to pentetrazole-induced seizures increased continuously with lengthening of isolation and was not affected by the additional impairment, the responsiveness to transmission-related substances changed dynamically depending upon isolation-induced alterations. An immobilization-induced increase in responsiveness to LSD and propranolol was demonstrable in grouped controls and after short-term isolation. The apomorphine stimulation during prolonged isolation experienced a down- and an upregulation which were repeated in a stronger manner by immobilization responses especially after long-term isolation. It is suggested that the dynamics of isolation-induced changes coincided with changed acute adaptive functions.