ABSTRACT
Alterations in synaptic efficacy induced by antigen challenge to isolated superior cervical ganglia (SCG) were monitored by measuring the magnitude of the postganglionic compound action potential (CAP) elicited by electrical stimulation of the cervical sympathetic nerve trunk. Antigen-induced changes in the CAP were measured in SCG removed from actively and from passively sensitized guinea-pigs. Additionally, some SCG were sensitized in vitro by incubating naive ganglia 24 h in serum obtained from actively sensitized animals. Histamine released from SCG upon specific antigenic challenge was measured to assess the effectiveness of the two forms of sensitization. Challenging SCG isolated from passively or actively sensitized animals with the sensitizing antigen, ovalbumin (OVA), produced a sustained potentiation of the CAP lasting longer than 30 min (antigen-induced long-term potentiation, A-LTP) and a net increase in histamine release. Neither the magnitude nor duration of A-LTP induced by passive sensitization differed significantly (p < 0.05) from results after active sensitization. The existence of A-LTP in SCG following passive sensitization indicates that the afferent limb of the immune system is not required for the development of this phenomenon and that the immune cells and the mediators responsible for A-LTP are resident to sympathetic ganglia.
Subject(s)
Immunization, Passive , Neuronal Plasticity/immunology , Superior Cervical Ganglion/immunology , Vaccination , Afferent Pathways/immunology , Animals , Antigens/pharmacology , Electrophysiology , Guinea Pigs , Histamine Release/immunology , Hypersensitivity, Immediate/immunology , Long-Term Potentiation/immunology , Male , Mast Cells/physiology , Ovalbumin/immunology , Superior Cervical Ganglion/cytology , Superior Cervical Ganglion/ultrastructure , Synapses/immunology , Synaptic Transmission/immunologyABSTRACT
Groups of rats housed since weaning under two different kinds of housing conditions (wire and wooden cages) were compared at adulthood in the open field test, the step-through passive avoidance test, and for aggressiveness induced by REM-sleep deprivation and apomorphine administration. In the open field test wire-caged rats showed less rearing and grooming than wood-caged rats. This difference was accentuated by a single previous electrical shock (i.e., wire-caged rats exhibited less ambulation, rearing and grooming and more defecation than wood-caged rats, after shock) and was not altered by prior habituation to handling. In the passive avoidance test there were no significant differences between wire- and wood-caged rats. Wire-caged rats were more aggressive than wood-caged rats after REM-sleep deprivation and the administration of apomorphine. These results show that the control of previous housing conditions is an important variable to be considered in behavioral studies.
