Immunological regulation of synaptic transmission in isolated guinea pig autonomic ganglia

We have attempted to identify a role for mast cells in autonomic ganglia by examining the effects of antigen challenge on mast cell-associated mediator release and synaptic transmission through the superior cervical ganglion isolated from ovalbumin-sensitized guinea pigs. Ovalbumin induced the release of 7.9 ng of histamine, 40 pg of immunoreactive sulfidopeptide-leukotriene, and 140 pg of immunoreactive-PgD₂ per ganglion. Ovalbumin produced long-lasting potentiation (51 ± 4%, mean ± SEM, n = 66) of synaptic transmission, the protracted nature of which could not be mimicked by exogenous histamine (10^-5 M). Selective histamine H1 antagonists inhibited the antigen-induced potentiation, but did not reverse it when added any time after antigen exposure. These results indicate that immunologic activation of mast cells can directly potentiate neurotransmission in sympathetic ganglia. Histamine appears to be a mediator involved in the induction of antigen-induced potentiation of synaptic transmission, but alone cannot account for the long term nature of this phenomenon.