Neuronal transmitter sensitivity after social isolation in rats.

After 3 and 12 months of isolation rearing of rats, sensitivity of single neurons to microiontophoretically applied transmitters as well as neuronal spontaneous activity are analysed in striatum, cortex, hippocampus, locus coeruleus and nucleus raphis medialis. It is demonstrated that regulation of transmitter sensitivity, as well as spontaneous activity, depend on isolation duration, therefore showing time dynamics. Sensitivity changes of single neurons to distinct transmitters are not uniform and simultaneous in all areas but are structure specific. After 3 months of isolation an enhanced dopamine sensitivity is observed only in the striatum, whereas in the cortex the dopamine sensitivity is increased after 12 months isolation. A diminished response of single neuron activity to serotonin is demonstrable after 3 months of isolation in striatum and nucleus raphis. The observed changes are discussed in connection with biochemically and pharmacologically demonstrated changes in isolation. The complex patterns of neurobiological changes characterizing the isolation syndrome are emphasized.