A morphological analysis of neurons in the lateral parabrachial nucleus: an intracellular horseradish peroxidase study in the rat

Abstract

Neurons in the lateral parabrachial nucleus (LPB) of the rat were analyzed by the intracellular horseradish peroxidase method. Sixteen LPB neurons were successfully labeled with HRP injected intracellularly. HRP-labeled LPB neurons were divided into type I (7 neurons) and type II (9 neurons) LPB neurons. Type I LPB neurons, which were activated antidromically by stimulation of the ipsilateral posteromedial ventral nucleus of the thalamus, had long dendrites and a long axon. Type II LPB neurons, which were not activated antidromically by the stimulation of the thalamus, had short dendrites and a short axon. It was concluded that type I LPB neurons were projection neurons, while type II LPB neurons were local circuit neurons.