Journal of Neuroscience, Vol 7, 2035-2040, Copyright © 1987 by Society for Neuroscience
Effect of neurotensin on neurons in the periaqueductal gray: an in vitro study
MM Behbehani, MT Shipley and JH McLean
The effect of neurotensin (NT) on periaqueductal gray (PAG) neurons was
measured with extra- and intracellular recording methods in an in vitro
preparation. Neurons excited by NT were heterogeneously distributed, being
preferentially located in a region of PAG rich in NT-like fiber
immunoreactivity. The majority of the responsive neurons were located in
regions surrounding the aqueduct and the medial part of PAG. In 90% of the
neurons, application of NT produced excitation that lasted for more than 2
min, while in the remaining cells, the excitatory effect lasted for less
than 1 min. An inhibitory action of NT was rarely observed. Intracellular
recordings showed that NT produced a depolarization leading to an increase
in the spontaneous activity and multiple spiking with only a slight
decrease in membrane resistance. The excitatory effect of NT was observed
in neurons that were maintained in a solution containing cobalt. These
results support the hypothesis that NT action on PAG neurons is due to the
depolarization of the membrane and that this effect is mediated through a
postsynaptic mechanism.