Structural Bases Of The Noxious Stimulation Information Trnsmitting And Modulating And Distributions Of Amino Acid Receptors In Trigeminal Subnucleus Caudalis

The trigeminal subnucleus caudalis plays an important role in processing and relaying nociceptive information from face and oral cavity to thalamus and other brain regions. Stimulation of the nucleus raphe mag-nus can inhibit the neuronal responses to facial noxious stimulation in the trigeminal subnucleus caudalis (Vc). Both classical neurotransmitters andamino acid transmitters participate in controls of nociceptive information. However, morphological details of the connections between primary trigeminal afferent fibers and distributions of amino acid neurotransmitters and their receptors have not been delineated yet. In the present study, a series of experiments have been performed to reveal details of these connections at electeon microscopic level and the distributions of amino acids and their receptors at light microscopic level.I. Synaptic Connections between Substance P Receptor Positive and Thalamic Projection Neurons and Trigeminal Primary and Nucleus Raphe Magnus Descending Projection Terminals in the Trigeminal Subnucleus CaudalisLight microscopic observations show that the distributions of HRP transganglionically labeled trigeminal primary afferent terminals and PHA-L anterogradely labeled terminals originated from nucleus raphe magnus (RMg) overlap with each other in the superficial layers of the trigeminal subnucleus caudalis (Vc). Similarly , the distributions of substance P receptor positive neurons, thalamic projection neurons, trigeminal primary afferent fibers and RMg descending projection fibers aslo...