Study of receptors, second messengers and DNA binding proteins on noxio usstimulation

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This study aimed at a demonstration for regulation of trigeminal sensory system by amino acids with using some histochemical technics, in situ hybridization histochemistry (ISH), immunohistochemistry and combination method of immunohistochemistry and retrograde tracer technic. We examined the expression of gamma-aminobutyric acid (GABA)_A receptor gamma1 and gamma2 subunit mRNAs in the rat trigeminal ganglion (TG) by ISH.Most TG cells expressed both gamma1 and gamma2 mRNAs simultaneously. Furthermore, expression of the gamma1 subunit in the primary sensory afferents was confirmed at the protein level by immunohistochemistry using antiserum against the gamma1 subunit. These findings indicate that primary sensory afferents receive GABAergic input, probably axo-axonically via GABA_A receptors expressing gamma1 and gamma2 subunits. We demonstrated that a few neurons projecting to the thalamus in the TNC (trigeminal nucleus caudalis) were labeled by antiserum that recognizes GluR1 and GluR2/3 subunits of the AMPA type receptor. However, expression of the gamma1 and gamma2 subunits of the GABA_A receptors indicated that several neurons projecting to the thalamus in the TNC receive GABAergic inputs via a GABA_A receptor which at contains least gamma1 and/or gamma2 subunits.