Distribution and projection of the medullary cardiovascular control neurons containing glutamate, glutamic acid decarboxylase, tyrosine hydroxylase and phenylethanolamine N-methyltransferase in rats.
This study was aimed at showing the distribution and projection of the medullary cardiovascular control neurons that contain a standard neurotransmitter or a related enzyme in the rat. A small amount of HRP was injected into either the depressor area of the caudal ventrolateral medulla (D-CVLM) or the pressor area of the rostral ventrolateral medulla (P-RVLM). Using an immunohistochemical method, we identified HRP-labelled neurons which were stained with antiserum to glutamate (Glu), glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH) or phenylethanolamine N-methyltransferase (PNMT). Our findings are summarized as follows. (1) The Glu-containing neurons in the nucleus tractus solitararii (NTS) project to the D-CVLM (n = 279, 100% assumed as a standard value) and P-RVLM (n = 225, 81% against the standard), indicating divergent excitatory projection. (2) The GAD-containing neurons in the NTS (n = 74, 27% against the standard) project to the P-RVLM, indicating the convergent inhibitory projection. (3) The projections of the TH-containing neurons from the NTS (n = 19, 7% against the standard) and CVLM (n = 4, 1% against the standard) to the P-RVLM are weaker than those of the GAD-containing neurons, suggesting that the catecholaminergic neurons play a minor role in inhibition of the sympathetic activity of the P-RVLM neurons. These results suggest that the glutamatergic NTS neurons excite both the P-RVLM and D-CVLM neurons, and the gamma-aminobutyric acid (GABA)ergic NTS and CVLM neurons inhibit the sympathetic activity of the P-RVLM neurons.
Suzuki
T
T
Department of Physiology 1st Division, Gunma University School of Medicine, Maebashi-shi, Japan.
Takayama
K
K
Miura
M
M
D000818:Animals; D001370:Axonal Transport; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000294:innervation*; D004558:Electric Stimulation; D005968:Glutamate Decarboxylase / Q000032:analysis*; D018698:Glutamic Acid / Q000032:analysis*; D005998:Glycine / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000502:physiology*; D008839:Microelectrodes; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D010625:Phenylethanolamine N-Methyltransferase / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D018698:Glutamic Acid; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D014446:Tyrosine 3-Monooxygenase; D010625:Phenylethanolamine N-Methyltransferase; D005968:Glutamate Decarboxylase; D005998:Glycine