Biomedical subjects

A P Nicholas

Publications and source records attributed to A P Nicholas.

22 records · Page 2Linked to original sources

PubMed1989

Evidence for substance P, serotonin and oxytocin input to medullary catecholamine neurons with diencephalic projections.

Using the retrograde transport of horseradish peroxidase (HRP) in combination with two-color immunoperoxidase staining, boutons stained with antisera to substance P (SP), serotonin (5HT) and oxytocin (OX) have been observed in contiguity with neurons in the rostral and caudal medulla that showed immunoreactivity for phenylethanolamine N-methyl transferase (PNMT) and tyrosine hydroxylase (TH), respectively, and which were backfilled with HRP injected into the diencephalon. The juxtaposition of these immunostained structures indicates that SP, 5HT and OX released from fibers in the medulla may affect the activity of adrenergic and noradrenergic medullary neurons that project to the diencephalon. Moreover, the presence of 5HT- and OX-immunoreactive processes in contiguity with medullary CA cells that send fibers to the diencephalon indicates that the raphe nuclei and the paraventricular nucleus of the hypothalamus can directly influence ascending pathways that are known to innervate the hypothalamus and appear to effect changes in vasopressin release.

Animals↗

PubMed1988

Immunocytochemical evidence for substance P and serotonin input to medullary bulbospinal adrenergic neurons.

Using two-color immunoperoxidase staining combined with the retrograde transport of horseradish peroxidase injected into the rostral thoracic spinal cord, substance P-immunoreactive (SPI) and serotonin-immunoreactive (5HTI) varicosities have been observed in contiguity with medullary bulbospinal phenylethanolamine N-methyl transferase-immunoreactive (PNMTI) neurons of the C1, C2, and C3 cell groups. Since PNMTI terminals in the spinal cord are concentrated among sympathetic preganglionic neurons (SPGN) in the intermediolateral cell column, the close anatomical associations shown in the present study indicate that substance P- and serotonin-containing pathways in the medulla likely affect activity of SPGN via adrenergic bulbospinal neurons.

Adrenergic Fibers↗

PubMed1987

Oxytocin-immunoreactive projections onto medullary adrenaline neurons.

With the use of two-color immunoperoxidase staining, oxytocin-like immunoreactive (OLI) processes have been observed along the surface of phenylethanolamine N-methyl transferase-like immunoreactive (PNMTLI) cells in the ventrolateral and dorsomedial medulla of the rat. OLI boutons were also observed on PNMTLI cells retrogradely labeled with HRP injected into the rostral thoracic spinal cord. The close spatial relationships between OLI processes and PNMTLI cells argues for a functional connection which could provide for direct hypothalamic control of medullary adrenaline cells involved in cardiovascular regulation.

Adrenergic Fibers↗

PubMedDate not supplied

Glutamate-like immunoreactivity in medulla oblongata catecholamine/substance P neurons.

Immunofluorescence histochemistry was performed on sections of the rat medulla oblongata with a well characterized antibody to the amino acid glutamate (GLU) combined with antisera to catecholamine synthesizing enzymes and substance P. GLU-like immunoreactive (LIR) neurons were seen in many areas of the medulla, and were particularly intensely stained in the rostral ventrolateral medulla. In this area, nearly all adrenaline neurons were GLU-LIR. This immunoreactivity was also seen in catecholamine neurons of the C2, C3, A1 and A2 cell groups. Many adrenaline neurons, especially of the C1 group, contained substance P-LI in addition to GLU-like immunoreactivity (LI).

Animals↗