The paraventricular nucleus of the hypothalamus sends efferents to the spinal cord of the rat that closely appose sympathetic preganglionic neurones projecting to the stellate ganglion

• Published in: Experimental brain research 1998-05, Vol.120 (2), p.164-172
• Main Authors: RANSON, R. N, MOTAWEI, K, PYNER, S, COOTE, J. H
• Format: Article
• Language: English
• Subjects: Anatomy; Animals; Autonomic Fibers, Preganglionic - physiology; Axons - physiology; Biological and medical sciences; Biotin - analogs & derivatives; Brain research; Central nervous system; Cholera Toxin; Dextrans; Efferent Pathways - physiology; Fluorescent Dyes; Fundamental and applied biological sciences. Psychology; Hypothalamus; Injections; Iontophoresis; Male; Neural circuitry; Neurons - physiology; Paraventricular Hypothalamic Nucleus - physiology; Physiological aspects; Properties; Rats; Rats, Wistar; Spinal Cord - physiology; Stellate Ganglion - physiology; Sympathetic Nervous System - cytology; Sympathetic Nervous System - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s002210050390

Using a combination of anterograde and retrograde neuronal tract-tracing techniques, the descending projections from the paraventricular nucleus of the hypothalamus (PVN) to the brain/spinal cord and in particular those axonal projections that appear to be contiguous with sympathetic preganglionic neurones (SPN) projecting to the stellate ganglion have been studied. Descending PVN pathways were located by the anterograde transport of biotinylated dextran amine (BDA), whilst SPN were retrogradely labelled with cholera B toxin subunit conjugated to horseradish peroxidase (CB-HRP). BDA-labelled PVN axons terminated in both hypothalamic and extrahypothalamic (including the midbrain, medulla and spinal cord) brain nuclei, with dense terminal labelling observed particularly in the arcuate hypothalamic nucleus and adjacent median eminence, in the solitary tract, vagal nuclei and in the intermediolateral region of the spinal cord (IML). Varicose descending PVN fibres in the IML were often observed to closely appose both the cell soma and dendrites of retrogradely labelled SPN (projecting to the stellate ganglion) in the spinal cord. In addition, it was shown that PVN descending axons crossing to the contralateral side of the spinal cord were closely associated with retrogradely labelled SPN projecting to the superior cervical ganglion. Such findings suggest that descending pathways from the PVN may exhibit a direct influence on cardiac sympathetic outflow and may also influence the behaviour of the contralateral population of SPN projecting to the superior cervical ganglion.