Biomedical subjects

D L Bellinger

Publications and source records attributed to D L Bellinger.

41 records · Page 3Linked to original sources

PubMed1984

Sympathetic innervation of lymph nodes in mice.

Noradrenergic innervation of popliteal and mesenteric lymph nodes in mice was examined with fluorescence histochemistry. Dense varicose plexuses entered the nodes with the vasculature in the hilar region and continued with the vasculature into the medullary region. Fine, delicate varicosities and small vascular plexuses continued into the cortical and paracortical regions surrounding the germinal centers; some varicosities ended among lymphocytes. A subcapsular plexus contributed fibers into the cortical and paracortical regions. Chemical measurements revealed the presence of norepinephrine in lymph nodes that was depletable with 6-hydroxydopamine. Depletion of norepinephrine from lymph nodes with this agent resulted in a diminished primary immune response in draining lymph nodes following subcutaneous injection of an antigen in two mouse strains, but had no effect in two other strains. These findings suggest that noradrenergic fibers innervate both the vasculature and parenchymal regions of lymph nodes, and may participate in the modulation of immune responses in these organs.

Adrenergic Fibers↗

PubMed1984

Catecholamine innervation of cervical dendrite bundles: possible phrenic nucleus innervation.

The catecholaminergic innervation of three recently described dendrite bundles (midline, central and lateral) in the cervical spinal cord of the adult Long-Evans hooded rat [41] was examined using Golgi impregnation, fluorescence histochemistry for catecholamines, and cholinesterase histochemistry. The midline and lateral bundles were similar in appearance to those described by the Scheibel and Scheibel [50,51], while the central bundle, present in the region of the phrenic nucleus, has not been described previously. Analysis of Golgi-Cox impregnated horizontal sections demonstrated the presence of fine varicose fibers within all three bundles. These profiles entered the bundles at right angles, either singly or within small transverse dendritic subunits, then turned in a rostral or caudal direction, and coursed adjacent to dendrites of motoneurons in the bundles. Catecholamine histofluorescence in horizontal sections revealed abundant varicosities within all three bundles, similar in size and appearance to the varicose fibers seen in Golgi-Cox impregnated sections. Catecholamine fibers entered the dendrite bundles at right angles then turned rostrally or caudally and coursed horizontally within the bundles. Varicose fluorescent profiles formed pericellular rings around the motoneurons and linear profiles adjacent to the dendrites, sometimes outlining the entire proximal portion of primary dendrites. Catecholamine fibers entered the dendrite bundles at right angles then turned rostrally or caudally to course adjacent to the dendrites within the bundles. Cholinesterase histochemistry in alternate sections revealed staining of motoneurons and their dendrites, and confirmed the location of the catecholamine varicosities within the motoneuron dendrite bundles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Substance P innervation of the rat thymus.

Immunohistochemistry for substance P (SP) in the rat thymus revealed fine varicose neural profiles in specific regions of the thymus. Thymic SP innervation was abundant within the capsule and interlobular septa. The majority of SP+ nerve fibers within the septa were free of vascular association, although some fibers were associated with the vasculature deep within the septa. SP+ nerve fibers entered the thymic cortex from the septa and distributed among cortical thymocytes and mast cells. Along the corticomedullary junction, SP+ nerve fibers were found in association with the vasculature. The medullary region of the thymus received only a sparse innervation of SP+ fibers. In addition, SP+ nerve fibers coursed adjacent to OX-8+ cells and mast cells in the extrathymic connective tissue surrounding the thymus. The present study provides evidence that SP is present in nerve fibers in the thymus, and may be available to interact with thymocytes, mast cells, and other cells in the thymus, and affect their development and function.

Animals↗

PubMedDate not supplied

Decreased sympathetic innervation of spleen in aged Fischer 344 rats.

Splenic noradrenergic innervation in young adult and aged Fischer 344 rats was examined using fluorescence histochemistry for catecholamines and high performance liquid chromatography with electrochemical detection (LCEC) for the quantitation of norepinephrine (NE). In young adult rats, abundant noradrenergic plexuses followed the vasculature and trabeculae into splenic white pulp. In aged rats, noradrenergic innervation was reduced in density and in overall intensity of fluorescence, and splenic NE levels were significantly lower. The relationship between diminished noradrenergic innervation and diminished immune responsiveness in aging mammals, while not clear on a causal level, is presented as a hypothesis for further testing.

Aging↗

PubMedDate not supplied

Age-associated alterations in sympathetic neural interactions with the immune system.

We have examined age-related alterations in sympathetic noradrenergic (NA) innervation in primary and secondary lymphoid organs from mouse and rat. As the thymus involuted with age, the density of NA innervation and norepinephrine (NE) concentration increased markedly. Total thymic NE was not altered significantly with age, suggesting that NA innervation is maintained as the thymus involutes. In the rat spleen, NA innervation and NE concentration were diminished with age. Enhanced antibody responses and in vitro proliferation to a T-dependent protein antigen were observed following selective destruction of NA nerve fibers with the neurotoxin 6-hydroxydopamine (6-OHDA), demonstrating that the diminished NA innervation in the aged spleen is capable of signaling the immune system. Plasticity of NA nerves in old rats was demonstrated following lesioning with 6-OHDA and in intact rats treated with L-deprenyl, a monoamine oxidase B inhibitor. These age-related alterations in NA innervation of lymphoid organs occur concurrently with age-associated changes in immune function. Understanding the functional relationship between these two physiological systems in aging will contribute to a greater understanding of sympathetic nervous system regulation of immune function.

Age Factors↗