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P Popper

Publications and source records attributed to P Popper.

49 records · Page 3Linked to original sources
PubMed1990

In situ hybridization for the study of gene expression in neuro-otologic research.

In situ hybridization histochemistry technology was developed for future application to neuro-otologic research. This method allowed the detection of cellular mRNA in tissue sections from the temporal bone or brainstem after cRNA/mRNA hybridization. To produce specific cRNA, single-stranded 35S-labeled cRNA (complimentary to target mRNA) is transcribed from commercially available plasmid vectors. These vectors contain promotor sequences for specific synthesis of RNA, and polylinker regions that will accept cloned DNA inserts for virtually any target nucleic acid sequence of interest. The protocol used in this research was optimized for studies that included concomitant immunohistochemical evaluation. The combination of in situ hybridization and immunohistochemistry provides the only method to correlate molecular information (gene expression) with biochemical or molecular markers, such as peptides or proteins (mRNA translation products) on individual cells in the temporal bone or brainstem. Using these techniques, we examined the distribution of the neuropeptide calcitonin gene-related peptide in rat temporal bone and brainstem sections using calcitonin gene-related peptide (CGRP) antisera and CGRP cRNA probes. We used in situ hybridization histochemistry with a cRNA probe complementary to the 3'-end noncoding sequence of the alpha CGRP mRNA and immunohistochemistry with a polyclonal antibody to the (TYR)CGRP23-37 to study the distribution of CGRP mRNA and CGRP-like immunoreactivity in the central and peripheral facial nerve. Numerous motoneuron cell bodies in the facial nucleus and accessory seventh nucleus and cell bodies in the gustatory geniculate ganglion were found to contain CGRP mRNA and the CGRP peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Academies and Institutes↗
PubMed1989

Localization of calcitonin gene-related peptide and its receptors in a striated muscle.

The distribution of calcitonin gene-related peptide (CGRP) and its binding sites in the bulbocavernosus, a striated muscle, are reported. We used immunohistochemistry and [125I]CGRP autoradiography. The pattern of [125I]CGRP binding was restricted to a discrete band that coincides with the distribution of end-plates in this muscle as determined by CGRP immunohistochemistry and acetylcholinesterase staining. CGRP has been shown to increase the level of acetylcholine receptor (AChR) alpha-subunit mRNA. The role of CGRP as the endogenous factor by which motoneurons regulate the expression of junctional AChR is discussed.

Animals↗
PubMed1989

The effect of castration on calcitonin gene-related peptide in spinal motor neurons.

The spinal nucleus of the bulbocavernosus (SNB) is a sexually dimorphic nucleus of about 200 androgen-accumulating motor neurons in lumbar segments 5 and 6 of the rat spinal cord. In the present work we have used immunohistochemistry to investigate the change in calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) in these motor neurons induced by long-term castration. CGRP-LI was found in the cell bodies of the SNB motor neurons and in thin varicose fibers coursing through the nucleus. In the intact animals 48.4 +/- 3.9% (n = 8) of the SNB neurons were CGRP-LI positive while in the castrates this ratio increased to 80.0 +/- 1.7% (n = 9, p less than 0.001). Animals castrated for 4 weeks and then implanted with testosterone-containing Silastic capsules for an additional 4 weeks had the same percentage of CGRP-LI-containing SNB motor neurons as intact animals. These results demonstrate that a reduction in circulating testosterone levels increases the number of SNB motor neurons that express CGRP-LI implying that androgen stimulation inhibits the expression of CGRP-LI in SNB motor neurons.

Animals↗
PubMedDate not supplied

The localization of sensory nerve fibers and receptor binding sites for sensory neuropeptides in canine mesenteric lymph nodes.

Previous work has established that the central nervous system can modulate the immune response. Direct routes through which this regulation may occur are the sympathetic and sensory innervation of lymphoid organs. We investigated the innervation of canine mesenteric lymph nodes using immunohistochemistry and the expression of binding sites for sensory neuropeptides using quantitative receptor autoradiography. The sympathetic innervation of lymph nodes was examined by immunohistochemical methods using an antiserum directed against tyrosine hydroxylase (TOH), the rate limiting enzyme in catecholamine synthesis. TOH-containing fibers were associated with 90% of the blood vessels (arteries, veins, arterioles and venules) in the hilus, medullary and internodular regions of lymph nodes and in trabeculae with no obvious relationship to blood vessels. The sensory innervation of lymph nodes was investigated using antisera directed against the putative sensory neurotransmitters calcitonin gene-related peptide (CGRP) and substance P (SP). CGRP- and SP-containing fibers were detected in the hilus, the medullary region, and the internodular region of lymph nodes usually in association with arterioles and venules. About 50% of the arterioles and venules exhibited a CGRP innervation and a smaller fraction (5-10%) were innervated by SP-containing fibers. Few if any TOH, CGRP, and SP nerve fibers were detected in the germinal centers of lymph nodes. Using quantitative receptor autoradiography we studied the distribution of receptor binding sites for the sensory neuropeptides CGRP, SP, substance K (SK), vasoactive intestinal peptide (VIP), somatostatin (SOM), and bombesin. Specific CGRP binding sites were expressed throughout lymph nodes by trabeculae, arterioles, venules and 25% of the germinal centers. SP receptor binding sites were localized to arterioles and venules in the T cell regions and 25-30% of the germinal centers. VIP binding sites were localized to the internodular and T cell regions, to medullary cords, and to 10-20% of germinal centers. SK, SOM, and bombesin binding sites were not detected in the lymph nodes, although receptor binding sites for these peptides were detected with high specific/nonspecific binding ratios in other canine peripheral tissues. Taken together with previous results these findings suggest that the sympathetic and sensory innervation of mesenteric lymph nodes appears to be involved with the regulation of their blood and lymph flow. The neuropeptide receptor binding sites in lymph node germinal centers may be expressed by lymphocytes upon activation by antigens.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Distribution of choline acetyltransferase mRNA in the efferent vestibular neurons of the chinchilla.

The distribution of choline acetyltransferase messenger RNA (mRNA) among efferent vestibular neurons in the chinchilla was investigated. mRNA coding for choline acetyltransferase, the enzyme that synthesizes acetylcholine, was used as a marker for the cholinergic system. In order to retrogradely label the efferent vestibular neurons, Fluoro-gold was injected through the oval window into the inner ear of anesthetized young male chinchillas (6 to 12 months old). The animals were anesthetized and perfused through the heart 2 days post injection with 4% paraformaldehyde in phosphate buffer. Retrogradely labeled efferent vestibular neurons were mapped in brainstem sections prior to processing for in situ hybridization histochemistry using radiolabeled ribonucleic acid probes complementary to the 3' end of the choline acetyltransferase mRNA. At the levels of the ascending facial nerve and the genu of the facial nerve, we found that approximately 90% of the Fluoro-gold labeled cells in group E1 contained choline acetyltransferase mRNA. All of the group E2 cells that were labeled with Fluoro-gold were found to be cholinergic (contain choline acetyltransferase mRNA). Finally, 60% of the Fluoro-gold-labeled cells in the caudal pontine reticular nucleus contained choline acetyltransferase mRNA.

Animals↗