Dynorphin immunocytochemistry in the rat central nervous system

The distribution of dynorphin in the central nervous system was investigated in rats pretreated with relatively high doses (300-400 micrograms) of colchicine administered intracerebroventricularly. To circumvent the problems of antibody cross-reactivity, antisera were generated against different portions as well as the full dynorphin molecule (i.e., residues 1-13, 7-17, or 1-17). For comparison, antisera to [Leu]enkephalin (residues 1-5) were also utilized. Dynorphin was found to be widely distributed throughout the neuraxis. Immunoreactive neuronal perikarya exist in hypothalamic magnocellular nuclei, periaqueductal gray, scattered reticular formation sites, and other brain stem nuclei, as well as in spinal cord. Additionally, dynorphin-positive fibers or terminals occur in the cerebral cortex, olfactory bulb, nucleus accumbens, caudate-putamen, globus pallidus, hypothalamus, substantia nigra, periaqueductal gray, many brain stem sites, and the spinal cord. In many areas studied, dynorphin and enkephalin appeared to form parallel but probably separate anatomical systems. The results suggest that dynorphin occurs in neuronal systems that are immunocytochemically distinct from those containing other opioid peptides.

Localization of immunoreactive dynorphin in neurons cultured from spinal cord and dorsal root ganglia

Antisera specific for dynorphin were used to study the cellular distribution of opioid peptides in spinal cord and dorsal root ganglion neurons in dissociated cell culture. Radioimmunoassay of 4-wk-old cultures yielded levels of dynorphin immunoreactivity similar to those in adult rodent spinal cord. Immunohistochemistry showed staining confined to the perinuclear region of neuronal cell bodies. In contrast, enkephalin immunoreactivity was found in extensive neurite fields as well as in neuronal perikarya. Opioid peptide immunoreactivity was observed in approximately equal to 5% of the spinal cord neurons either with dynorphin or enkephalin antiserum. No substantial increase in the number of reactive cells was observed when the two sera were applied simultaneously. These results suggest that the perinuclear region of opioid spinal cord neurons in culture contains peptide with an amino acid sequence similar to that of the midportion of dynorphin, whereas the neurites appear to contain smaller peptides related to NH2-terminal fragments of dynorphin. By using simple morphological criteria, spinal sensory neurons can be identified in these cell cultures and in cultures prepared from dorsal root ganglia without spinal cord. Approximately 1-2% of these ganglion cells showed intense immunostaining with an affinity-purified dynorphin antiserum. An additional few percent of the sensory neurons showed less intense opioid immunoreactivity. This result extends the observations of opioid peptides one step further along the pathway that processes sensory information.

Reduction in opiate receptor reserve in morphine tolerant guinea pig ilea

Spare opiate receptors in the guinea pig ileum have been detected by the use of the opiate receptor alkylating agent beta-chlornaltrexamine (CNA). Treatment of the guinea pig ileum longitudinal muscle in vitro with low concentrations (less than 10nM) of CNA resulted in an irreversible parallel shift to the right of the normorphine log concentration response curve. With increasing concentration of the reagent, the agonist EC50 becomes progressively greater. Finally a point is reached at which the maximal agonist effect decreases, so that parallelism is no longer seen. The maximal parallel shift provides a measure from which one can estimate the spare receptor fraction that is present in untreated tissue. In ilea from normal guinea pigs, roughly 80-90% of the opiate receptors for normorphine were found to be spare. Even after the largest parallel shifts that could be achieved, the naloxone Ke value for antagonism was unchanged, indicating that normorphine acts through spare mu receptors. Ilea from guinea pigs made tolerant by chronic morphine pellet implantation were found to be more sensitive to the effects of CNA treatment; there was a reduction in the number of spare receptors for normorphine. It is suggested that the opiate spare receptor fraction is physiologically modulated to control neuronal sensitivity to opioid effect.

Opioid peptide identity and localization in hippocampus

The hippocampus contains three times as much dynorphin-17 immunoreactivity (ir) as enkephalin-ir. Hippocampal mossy fibers exhibit weak enkephalin and strong dynorphin immunostaining. Intrahippocampal colchicine injections, which selectively destroy dentate granule cells, reduce enkephalin-ir and dynorphin-ir in mossy fibers. Intraventricular kainic acid, which causes degeneration of CA3-4 pyramidal cells, results in increased enkephalin immunostaining in mossy fibers. The enkephalin-ir cells and fibers of the entorhinal cortex which innervate the hippocampus and dentate gyrus do not contain dynorphin-ir.

Symptom complaints of patients maintained on methadone, LAAM (methadyl acetate), and naltrexone at different times in their addiction careers

In this study, side effect complaints were compared between methadone patients on a stable dose with no heroin use for at least 3 months and matched non-drug-using controls; between methadone patients when using and not using heroin; and between patients in treatment (stable dosage, no heroin use for at least one month) and at follow-up, when not using any opiates and no longer in treatment. This last comparison was done for methadone, LAAM (l-alpha-acetylmethadol, methadyl acetate), and naltrexone patients. Methadone patients had more complaints than did non-drug-using controls; patients in methadone treatment felt worse when using heroin than when not using heroin; methadone, LAAM, and naltrexone patients felt worse while in treatment than when they left treatment and stopped using all opiates; the level of complaints for patients abstinent from opiates at follow-up was not different from that reported by non-drug-using controls. The difficulty of ascribing the symptom complaints to the drugs, in the absence of placebo-treated control groups, is discussed.

Isolation and amino acid sequence analysis of a 4,000-dalton dynorphin from porcine pituitary

A 4,000-dalton dynorphin was isolated from porcine pituitary. It has 32 amino acids (Mr = 3,986), with the previously described heptadecapeptide (now called dynorphin A) at its amino terminus and a related tridecapeptide, dynorphin B, at its carboxyl terminus. The two peptides are separated by the "processing signal" Lys-Arg.

A dynorphin-like opioid in the central nervous system of an amphibian

We have provided evidence for the existence of a biologically active opioid in toad (Bufo marinus) brain that is immunoreactive with antiserum raised against dynorphin (1-13). Compared with porcine dynorphin, this opioid is similar in apparent molecular weight on the basis of gel permeation chromatography and is more hydrophobic on the basis of high-performance liquid chromatography. After purification, its opioid biological activity was demonstrated on the guinea pig ileum myenteric plexus-longitudinal muscle preparation. It was found to be less potent, and to have a similar sensitivity to antagonism by naloxone, in comparison with porcine dynorphin. Because it is immunoreactive with antiserum specific for porcine dynorphin, it probably has considerable sequence homology. Generally, the tissue distribution of immunoreactive dynorphin in the toad is similar to that in the rat, with highest concentrations in the neurointermediate lobe of the pituitary. However, the anterior lobe of the toad pituitary contains considerably lower concentrations than are found in the rat anterior lobe. There appear to be three size classes of immunoreactive dynorphin in toad neural tissue, each with apparent molecular weight below 12,000, similar to the size classes of immunoreactive dynorphin found in pig and rat. However, in toad spinal cord (and possibly in brain) there is immunoreactive dynorphin of greater apparent molecular weight, which has not been reported in mammalian tissue. The contribution of each molecular size to the total immunoreactivity varies from tissue to tissue and is different from that observed in the rat.

Dynorphin and vasopressin: common localization in magnocellular neurons

The opioid peptide dynorphin is widely distributed in neuronal tissue of rats. By immunocytochemical methods, it was shown previously that dynorphin-like immunoreactivity is present in the posterior pituitary and the cells of the hypothalamic neurosecretory magnocellular nuclei which also are responsible for the synthesis of oxytocin, vasopressin, and their neurophysins. By using an affinity-purified antiserum to the non-enkephalin part of the dynorphin molecule it has now been demonstrated that dynorphin and vasopressin occur in the same hypothalamic cells of rats, whereas dynorphin and oxytocin occur in separate cells. Homozygous Brattleboro rats (deficient in vasopressin) have magnocellular neurons that contain dynorphin separate from oxytocin. Thus dynorphin and vasopressin, although they occur in the same cells, appear to be under separate genetic control and presumably arise from different precursors.

B-scan transducer peak frequency measurement by diffraction grating spectroscopy

Making use of technology developed for optics, transmission diffraction grating spectroscopy is proposed as a method of measuring ultrasound transducer frequencies. Diffraction grating theory is presented and extended to the case of a new test object proposed to measure a B-scan transducer's peak frequency. A prototype test object was built and its feasibility tested. The experimental results indicate that the test object performed well and has high measurement precision. The question of measurement accuracy was not resolved by the feasibility test. This complex point is discussed in detail. Recent improvements of the test object and the author's ongoing studies of diffraction grating characteristics are presented.

Dynorphin is a specific endogenous ligand of the kappa opioid receptor

In the guinea pig ileum myenteric plexus--longitudinal muscle preparation, dynorphin-(1--13) and the prototypical kappa agonist ethylketocyclazocine had equally poor sensitivity to naloxone antagonism and showed selective cross protection in receptor inactivation experiments with the alkylating antagonist beta-chlornaltrexamine. In binding assays with membranes from guinea pig brain, ethylketocyclazocine and dynorphin-(1--13) amide were more potent in displacing tritium-labeled ethylketocyclazocine than in displacing typical mu and delta opioid receptor ligands. In the two preparations studied, the dynorphin receptor appears to be the same as the kappa opioid receptor.

Visualization of B-scan transducer transverse cross-sectional beam patterns

A technique has been developed to "fool" a B-scanner into imaging the transverse cross-sectional beam pattern of its transducer. This technique can be easily used by clinical personnel to test in-house transducers under their normal conditions of use. The effects of various equipment parameters on the effective beam pattern and the image spatial resolution are demonstrated. It is shown that the technique may be used easily and accurately to measure transducer connector/acoustic axis misalignment.

Ultrasound pulse-echo reflection from test object cylindrical reflectors

This paper is a first attempt at answering the question of which strong reflectors are most useful in ultrasound test objects. A planar reflector placed in the transducer far field has demonstrated potential as a standard reference reflector for pulse-echo ultrasound studies. Measurements of echo temporal voltage waveform and frequency spectrum from various metallic and plastic cylindrical reflectors were performed and compared to the results obtained with the planar reflector. Relatively undistorted echos were obtained from metallic cylinders when the condition lambda > 3D was obeyed, as well as large attenuating plastic cylinders when the condition lambda << D was obeyed. Consideration of these results along with mechanical and corrosion data leads to the identification of thin stainless steel type 302, nickel and molybdenum wires, as well as thick Oilon Pv 80 rods as potentially good reflectors for ultrasound test objects. The observed mechanical resonant frequencies of metallic cylinders has been shown to be potentially useful as a temperature-independent frequency standard in suitably designed test objects. The potential use of thin Teflon cylinders for transducer axial resolution measurement has been demonstrated.

Immunoreactive dynorphin in mammalian spinal cord and dorsal root ganglia

The distribution of immunoreactive dynorphin (ir-dynorphin) has been determined in dorsal and ventral aspects of spinal cord and in dorsal root ganglia of rabbit and rat. Concentrations are highest in dorsal root, with intermediate levels in ventral cord and low levels in dorsal root ganglia of both species. Levels of ir-dynorphin are relatively uniform over examined segments (vertebrae C2-S3) of rabbit spinal cord and dorsal root ganglia. Gel permeation chromatography of extracts from rabbit dorsal and ventral spinal cord and dorsal root ganglia revealed at least three immunoreactive components of differing molecular size in all three structures. Multiple unilateral or bilateral dorsal rhizotomy (vertebrae C5-T1) in rat did not affect levels of ir-dynorphin in spinal cord. As reported [Goldstein, A. & Ghazarossian, V. E. (1980) Proc. Natl. Acad. Sci. USA 77, 6207-6210], midthoracic spinal transection was without effect. Within the spinal cord, the neuropeptide appears, most probably, to be contained in short-axoned neurons. We surmise that this potent opioid peptide may participate in the processing of sensory information in spinal cord.

Endothelial cell presentation of antigen to human T cells

Activation of human T cells requires presentation of antigen by Ia (HLA-DR in man) bearing cells of the mononuclear phagocytic series (macrophages, MO, and more recently Langerhans cells, dendritic cells, and vascular endothelial cells. Since T cells must cross endothelial barriers to enter extravascular tissues during immune reactions, we investigated the role of endothelial cells in antigen presentation. Endothelial cells were cultured from human umbilical veins and identified by classic morphology and specific markers (factor VIII related antigen, and so on). Antigen-pulsed endothelial cells were used to present antigen to MO-depleted human T cells; activation was assessed by 3H-thymidine uptake. The HLA-DR compatible endothelial cells were as effective as MO in reconstituting MO-depleted T-cell responses. The endothelial cell reconstituted responses were antigen specific, HLA-DR restricted, and blocked by monoclonal antibodies to HLA-DR framework structures. Moreover, the T-cell responses were clonal with respect to HLA-DR. A monoclonal antibody completely eliminated MO reconstitution of the MO-depleted response without diminution of endothelial cell reconstitution of the same response. Fibroblasts and smooth muscle cells cultured from the same umbilical veins could not reconstitute the MO-depleted T-cell response. These data indicate that endothelial cells play an important and distinctive role in lymphocyte triggering.

Porcine pituitary dynorphin: complete amino acid sequence of the biologically active heptadecapeptide

The full primary structure of the very potent opioid peptide dynorphin, from porcine pituitary, has been determined. It is (H)Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Ile-Arg-Pro-Lys-Leu-Lys-Trp-Asp-Asn-Gln(OH). The synthetic peptide with this sequence behaves identically to natural dynorphin in a number of ways, and it has the same potency in the guinea pig ileum myenteric plexus--longitudinal muscle bioassay. The potency is accounted for by the first 13 residues.

Specific receptor for the opioid peptide dynorphin: structure--activity relationships

The structural features responsible for the high potency and opiate receptor specificity of the opioid peptide dynorphin in the guinea pig ileum myenteric plexus were examined. Successive removal of COOH-terminal amino acids from dynorphin-(1--13) demonstrated important contributions of lysine-13, lysine-11, and arginine-7 to the potency. Removal of the NH2-terminal tyrosine abolished the biologic activity. Several other structural modifications were shown to affect potency: substitution of D-alanine for glycine-2 reduced the potencies of dynorphin-(1--13) amide, -(1--11), and -(1--10); and methyl esterification of the COOH terminus enhanced the potencies of dynorphin-(1--12), -(1--10), -(1--9), -(1--8), and -(1--7). Within the dynorphin sequence, lysine-11 and arginine-7 were found to be important for selectivity of interaction with the dynorphin receptor, which is distinguishable from the mu receptor in this tissue.

Slice-thickness artifacts in gray-scale ultrasound

We have become increasingly aware of the presence of a type of image artifact normally appearing in anechoic areas (eg, cyst, bladder, gallbladder) and giving the appearance of "sludge" or "debris." These artifactual echoes may be caused by the fact that the finite width of the transducer beam pattern produces a finite thickness of the patient scan plane. All echoes produced in this "thick" scan plane are misinterpreted as being due to structures in the normally assumed "thin" scan plane. We have tested and verified this hypothesis by simulating soft tissue interfaces with 400 grit silicon carbide sandpaper in a water tank. A set of clues are proposed to enable the rapid identification of these artifacts.