Voltage-dependent inhibition of Ca2+ channels in GH3 cells by cloned mu- and delta-opioid receptors

To study cloned opioid receptor binding and modulation of both adenylyl cyclase and ion channel activity, we stably expressed mu- and delta-opioid receptors in the rodent pituitary-derived GH3 cell line. GH3 cells express G proteins and voltage-activated Ca2+ channels (predominantly of the L-type). Activation of cloned rat mu-opioid receptors expressed in GH3 cells (termed GH3MOR cells) inhibits L-type Ca2+ channel activity. GH3MOR cells, further transfected with mouse delta receptor cDNA (termed GH3MORDOR cells), bound both [D-Ala2,N-MePhe4,Gly-ol5]enkephalin (DAMGO) and [D-Pen2,D-Pen5]enkephalin (DPDPE). These opioid ligands inhibited adenylyl cyclase activity (IC50 = 174 and 0.53 nM, respectively). This action of DAMGO and DPDPE was attenuated selectively by mu- and delta-opioid receptor-specific antagonists. Activation of both opioid receptors also led to inhibition of Ca2+ channel activity, measured with Ba2+ as the charge carrier using the whole-cell patch-clamp technique. Both DAMGO (1 microM) and DPDPE (1 microM) reversibly inhibited Ba2+ currents (by 17.0 +/- 1.4% and 20.7 +/- 1.3%, respectively) in GH3MORDOR cells. The inhibitory action of DPDPE was dose dependent (IC50 = 1.6 nM) and was attenuated by pretreatment with pertussis toxin (200 ng/ml) or by the inclusion of guanosine-5'-O-(2-thio)diphosphate (2 mM) in the recording electrode. Ba2+ current inhibitions by both DAMGO and DPDPE were completely reversed by depolarizing (to > 50 mV) prepulses in GH3MORDOR cells. In summary, cloned mu- and delta-opioid receptors expressed in GH3 cells voltage-dependently couple through Gi/G(o) proteins to L-type Ca2+ channels.

Mu opioid receptor-like sequences are present throughout vertebrate evolution

The sequence of the mu opioid receptor is highly conserved among human, rat, and mouse. In order to gain insights into the evolution of the mu opioid receptor, polymerase chain reaction (PCR) was used to screen genomic DNA from a number of different species using degenerate oligonucleotides which recognize a highly conserved region. DNA was assayed from representative species of both the protostome and deuterostome branches of the metazoan phylogenetic tree. Mu opioid receptor-like sequences were found in all vertebrate species that were analyzed. These species included bovine, chicken, bullfrog, striped bass, thresher shark, and Pacific hagfish. However, no mu opioid receptor-like sequences were detected from protostomes or from any invertebrates. The PCR results demonstrate that the region of the mu opioid receptor gene between the first intracellular loop and the third transmembrane domain (TM3) has been highly conserved during evolution and that mu opioid receptor-like sequences are present in the earliest stages of vertebrate evolution. Additional opioid receptor-like sequence was obtained from mRNA isolated from Pacific hagfish brain using rapid amplification of cDNA ends (RACE). The sequence of the Pacific hagfish was most homologous with the human mu opioid receptor (72% at the amino acid level between intracellular loop 1 and transmembrane domain 6) although over the same region high homology was also observed with the delta opioid receptor (69%), the kappa receptor (63%), and opioid receptor-like (ORL1) (59%). The hagfish sequence showed low conservation with the mammalian opioid receptors in the first and second extracellular loops but high conservation in the transmembrane and intracellular domains.

Morphine activates opioid receptors without causing their rapid internalization

We have examined the endocytic trafficking of epitope-tagged delta and mu opioid receptors expressed in human embryonic kidney (HEK) 293 cells. These receptors are activated by peptide agonists (enkephalins) as well as by the alkaloid agonist drugs etorphine and morphine. Enkephalins and etorphine cause opioid receptors to internalize rapidly (t1/2 approximately 6 min) by a mechanism similar to that utilized by a number of other classes of receptor, as indicated by localization of internalized opioid receptors in transferrin-containing endosomes and inhibition of opioid receptor internalization by hypertonic media. Remarkably, morphine does not stimulate the rapid internalization of either delta or mu opioid receptors, even at high concentrations that strongly inhibit adenylyl cyclase. These data indicate that agonist ligands, which have similar effects on receptor-mediated signaling, can have dramatically different effects on the intracellular trafficking of a G protein-coupled receptor.

Immunohistochemical localization of ORL-1 in the central nervous system of the rat

A novel member of the opioid receptor family (ORL-1) has been cloned from a variety of vertebrates. ORL-1 does not bind any of the classical opioids, although a high affinity endogenous agonist with close homology to dynorphin has recently been identified. We have generated a monoclonal antibody to the N-terminus of ORL-1 to map areas of receptor expression in rat central nervous system (CNS). Intense and specific immunolabeling was observed in multiple areas in the diencephalon, mesencephalon, pons/medulla, and spinal cord. In the telencephalon, intense labeling was observed in the neuropil throughout layers II-V in the neocortex, the anterior olfactory nuclear complex, the pyriform cortex, the CA1-CA4 fields and dentate gyrus of the hippocampus, and in many of the septal and basal forebrain areas. In contrast to other members of the opioid receptor family, light labeling for ORL-1 was observed in telencephalic areas such as caudate-putamen. In the cerebellum, ORL-1 immunoreactivity was only observed in the deep nuclei. Throughout the CNS the majority of labelling was localized to fiber processes and fine puncta, although labeled scattered perikarya were observed in a few brain areas such as the hilus dentate in the hippocampus and some nuclei in the brainstem and spinal cord. The present mapping study is consistent with the reported distribution of ORL-1 mRNA and provides the first immunohistochemical report on anatomical and cellular distribution of ORL-1 receptor in the rat CNS.

Opioid receptor types and subtypes: the delta receptor as a model

Since the discovery of opioid receptors over two decades ago, an increasing body of work has emerged supporting the concept of multiple opioid receptors. Molecular cloning has identified three opioid receptor types--mu, delta, and kappa--confirming pharmacological studies that previously postulated the existence of these three receptors. The cloned opioid receptors are highly homologous and belong to the family of seven-transmembrane, G protein-coupled receptors. With the development of novel opioid ligands, subtypes of the mu, delta, and kappa receptors have been proposed, although the molecular basis of these subtypes has not been elucidated. In this review, we present the pharmacological data supporting the concept of multiple delta opioid receptor subtypes and offer hypothetical mechanisms which might generate these "subtypes."

Test optics error removal

Wave-front or surface errors may be divided into rotationally symmetric and nonrotationally symmetric terms. It is shown that if either the test part or the reference surface in an interferometric test is rotated to N equally spaced positions about the optical axis and the resulting wave fronts are averaged, then errors in the rotated member with angular orders that are not integer multiples of the number of positions will be removed. Thus if the test piece is rotated to N equally spaced positions and the data rotated back to a common orientation in software, all nonrotationally symmetric errors of the interferometer except those of angular order kNθ are completely removed. It is also shown how this method may be applied in an absolute test, giving both rotationally symmetric and nonsymmetric components of the surface. A general proof is given that assumes only that the surface or wave-front information can be described by some arbitrary set of orthognal polynomials in a radial coordinate r and terms in sin θ and cos θ. A simulation, using Zernike polynomials, is also presented.

Irreversible binding of cis-(+)-3-methylfentanyl isothiocyanate to the delta opioid receptor and determination of its binding domain

Binding of cis-(+)-3-methylfentanyl isothiocyanate (SUPERFIT) to cloned opioid receptors stably expressed in Chinese hamster ovary cells was characterized. SUPERFIT inhibited [3H]diprenorphine binding with much higher affinity for the delta than the mu or kappa receptor. Pretreatment with SUPERFIT followed by extensive washing reduced delta binding with an IC50 value of 7.1 nM, yet it did not affect mu and kappa binding up to 0.1 microns. The reduction in delta binding by SUPERFIT pretreatment was due to a decrease in Bmax with no change in Kd. These results indicate that SUPERFIT is a highly selective delta irreversible ligand. We then determined the region in the delta receptor that confered binding selectivity for SUPERFIT by examining its binding to six mu/delta chimeric receptors. SUPERFIT bound to delta, mu/delta 1 (amino acids mu 1-94/delta 76-372), delta/mu 3 (delta 1-134/mu 154-398), and delta/mu 4 (delta 1-187/mu 207-398) receptors with high affinity but to mu, delta/mu 1 (delta 1-75/mu 95-398), mu/delta 3 (mu 1-153/delta 135-372), and mu/delta 4 (mu 1-206/delta 188-372) receptors with low affinity. Pretreatment with SUPERFIT potently inhibited [3H]diprenorphine binding to delta, mu/delta 1, delta/mu 3, and delta/mu 4 but affected binding to mu, delta/mu 1, mu/delta 3, and mu/delta 4 only at much higher concentrations. Thus, the segment from the beginning of the first intracellular loop to the middle of the third transmembrane helix of the delta receptor is important for selective binding of SUPERFIT.

Visualization of surface figure by the use of Zernike polynomials

Commercial software in modern interferometers used in optical testing frequently fit the wave-front or surface-figure error to Zernike polynomials; typically 37 coefficients are provided. We provide visual representations of these data in a form that may help optical fabricators decide how to improve their process or how to optimize system assembly.

Test of a slow off-axis parabola at its center of curvature

We describe the interferometric testing of a slow (ƒ/16 at the center of curvature) off-axis parabola, intended for use in an x-ray spectrometer, that uses a spherical wave front matched to the mean radius of the asphere. We find the figure error in the off-axis mirror by removing the theoretical difference between the off-axis segment and the spherical reference from the measured wave-front error. This center of curvature test is easy to perform because the spherical reference wave front has no axis and thus alignment is trivial. We confirm that the test results are the same as the double-pass null test for a parabola that uses a plane autocollimating mirror. We also determine that the off-axis section apparently warped as the result of being cut from the symmetric parent part.

Induction of opioid receptor-mediated macrophage chemotactic activity after neonatal brain injury

Macrophages have a prominent role in the injury response of the brain, yet the molecular mechanisms that control their invasion to the site of neuronal degeneration is unknown. After removal of the posterior cortex at birth, there is massive and specific targeting of nonresident macrophages to axotomized neurons in the lateral thalamus. The present study has identified an injury-induced, brain-derived chemotactic factor (BDCF) capable of eliciting chemotactic responses from resident peritoneal macrophages and brain macrophages. Conditioned media collected from tissue slices containing the axotomized central nervous system neurons exhibit BDCF activity. Initial experiments indicated that BDCF is a small peptide and, thus, we used specific pharmacologic reagents to characterize further BDCF activity. Naloxone, a pan opioid receptor antagonist, completely blocks BDCF activity. Although both kappa and mu opioid receptor antagonists failed to modify BDCF-induced macrophage chemotaxis, two specific delta receptor antagonists blocked BDCF. Analysis of BDCF by reverse phase HPLC and RIA revealed peak chemotactic activity in fractions consistent with the presence of an opioid peptide. The results suggest that cells in the brain respond to neuronal injury by producing and releasing opioids that can initiate a specific macrophage response.

Induction of opioid receptor-mediated macrophage chemotactic activity after neonatal brain injury

Macrophages have a prominent role in the injury response of the brain, yet the molecular mechanisms that control their invasion to the site of neuronal degeneration is unknown. After removal of the posterior cortex at birth, there is massive and specific targeting of nonresident macrophages to axotomized neurons in the lateral thalamus. The present study has identified an injury-induced, brain-derived chemotactic factor (BDCF) capable of eliciting chemotactic responses from resident peritoneal macrophages and brain macrophages. Conditioned media collected from tissue slices containing the axotomized central nervous system neurons exhibit BDCF activity. Initial experiments indicated that BDCF is a small peptide and, thus, we used specific pharmacologic reagents to characterize further BDCF activity. Naloxone, a pan opioid receptor antagonist, completely blocks BDCF activity. Although both kappa and mu opioid receptor antagonists failed to modify BDCF-induced macrophage chemotaxis, two specific delta receptor antagonists blocked BDCF. Analysis of BDCF by reverse phase HPLC and RIA revealed peak chemotactic activity in fractions consistent with the presence of an opioid peptide. The results suggest that cells in the brain respond to neuronal injury by producing and releasing opioids that can initiate a specific macrophage response.

Microdialysis reveals a morphine-induced increase in pallidal opioid peptide release

Freely moving rats were implanted with microdialysis probes in the globus pallidus/ventral pallidum, nucleus accumbens or caudate nucleus. Morphine (10 mg kg-1 i.p.) induced an average 128% increase in extracellular opioid peptide levels in the pallidum over a 2 h period peaking 1 h after injection. No change was observed in the nucleus accumbens or caudate nucleus. Dose-response analysis showed a smaller (26%), non-significant, increase at a lower dose of 2 mg kg-1 and no effect at a higher dose of 40 mg kg-1. No evidence of significant acute tolerance was apparent following repeated administration of morphine (10 mg kg-1, i.p.) at 3 h intervals. The magnitude of the morphine effect varied greatly between animals and was dependent on the pre-injection baseline opioid peptide levels.

Ca2+ channel and adenylyl cyclase modulation by cloned mu-opioid receptors in GH3 cells

Members of the three classes of opioid receptors (mu, delta, and kappa) have been cloned and characterized in unexcitable cell lines using biochemical techniques. However, an important function of these cloned receptors, their coupling to voltage-activated Ca2+ channels, remains untested. We stably transfected cloned rat mu-opioid receptor cDNAs into clonal pituitary GH3 cells. GH3 cells expressing mu-opioid receptors (GH3MOR cells) bound the receptor-specific ligands [D-Ala2,Me-Phe4,Gly-ol5]-enkephalin (DAMGO) and morphine with high affinity (Ki = 1.0 and 7.2 nM, respectively), and these ligands also potently inhibited adenylyl cyclase activity (IC50 = 21.9 and 55.2 nM, respectively). Functional coupling of mu-opioid receptors to voltage-activated Ca2+ channels was compared with that of endogenous somatostatin (SRIF) receptors in GH3MOR cells, using the patch-clamp technique, with Ba2+ as the charge carrier. DAMGO (1 microM) and SRIF (1 microM) inhibited Ba2+ currents by 23.8 +/- 1.0% and 22.9 +/- 2.5%, respectively. DAMGO (0.1 nM to 10 microM) dose-dependently inhibited Ba2+ currents, with an IC50 of 105 nM. The mu-opioid receptor agonist morphine (1 microM) inhibited currents by 13.5 +/- 1.1% and the delta-opioid receptor-selective ligand [D-Pen2,5]-enkephalin (1 microM) caused only 3.5 +/- 2.1% inhibition. The inhibitory actions of DAMGO, morphine, and [D-Pen2,5]-enkephalin were reversed by naloxone. Ba2+ current inhibitions by DAMGO and SRIF were attenuated by pertussis toxin pretreatment. Nimodipine reduced the amplitude of Ba2+ current inhibition by DAMGO, suggesting that mu-opioid receptors couple to L-type Ca2+ channels in GH3MOR cells.

Postpartum home care in the United States

Shorter postpartum hospital stays have increased the need for postpartum home care. Health-care reform in the United States must include postpartum follow-up care as a basic maternity benefit. This article explores the variety of options for postpartum home care, including telephone calls, home visits, information lines, lactation consultations, mother-infant outpatient clinics, support groups, and a model program for childbearing women in Washington state.

Preferential localization of a vesicular monoamine transporter to dense core vesicles in PC12 cells

Neurons and endocrine cells have two types of secretory vesicle that undergo regulated exocytosis. Large dense core vesicles (LDCVs) store neural peptides whereas small clear synaptic vesicles store classical neurotransmitters such as acetylcholine, gamma-aminobutyric acid (GABA), glycine, and glutamate. However, monoamines differ from other classical transmitters and have been reported to appear in both LDCVs and smaller vesicles. To localize the transporter that packages monoamines into secretory vesicles, we have raised antibodies to a COOH-terminal sequence from the vesicular amine transporter expressed in the adrenal gland (VMAT1). Like synaptic vesicle proteins, the transporter occurs in endosomes of transfected CHO cells, accounting for the observed vesicular transport activity. In rat pheochromocytoma PC12 cells, the transporter occurs principally in LDCVs by both immunofluorescence and density gradient centrifugation. Synaptic-like microvesicles in PC12 cells contain relatively little VMAT1. The results appear to account for the storage of monoamines by LDCVs in the adrenal medulla and indicate that VMAT1 provides a novel membrane protein marker unique to LDCVs.

Epidemiology of varicose veins. A review

Disease of the venous system is a major problem affecting western societies, resulting in considerable morbidity in the population and cost to the health service. In many countries "varicose veins are probably the commonest disorder presenting to general surgeons" and an average of 30% of district nursing time is estimated to be spent caring for patients with venous ulcers. For the patient with varicose veins or leg ulceration, there is often persistent discomfort and disability extending over long periods of time. Despite this, little epidemiological research has been carried out on venous disease, perhaps partly because of society's perception that venous disease is not a major problem and it is not normally a cause death. More recently however, efforts have been made to conduct structured epidemiological studies to identify risk factors and to clarify the geographical variations suggested in the past by anecdotal evidence. This article reviews recent epidemiological studies, discusses the prevalence of varicose veins and presents evidence for and against the differing theories of causation.

Ability of delta-opioid receptors to interact with multiple G-proteins is independent of receptor density

To determine whether the previously demonstrated ability of delta-opioid receptors to interact simultaneously with multiple G-proteins was a function of high receptor levels, this interaction was investigated in Chinese hamster ovary cells stably expressing 10 different levels of cloned delta-opioid receptors, ranging from 18,000 to 1.6 x 10(6) receptors/cell. The opioid agonist D-Ala2,D-Leu5-enkephalin (DADLE) inhibited forskolin-stimulated adenylyl cyclase activity in all 10 clones with variable maximal inhibitory levels. Furthermore, opioid agonists altered incorporation of [alpha-32P]azidoanilido-GTP into at least four G-protein alpha-subunits in all 10 clones, three of which were determined to be Gi3 alpha, Gi2 alpha and Go2 alpha. This effect was concentration-dependent, naloxone-reversible, and delta-opioid agonist-specific and was blocked by pretreatment with pertussis toxin. Although DADLE induced an increase in the incorporation of [alpha-32P]azidoanilido-GTP into three of the four G alpha proteins that was independent of receptor density, the magnitude of this response was greater as receptor density increased. In addition, concentrations of DADLE required to promote 50% maximal labeling were similar for all four G alpha proteins within each clone and did not appear to be affected by receptor density. Therefore, the ability of delta-opioid receptors to interact with multiple G-proteins is independent of receptor density and there is also no apparent correlation between the amount of G-protein activated and the maximal effect of an agonist.

Microdialysis reveals changes in extracellular opioid peptide levels in the amygdala induced by amygdaloid kindling stimulation

Enkephalins released in basolateral nucleus of the amygdala in response to electrical stimulation were determined in amygdala kindled and nonkindled freely moving rats using microdialysis. Enkephalin release was enhanced after a single and repetitive electrical stimulation (233 and 130% above control levels, respectively) in nonkindled rats. In fully kindled rats, the extracellular enkephalin levels decreased (35% below the control levels) within the first 20 min after onset of stage V kindled seizures, reaching baseline level 40 to 60 min following the generalized seizure activity. HPLC analysis identified the majority of recovered immunoreactive material from the amygdala as Met-enkephalin. On the basis of our results it is suggested that the enhanced enkephalin release in the amygdala during the early kindling stages might have a suppressive effect which may represent a homeostatic mechanism to avoid the spread of the afterdischarge to other structures. The decreased extracellular level of enkephalin in the amygdala after stage V kindled seizures could reflect a general impairment of inhibitory mechanisms in this structure with subsequent production of seizure activity.

Antipeptide antibodies against a Torpedo cysteine-string protein

An antipeptide antiserum was raised against the C-terminal undecapeptide of a Torpedo cysteine-string protein (csp), a putative subunit or modulator of presynaptic calcium channels. This antiserum was shown to identify selectively the 27-kDa in vitro translation product of the csp cRNA both by immunoprecipitation and on immunoblots. When affinity-purified anti-csp antibodies were used to probe immunoblots of membrane proteins from Torpedo electric organ or liver, specific immunoreactivity was detected only in electric organ. This immunoreactivity was associated principally with a single protein species of about 34 kDa. These results indicate that csp immunoreactivity is detectably expressed in electroplax, a heavily innervated tissue, but not in liver, which should have an appreciably lower abundance of presynaptic calcium channel proteins. Moreover, the increased relative molecular mass of csp in electric organ (compared with in vitro translated material) implies that csp is posttranslationally modified. Finally, immunoblot analysis of either intact, alkali-treated, or solubilized membrane fractions of electric organ reveals that csp is predominantly a membrane protein.

Absolute measurements of total-body calcium using prompt gamma neutron analysis and internal chlorine standardization: results in renal patients

Measurement of total-body calcium (TBCa) is important in the study of several medical conditions. Neutron activation analysis (NAA) is sufficiently precise for serial measurements, but in order to provide single, absolute determinations of TBCa, it requires a correction for body habitus. A method is described for the absolute determination of TBCa by comparing the total-body chlorine, obtained by NAA, with that obtained by stable bromine dilution. The method is applied to a group of thirty patients who had been treated for chronic renal failure, and significant differences are found between measured values of TBCa and those predicted for 'normal' healthy subjects. The overall experimental error in the absolute determination of TBCa is estimated to be 8%, for a dose equivalent of 3.1 mSv (based on skin dose, and a quality factor of 10 for neutrons).

A five-compartment model of body composition of healthy subjects assessed using in vivo neutron activation analysis

A body composition study of 31 healthy subjects covering a wide range of age (23.5-72.0 years) and weight (44.5-104.2 kg) has been undertaken. Subjects were assessed by in vivo neutron activation and tritiated water analysis and values of total body nitrogen, hydrogen and fat obtained by utilization of a five-compartment model of body composition comprising protein, water, fat, minerals and glycogen. The protein (as 6.25 x nitrogen) and water compartments were measured but the smaller compartments of minerals and glycogen were calculated as fixed fractions of the fat-free mass estimated from the water space. Fat was calculated as the body mass less the sum of the four other compartments. Mean values (+/- SEM), expressed as a percentage of body mass, for nitrogen, hydrogen and fat were 2.56 (+/- 0.07)%, 10.07 (+/- 0.04)%, and 21.9 (+/- 1.7)% respectively for men and 2.14 (+/- 0.07)%, 10.40 (+/- 0.04)%, and 35.5 (+/- 1.7)% respectively for women. The accuracy of the nitrogen measurements was evaluated by comparison with calculated values from two prediction equations; correlation coefficients, the mean bias (estimated from the mean differences between the measured and predicted nitrogen), the confidence interval for the bias, and limits of agreement were calculated. The correlation coefficients were high (r > 0.93) and the mean bias indicative of agreement. The ratio of nitrogen to the fat-free mass (derived from the body composition model) was also calculated and mean values (+/- SEM) of 32.7 (+/- 0.4) and 33.1 (+/- 0.4) g/kg for men and women, respectively were obtained. The hydration of the fat-free mass was determined to be 0.725 (+/- 0.002) and 0.722 (+/- 0.002) kg/kg for men and women respectively. The accuracy of the body fat estimate was evaluated by comparison with skinfold-thickness-derived values and computation from tritiated water space. The ratio of the body composition model to skinfold-thickness-derived fat was significantly (P < 0.005) greater than unity. The mean bias between the body composition model and tritiated-water-derived fat was -0.6 percentage points of fat (95% confidence interval from -0.3 to -0.9 percentage points of fat). Finally a prediction equation (r2 = 0.908, SEE = 108 g) for body nitrogen in healthy subjects based on weight, age and sex was calculated.