Site-directed alkylation of multiple opioid receptors. II. Pharmacological selectivity

A site-directed alkylating agent was used to inactivate one or more types of opioid receptor in two bioassay preparations in the presence of type-selective ligands as protectors of other opioid receptor types. Since the pharmacological potency of an agonist is decreased when the receptor type through which it acts has been inactivated, the method can be used to characterize the pharmacological selectivity of opioid agonists. All of the smaller opioid products of the enkephalin gene were found to be delta-selective in the mouse vas deferens, but BAM-12P, BAM- 22P , and Peptide E were not. In the same tissue, beta c-endorphin was not mu-selective, but in the guinea pig ileum preparation it evidently combined with mu and kappa receptors. The presence of functional epsilon receptors, however, could not be ruled out. The approach described here is applicable to any pharmacologically active receptors of which there are multiple types, and for which site-directed alkylating agents and type-selective protector ligands are available.

Analgesia induced by intrathecal injection of dynorphin B in the rat

A dose-dependent analgesic effect of intrathecally injected dynorphin B was observed in rats using the tail flick as nociceptive test. Intrathecal injection of 20 nmol of dynorphin B increased the tail flick latency by 90 +/- 23%, an effect that lasted about 90 min. For the same degree of analgesia, dynorphin B was 50% more potent than morphine on a molar basis. The analgesic effect of this dose of dynorphin B was partially blocked by 10 mg/kg, but not by 1 mg/kg, of subcutaneous naloxone, showing a relative resistance to naloxone reversal as compared with morphine analgesia. The analgesia produced by dynorphin B was unchanged in morphine-tolerant rats but was significantly decreased in rats tolerant to ethylketazocine. These results suggest that dynorphin B produces its potent analgesic effect by activation of kappa rather than mu opioid receptors in the rat spinal cord.

Plasma testosterone and luteinizing hormone levels during levo-alpha-acetylmethadol maintenance and withdrawal

Nine male heroin addicts maintained on L-alpha-acetylmethadol (LAAM) for about 5 mo had normal plasma levels of testosterone and luteinizing hormone 72 hr after a dose of LAAM and also during 2 wk after abrupt LAAM withdrawal.

Dynorphin converting enzyme with unusual specificity from rat brain

A rat brain membrane extract was shown to convert synthetic dynorphin B-29 ("leumorphin") to dynorphin B [dynorphin B-29-(1-13), "rimorphin"]. This represents a "single arginine cleavage" at Thr-Arg at positions 13 and 14 of the substrate. The product was identified by immunoprecipitation with a highly specific dynorphin B antiserum and by coelution with radiolabeled dynorphin B on reversed-phase high-performance liquid chromatography. The converting activity exhibits a pH optimum of 8. It is inhibited by a thiol protease inhibitor but not by inhibitors of cathepsin B or of serine proteases. It is inhibited by dynorphin A but not by various dynorphin A fragments. These results suggest that the converting activity is due to a novel thiol protease distinct from any known protease believed to function in the processing of biologically active peptides.

Opioid receptor selectivity of dynorphin gene products

In the guinea-pig ileum myenteric plexus-longitudinal muscle preparation, products from the dynorphin gene fell into three groups according to their potency. Dynorphin A was the most potent; dynorphin-32, dynorphin B, dynorphin B-29 and alpha-neo-endorphin were about equipotent and 10 to 20 times less potent than dynorphin A; dynorphin A-(1-8) and beta-neo-endorphin were about 200 times less potent than dynorphin A. Dynorphin A (a kappa agonist) was about 10 times less sensitive to antagonism by naloxone (as measured by naloxone Ke) than was normorphine (a mu agonist). Ke values for dynorphin-32, dynorphin B and alpha-neo-endorphin were the same as for dynorphin A, indicating that these peptides are also highly selective kappa agonists. Dynorphin A-(1-8), dynorphin B-29 and beta-neo-endorphin had Ke values intermediate between dynorphin A and normorphine, suggesting that they interact at both kappa and mu receptors. Addition of peptidase inhibitors to the bathing medium increased the potencies of dynorphin B, dynorphin B-29, alpha-neo-endorphin, dynorphin A-(1-8) and beta-neo-endorphin, but not of dynorphin A, dynorphin-32 or normorphine. The inhibitors did not change the naloxone Ke for dynorphin A or normorphine, or for dynorphin B-29, dynorphin A-(1-8) and beta-neo-endorphin, suggesting that the intermediate values were not caused by degradation to products with different receptor selectivities from the parent compounds. Ke for dynorphin-32, dynorphin B and alpha-neo-endorphin changed from being the same as dynorphin A in the absence of inhibitors to intermediate between dynorphin A and normorphine in the presence of inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)

No evidence for linkage between an insulin-dependent diabetes mellitus-susceptibility locus and immunoglobulin loci KM or GM

We studied 52 families having more than one member affected with insulin-dependent diabetes mellitus (IDDM) for linkage of an IDDM-susceptibility locus to the immunoglobulin loci KM and GM. Linkage was analyzed by the LOD score method using single-locus recessive and dominant models of IDDM inheritance, with penetrances of the disease-susceptible genotypes being dependent on age and reaching a maximum of 20% by age 40. We found no evidence for linkage of IDDM to KM or GM. Close linkage (recombination fraction less than 5%) was rejected for KM under the recessive model and for GM under both models. These results suggest either that there are no IDDM-susceptibility loci closely linked to KM or GM or that use of a single-locus model of IDDM (which ignores the effects of the susceptibility locus in the HLA region) is inadequate for their detection.

Effects of eight-hour naloxone infusions on human subjects

Twelve normal male volunteers received saline control, low-dose naloxone, and high-dose naloxone infusions during three weekly sessions. The sessions were 16 hr long: 1 hr for predrug assessments, 8 hr during which either naloxone or saline was infused in a double-blind procedure, and a 7-hr postdrug observation period. The 8-hr infusions of naloxone had no effect on experimental ischemic arm pain. In addition, the ischemic arm pain procedure did not significantly increase either plasma levels of cortisol or immunoreactive beta-endorphin, suggesting that the procedure was not stressful. The high-dose naloxone infusion resulted in a slightly aversive mood state and prevented the normal circadian decrease in cortisol levels. Both doses of naloxone increased systolic blood pressure and prevented the normal diurnal increase in temperature. The 8-hr infusions of naloxone did not result in changes in pain, mood, or physiological indices beyond what was present within a few hours after starting the infusion.

Regional distribution of dynorphin and neo-endorphin peptides in rat brain, spinal cord, and pituitary

Five products of the dynorphin gene--alpha-neo-endorphin, beta-neo-endorphin, dynorphin A, dynorphin A-(1-8), and dynorphin B--were measured in various regions of rat brain and in rat spinal cord and pituitary. Specific antisera were used, supplemented by gel permeation analysis and high performance liquid chromatography, confirming the presence of dynorphin-32, dynorphin A, and dynorphin B in rat brain. In whole brain, alpha-neo-endorphin, dynorphin A-(1-8), and dynorphin B are present in much greater amounts than beta-neo-endorphin or dynorphin A. Although a general parallelism was found in the distribution of the five peptides, there were also noteworthy exceptions, suggesting that differential processing may occur.

Methadyl acetate (LAAM) in the treatment of heroin addicts. II. Double-blind comparison of gradual and abrupt detoxification

One hundred nineteen patients were admitted to a six-month (26-week) prenaltrexone detoxification program comparing abrupt and gradual withdrawal from methadyl acetate (LAAM) therapy. All patients were brought to a maintenance level of 50, 50, and 65 mg (Monday, Wednesday, and Friday). Patients randomly assigned to the gradual group (group G) began 4-mg/wk reduction the Monday of week 9 and reached zero dosage (placebo) the Monday of week 23; patients in the abrupt group (group A) continued to receive 50, 50, and 65 mg until the Monday of week 23, when their dosage was dropped to zero (placebo). All patients were given placebo for four weeks. This study showed the superiority of abrupt withdrawal over this gradual-withdrawal schedule. Forty-six percent of group P compared with 28% of group G made the transition to naltrexone treatment. Severity of withdrawal problems was in no case significantly greater in group A.

Episodes of heroin use during maintenance treatment with stable dosage of (-)-alpha-acetylmethadol (methadyl acetate, LAAM)

The phenomenon of episodic heroin use by patients maintained on a surrogate opiate has been noted by clinical investigators since the early 1970s. Several investigators have hypothesized that relapse to heroin use is related to stressful events in the patient's life, and retrospective studies give some support to this hypothesis. In the present study, we asked patients every month to rate their situation with respect to 11 life areas. There were significant negative correlations between the absolute scores in most life areas and the amount of heroin use. However, the relationship between changes in life-area scores and changes in heroin use was less clear. Our data indicate that of patients who have substantial increases in heroin use, many do have negative changes in one or more life areas. However, not all patients who have such negative changes in life-area scores respond by increasing their heroin use.

Particle image-resolution test object

A blur definition and measurement technique for high-subject-contrast image resolution is proposed. A new test object utilizing the blur principle has been developed and feasibility tested. In developing this new test object, tests of various sizes and concentrations of small plastic particles in a gelatin base were performed. Optimum particle sizes and concentrations were selected for the popular clinical transducer frequencies. Test images were obtained with static and real-time transducers of various focal properties. In all cases the proposed test object clearly indicated the zone (focal zone) of optimum high-subject-contrast image resolution. The advantages of the proposed blur definition and measurement technique of high-subject-contrast image resolution include: test object simplicity, ease of performing and interpreting the measurement, usefulness for all types of real-time scanners, and the need for only one scan for both axial and lateral resolution information at all image depths.

[Lung injury after use of respiratory revival materials sterilized with ethylene oxide]

One of the most used method of medical appliances sterilization uses ethylene oxide. At high concentration, this very reactive product, causes caustic burns of skin and mucous membranes. In one case of acute pulmonary oedema, levels of ethylene oxide in the endotracheal catheter were discovered. This led us to review the toxicological data on this substance. It should be emphasized that the sterilization and the desorption according to simple and precise rules should prevent such acute accidents.

Pro-dynorphin peptides are found in the same neurons throughout rat brain: immunocytochemical study

It is known that the opioid peptide dynorphin A has a broad distribution throughout the neuraxis. Recent biochemical studies have extended the sequence of dynorphin A by 15 amino acids to include another [Leu]enkephalin-containing peptide known as dynorphin B. These sequence data have been validated by the elucidation of the structure of the hypothalamic mRNA coding for alpha- and beta-neo-endorphin, dynorphin A, and dynorphin B. Using specific antisera directed against each of the three opioid peptides, we have studied their cellular distribution in rat brain. Their distribution patterns are extremely similar, if not identical. Furthermore, all three peptide immunoreactivities can be localized to the same cells in five nuclear groups throughout the brainstem--the supraoptic nucleus, the paraventricular nucleus, a group of cells in the lateral hypothalamic area, the nucleus parabrachialis, and the nucleus tractus solitarius. The sequence of a common precursor for dynorphin A, B, and alpha- and beta-neo-endorphin was deduced from hypothalamic mRNA. The ability to localize all three peptides together within cells in widely placed nuclei strongly supports the use of the same biosynthetic precursor for the neo-endorphin and dynorphin peptides in other parts of the central nervous system as well.

Immunoreactive dynorphin in rat tissues and plasma

Distribution of immunoreactive dynorphin (ir-dyn) has been determined in rat tissues using a highly specific antiserum. Concentrations are highest in the pituitary, brain and spinal cord, as previously reported. In peripheral tissues highest levels occur in the stomach and upper intestine, but ir-dyn has also been detected in several other tissues, including heart and skeletal muscle. Unilateral vagotomy did not affect the amount of ir-dyn in heart or stomach, and denervation did not affect the amount in skeletal muscle. Gel permeation chromatography of the ir-dyn in gastrointestinal tract, heart, and skeletal muscle revealed a larger apparent molecular weight than that of the 17-residue dynorphin. Using octadecylsilyl-silica cartridges, it was possible to extract and concentrate ir-dyn from rat plasma. By gel permeation chromatography plasma immunoreactivity was found in two peaks, both of higher apparent molecular weight than dynorphin. This immunoreactivity was unaltered by hypophysectomy or adrenalectomy.

Dynorphin is contained within hippocampal mossy fibers: immunochemical alterations after kainic acid administration and colchicine-induced neurotoxicity

Antisera raised against synthetic dynorphin or [Leu5]enkephalin demonstrate immunostaining in hippocampal mossy fibers and in dentate granule cells. However, dynorphin immunoreactivity (ir) appears to be denser in immunocytochemical preparations and is quantitatively greater by radioimmunoassay than enkephalin-ir. Immunostaining with dynorphin antisera is eliminated by adsorption with 1-100 microM dynorphin-17 whereas immunostaining with enkephalin antisera is eliminated by adsorption with 1-100 microM [Leu5]enkephalin, dynorphin-17, dynorphin-(1-13), or alpha-neo-endorphin. Intrahippocampal colchicine injections, which selectively destroy dentate granule cells, significantly decrease the dynorphin-ir and enkephalin-ir levels in rat hippocampus. Intraventricularly administered kainic acid, which selectively destroys CA3-4 pyramidal cells, results in an increase of enkephalin immunostaining in mossy fibers and a significant increase in enkephalin-ir by radioimmunoassay in whole hippocampus. The enkephalin-ir cells and fibers in entorhinal/perirhinal cortex, which innervate rat hippocampus and dentate gyrus, do not contain dynorphin-ir.

Comparison of the distribution of dynorphin systems and enkephalin systems in brain

A study of the anatomical distribution of the endogenous opioid dynorphin in rat brain showed that the peptide is localized in a widespread system with multiple cell groups and projections. This network is revealed by the use of multiple antiserums against dynorphin and can be distinguished from the system containing methionine-enkephalin and leucine-enkephalin, which is mapped by the use of antiserums against the enkephalins and biosynthetically related peptides in the adrenal. It thus appears that the brain contains at least three separate opioid neuronal networks: an enkephalin family with components similar to those found in the adrenal, a beta-endorphin family, and a dynorphin family.

A specific radioimmunoassay for the opioid peptide dynorphin B in neural tissues

Dynorphin-32 was recently isolated from porcine pituitary and shown to consist of dynorphin A (the originally isolated dynorphin heptadecapeptide) at the amino terminus, followed by Lys-Arg (a putative signal for proteolytic cleavage) and then a tridecapeptide, dynorphin B, at the carboxyl terminus. Dynorphin B, like dynorphin A, contains leucine enkephalin. The present report describes and validates a radioimmunoassay for dynorphin B using an antiserum, "13S", that does not crossreact with other known opioid peptides. Immunoreactive dynorphin B was estimated in rat and porcine neural tissues and found to be 2-3 fold higher than reported values for dynorphin A. Distribution based on tissue concentration was similar to that of dynorphin A, with very high concentrations in neurointermediate pituitary. Small quantities of antiserum "13S" are available to investigators upon request.