Systemic effects of E-2078, a stabilized dynorphin A(1–8) analog, in rhesus monkeys

  Rationale: E-2078 ([N-methyl-Tyr¹, N-methyl-Arg⁷, d-Leu⁸] dynorphin A(1–8) ethylamide) is a dynorphin A(1–8) analog with a reduced tendency to be biotransformed, when compared to the unmodified opioid peptide. E-2078 has been found to produce κ-opioid agonist effects in vivo in rodents. Objective: In the present studies, we investigated whether systemically administered E-2078 could produce κ-agonist effects in rhesus monkeys, in tests of antinociception, diuresis and ethylketocyclazocine (EKC) discrimination. Methods: E-2078 (0.32–18 mg/kg, SC, IM or IV) was tested in the warm water (50°, 55°C) tail withdrawal assay of thermal antinociception. The diuretic effects of E-2078 (0.056– 1.8 mg/kg, SC) were also compared to those of the κ-agonist, U69,593 (0.01–0.32 mg/kg, SC). Lastly, the effects of E-2078 (0.1–3.2 mg/kg, SC or IV) were studied in rhesus monkeys trained to discriminate EKC (0.0056 mg/kg SC) from vehicle, in a food-reinforced operant procedure. Results: E-2078 did not produce thermal antinociception in rhesus monkeys following SC or IM administration, up to the largest doses presently studied (i.e., 18 and 10 mg/kg, respectively). E-2078 caused thermal antinociception by the IV route, but this effect was not apparently mediated by κ- or μ-opioid receptors, as shown by its insensitivity to quadazocine (1 mg/kg) pretreatment. However, SC E-2078 caused diuresis, and this effect was blocked by quadazocine pretreatment, consistent with mediation by κ-opioid receptors. E-2078 generalized in EKC-discriminating monkeys, but only after the largest dose (3.2 mg/kg), and only following IV administration. Conclusions: The present studies suggest that systemically administered E-2078 can produce some κ-receptor mediated effects in rhesus monkeys, but its profile of action is not identical to non-peptidic κ-agonists following all routes of administration, or across all experimental situations. Received: 5 August 1998 / Final version: 6 November 1998     

Self-administration of fentanyl, cocaine and ketamine: effects on the pituitary–adrenal axis in rhesus monkeys

Rationale Drugs of abuse can affect the functioning of the hypothalamic–pituitary–adrenal (HPA) axis. Acute administration of drugs that serve as reinforcers have been observed to stimulate the rat HPA axis, leading to the suggestion that these stimulatory effects may contribute to the development of drug-maintained behaviors.Objectives To determine whether reinforcing drugs that are dissimilar with respect to their mechanisms of action have similar effects on HPA axis activity at doses that are self-administered. Rhesus monkeys were randomly assigned to self-administer the -opioid agonist fentanyl, the psychomotor stimulant cocaine, or the NMDA antagonist ketamine.Methods Each monkey was trained to press a lever in order to receive an intravenous injection of drug or saline. Blood samples were obtained before, during, and after the self-administration sessions and assayed for ACTH and cortisol by radioimmunoassay.Results Fentanyl, cocaine, and ketamine were each self-administered across a range of doses. However, the three drugs differed in their effects on ACTH and cortisol. Cocaine stimulated ACTH and cortisol secretion, a finding that is consistent with previous rat and primate studies. Self-administration of both fentanyl and ketamine inhibited HPA axis activity. HPA inhibition by fentanyl is consistent with other monkey and human studies, and contrasts with the stimulatory effects of -opioids in rodents. The inhibitory effect of ketamine on ACTH and cortisol secretion contrasts with findings in the few primate studies that have evaluated NMDA antagonists. Neither fentanyl nor cocaine, at doses that maintained maximum rates of responding, produced significant changes in ACTH and cortisol levels.Conclusions There appears to be little commonality between different classes of abused drugs and their effects on the HPA axis, which calls into question the necessity for HPA axis stimulation in the reinforcement of drug-maintained behavior.Results from this paper were first presented at the annual meeting of CPDD, Scottsdale, Ariz., USA, in June 2001.     

Self-administration of methohexital,midazolam and ethanol: effects on the pituitary–adrenal axis in rhesus monkeys

Rationale There is disagreement in the literature with respect to how drugs of abuse affect the functioning of the hypothalamic–pituitary–adrenal (HPA) axis, and whether these changes in endocrine function may be related to the rewarding effects of these drugs.Objectives To determine whether reinforcing drugs with different mechanisms of action affect HPA axis function at doses at which they serve as reinforcers.Methods Seven monkeys (6 male) were randomly assigned to self-administer methohexital—a barbiturate (n=4), midazolam—a benzodiazepine (n=3), or ethanol (n=5). Each monkey had a surgically implanted indwelling venous catheter, and was trained to respond on a fixed ratio of 30 lever presses to receive an injection of drug or saline. Blood samples were obtained before, during, and after the self-administration sessions for the measurement of ACTH and cortisol by radioimmunoassay.Results Although methohexital, midazolam, and ethanol all maintained self-administration behavior across a range of doses, they differed in their effects on ACTH and cortisol. Ethanol inhibited ACTH and cortisol secretion. Methohexital and midazolam both tended to decrease ACTH and cortisol at large doses, and increase these hormones at small doses, but the HPA effects of neither drug differed significantly from when saline was available.Conclusions The neutral overall effect of methohexital and midazolam on HPA activity is consistent with other monkey and human studies, whereas the inhibitory effect of self-administered ethanol in the monkey contrasts with both the rat and human literature. The data in this study suggest that a change in HPA axis activity is not a requirement for drug-reinforced behavior in monkeys.Results from this paper were first presented at the annual meeting of ISPNE, Quebec City, Canada, in August 2001.     

Effects of peptidase inhibitors on anti-nociceptive action of dynorphin-(1–8) in rats

Previous in vitro studies showed that the degradation of dynorphin-(1-8) [dyn-(1-8)] by cerebral membrane preparations is almost completely prevented by a mixture of three peptidase inhibitors (PIs), amastatin, captopril and phosphoramidon. In the present investigations, effects of the three PIs on the anti-nociception induced by the intra-third-ventricular (i.t.v.) administration of dyn-(1-8) were examined. The inhibitory effect of dyn-(1-8) on the tail-flick response was increased more than 100-fold by the i.t.v. pretreatment of rats with the three PIs. The inhibition produced by dyn-(1-8) in rats pretreated with any combination of two PIs was significantly smaller than that in rats pretreated with three PIs, indicating that any residual single peptidase could inactivate significant amounts of dyn-(1-8). The antagonistic effectiveness of naloxone, a relatively selective mu-opioid antagonist, indicates that dyn-(1-8)-induced inhibition of tail-flick response in rats pretreated with three PIs is mediated by mu-opioid receptors. Furthermore, mu-receptor-mediated inhibition induced by dyn-(1-8) was significantly greater than that produced by [Met5]-enkephalin in rats pretreated with three PIs. The data obtained in the present investigations together with those obtained in previous studies strongly indicate that dyn-(1-8) not only has well-known kappa-agonist activity but also has high mu-agonist activity.     

Effects of theα-glucosidase inhibitor 1 desoxynojirimycin (BAY M 1099) on postprandial blood glucose,serum insulin and C-peptide levels in type II diabetic patients

Summary Bay m 1099 is a newly developed inhibitor of intestinal-glucosidase. Its ability to lower postprandial plasma glucose, serum insulin and C-peptide levels in Type II diabetics has been investigated. Fifteen obese Type II diabetic patients with inadequate metabolic control during sulphonylurea treatment received a standardized diet and were treated either with Bay m 1099, b.d. (100 mg before breakfast and dinner) or placebo for 3 days, according to a double-blind cross-over design. The postprandial blood glucose level was significantly lower during Bay m 1099 treatment compared to placebo after breakfast and dinner (AUC after breakfastp<0.001). The reduced postprandial hyperglycaemia was associated with a decrease in meal stimulated serum insulin and C-peptide levels. Thus, Bay m 1099 may be a useful addition in the treatment of Type II diabetic patients.     

Effect of the endogenous κ opioid agonist dynorphin A(1–17) on cocaine-evoked increases in striatal dopamine levels and cocaine-induced place preference in C57BL/6J mice

Rationale Effects of synthetic kappa opioid receptor agonists on cocaine-induced reward have been studied extensively in rats but relatively few studies have used the endogenous kappa agonist dynorphin A(1–17).Objectives Three studies were conducted to examine the effect of the natural sequence dynorphin on cocaine-induced increases in dopamine, on the formation of conditioned place preference and on increases in locomotor activity in C57BL/6 J mice.Methods After implantation of guide cannulae into the caudate putamen, mice were allowed 4–5 days to recover from surgery. In the first study, dynorphin A (0, 1, 2, 4.4 nmol) was infused into the caudate putamen and dopamine levels were measured by in vivo microdialysis in that brain region. Then, the effect of dynorphin A (4.4 nmol) on increases in dopamine levels induced by 15 mg/kg cocaine i.p. was also measured with in vivo microdialysis. The third experiment examined the effect of dynorphin A (4.4 nmol) on conditioned place preference and locomotion induced by 15 mg/kg cocaine.Results Dynorphin A significantly decreased basal dopamine levels in a dose-dependent manner by more than 60% at the highest dose, and this effect was completely blocked by pre-injection of the kappa-opioid receptor antagonist nor-BNI (10 mg/kg). The highest dose of dynorphin (4.4 nmol) blocked increases in dopamine levels, the formation of conditioned place preference and attenuated locomotion induced by 15 mg/kg cocaine.Conclusion The blockade of the cocaine-induced rise in striatal dopamine may contribute to both dynorphins ability to prevent the development of cocaine-induced conditioned place preference and to attenuate the increase in locomotor activity.     

Protective Effects of 1-Methylnicotinamide on Aβ1–42-Induced Cognitive Deficits,Neuroinflammation and Apoptosis in Mice

Journal of Neuroimmune Pharmacology - The neurotoxicity of Aβ peptides has been well documented, but effective neuroprotective approaches against Aβ neurotoxicity are unavailable. In the...     

Effects of biomass combustion smoke on hematological and antioxidant profile among children (8–13 years) in India

The use of solid biomass fuel in traditional stoves has been associated with respiratory symptoms of chronic airway inflammation and higher rates of respiratory infections. The mechanisms of such associations remain unclear. In this study we examine the association between exposures to indoor pollution and the hematological and antioxidant profile in children. We found increases in the respiratory symptoms “cough without cold” [odds ratio (OR) 4.27; 95% confidence interval (CI) 3.00–4.95], “cough in the morning” (OR 3.80; CI 2.40–5.15), and “wheeze” (OR 3.60; CI 2.75–5.0) in children living in homes used solid biomass for cooking after adjustment for potential confounder variables. Children who lived in the households that cook with traditional biomass fuels had low hemoglobin and red blood cell (RBC) values, but raised white blood cell (WBC), neutrophil, and eosinophil counts. Furthermore, we examined the ascorbic acid, superoxide dismutase (SOD), and glutathione/oxidized glutathione (GSH/GSSG) ratio levels in the blood of the subjects and observed low levels of ascorbic acid (AA), SOD, and GSH/GSSG ratio in children lived in biomass used households. These findings suggest that the biomass smoke has the potential to produce oxidative stress and adverse health effects in children. There is much more work needed to confirm our conclusions. Investigating the mechanisms underlying air pollution-induced health problems would allow a more targeted approach to remove the most toxic components of air pollution, and could possibly provide a means to decrease individual sensitivity to air pollution.     

Effects of stress modulation on morphine-induced conditioned place preferences and plasma corticosterone levels in Fischer, Lewis, and Sprague–Dawley rat strains

Rationale There is a direct relationship between hypothalamic–pituitary–adrenal axis (HPA) reactivity and susceptibility to drug use in outbred rats. Specifically, manipulations that increase or decrease HPA activity also increase or decrease drug intake, respectively. Interestingly, this relationship has not been established in the inbred Fischer (F344) and Lewis (LEW) rat strains that are often used as animal models of susceptibility to drug use.Objective The present study investigated the effects of manipulations known to affect HPA activity on morphine-induced conditioned place preference (CPP) in male LEW, F344, and Sprague–Dawley (SD) rats.Materials and methods In experiment 1, animals were exposed to an injection of methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM) and 2-h restraint stress prior to the conditioning of a morphine-induced place preference (1, 4, or 10 mg/kg subcutaneous). In experiment 2, animals were chronically exposed to corticotropin-releasing hormone type 1 receptor antagonist, antalarmin, prior to CPP training. The effects of DMCM/restraint and antalarmin on corticosterone levels were examined in experiments 3 and 4.Results In outbred rats, DMCM/restraint increased both HPA activity and morphine-induced CPP, while antalarmin decreased CPP and produced a slight, but nonsignificant, decrease in corticosterone levels. In the inbred rats, however, DMCM/restraint increased plasma corticosterone yet decreased place preferences in the LEW strain, and antalarmin treatment decreased plasma corticosterone but increased place preferences in the F344 strain.Conclusions These data suggest that the relationship between stress and drug use may be nonmonotonic. The use of these inbred strains in genetic analysis of drug addiction may require reexamination.     

Effects of tamoxifen, 17α-ethynylestradiol, flutamide, and methyltestosterone on plasma vitellogenin levels of male and female Japanese medaka (Oryzias latipes)

The effects of oral administration of tamoxifen, 17α-ethynylestradiol (EE2), flutamide, and methyltestosterone (MT), on plasma vitellogenin levels of male and female medaka were investigated. Medaka were fed diets containing different concentrations of these chemicals for 7 days, and these plasma vitellogenin levels were measured. Tamoxifen increased significantly the vitellogenin levels in male, but inhibited the normal vitellogenin induction in female in the high concentration groups. EE2 increased significantly vitellogenin levels in both sexes. Flutamide increased significantly the vitellogenin levels in female, but gave no effects on male. MT inhibited the normal vitellogenin induction in female, but increased slightly vitellogenin levels in male without a clear tendency. Administration of tamoxifen, EE2, flutamide, and MT showed the different pattern in vitellogenin levels in both sexes.     

Physical dependence of a dermorphin tetrapeptide analog, [D-Arg2, Sar4]-dermorphin (1–4) in the rat

The characteristics of an analog of tetrapeptide dermorphin (H-Tyr-D-Arg-Phe-Sar-OH), [D-Arg², Sar⁴]-dermorphin (1–4) were examined in comparison with morphine by the appearance of typical withdrawal signs upon cessation of administration or treatment with naloxone, an opioid antagonist. The dose of [D-Arg², Sar⁴]-dermorphin (1–4) or morphine in the physical dependence test can be quantified by determining the ED₅₀ to inhibit the tail-flick response to thermal stimuli. Doses from 8 to 64 times the ED₅₀ doses were employed in the subcutaneous injection schedules. The cessation of [D-Arg², Sar⁴]-dermorphin (1–4) or naloxone treatment was largely without effect on body weight, in contrast to a marked loss of weight in morphine-dependent rats. The tetrapeptide failed to substitute for morphine in morphine-dependent rats. The physical dependence of [D-Arg², Sar⁴]-dermorphin (1–4) was revealed by the behavioral signs of withdrawal precipitated by naloxone. However, the scores of lacrimation, diarrhea and urination were much lower in chronically tetrapeptide-treated rats than in morphine-treated rats, though the score of teeth chatter was higher. These findings indicate that [D-Arg², Sar⁴]-dermorphin (1–4) may differ from morphine in physical dependence.     

Metabolism of a neurotensin (8–13) analog by intestinal and nasal enzymes,and approaches to stabilize this peptide at these absorption sites

Adamantoyl-Lys-Pro-Tyr-Ile-Leu (Ada-KPYIL) is a neurotensin analog which has analgesic activity when dosed parenterally, but not when dosed orally. In vitro studies were carried out to determine whether metabolism was responsible for oral inactivity. Ada-KPYIL was stable in simulated gastric fluid containing pepsin at acidic pH. Ada-KPYIL was immediately metabolized in simulated intestinal fluid containing pancreatin, a mixture of pancreatic enzymes, and also in dilute solutions containing this enzyme. Chymotrypsin, trypsin, elastase, and carboxypeptidase were each capable of metabolizing Ada-KPYIL, and chymotrypsin was active at the lowest concentration. Chymostatin effectively inhibited Ada-KPYIL metabolism by chymotrypsin. Formulation of Ada-KPYIL in mixed micelles or in an oil-in-water emulsion also inhibited metabolism by chymotrypsin. However, there was no inhibition of metabolism in a solution containing only the bile salt, suggesting that partitioning of Ada-KPYIL into the oil phase is the protective mechanism. Ada-KPYIL was stable when perfused through a rat nasal cavity. These oral formulation approaches or nasal administration may be useful for improving the delivery of Ada-KPYIL or other peptides with similar delivery problems.     

Correction to: The effect of glutamine supplementation on serum levels of some inflammatory factors,oxidative stress,and appetite in COVID-19 patients: a case–control study

Inflammopharmacology -     

Differential effects of acute and chronic treatment with the α2-adrenergic agonist,lofexidine, on cocaine self-administration in rhesus monkeys

Background

Lofexidine, an α₂-adrenergic agonist, is being investigated as a treatment for reducing opioid withdrawal symptoms and blocking stress-induced relapse to cocaine taking. Opioid abusers are often polydrug abusers and cocaine is one frequent drug of choice. However, relatively little is known about lofexidine interactions with cocaine. The present study investigated the effects of acute and chronic treatment with lofexidine in a pre-clinical model of cocaine self-administration.

Methods

Male rhesus monkeys were trained to respond for food (1 g) and cocaine (0.01 mg/kg/injection) under a fixed ratio 30 (FR30) or a second order FR2 (VR16:S) schedule of reinforcement. Systematic observations of behavior were conducted during and after chronic treatment with lofexidine.

Results

Acute treatment with lofexidine (0.1 or 0.32 mg/kg, IM) significantly reduced cocaine self-administration but responding for food was less effected. In contrast, chronic treatment (7–10 days) with lofexidine (0.1–0.32 mg/kg/h, IV) produced a leftward shift in the cocaine self-administration dose–effect curve, but had no effect on food-maintained responding. Lofexidine did not produce any observable side effects during or after treatment.

Conclusions

Lofexidine potentiated cocaine's reinforcing effects during chronic treatment. These data suggest that it is unlikely to be effective as a cocaine abuse medication and could enhance risk for cocaine abuse in polydrug abusers.     

Effects of anthocyanins on the AhR–CYP1A1 signaling pathway in human hepatocytes and human cancer cell lines

Anthocyanins are plant pigments occurring in flowers and berry fruits. Since a phenomenon of food–drug interactions is increasingly emerging, we examined the effects of 21 major anthocyanins and the extracts from 3 food supplements containing anthocyanins on the aryl hydrocarbon receptor (AhR)–cytochrome P450 CYP1A1 signaling pathway in human hepatocytes and human hepatic HepG2 and intestinal LS174T cancer cells. Pelargonidin-3-O-rutinoside (PEL-2) and cyanidin-3,5-O-diglucoside (CYA-3) dose-dependently activated AhR, as revealed by gene reporter assay. PEL-2 and CYA-3 induced CYP1A1 mRNA but not protein in HepG2 and LS174T cells. Neither compounds induced CYP1A1 mRNA and protein in four different primary human hepatocytes cultures. The effects of PEL-2 and CYA-3 on AhR occurred by ligand-dependent and ligand-independent mechanisms, respectively, as demonstrated by ligand binding assay. In a direct enzyme inhibition assay, none of the antocyanins tested inhibited the CYP1A1 marker activity to less than 50% even at 100 μM concentration. PEL-2 and CYA-3 at 100 μM inhibited CYP1A1 to 79% and 65%, respectively. In conclusion, with exception of PEL-2 and CYA-3, there were no effects of 19 major anthocyanins and 3 food supplements containing anthocyanins on AhR–CYP1A1 signaling, implying zero potential of these compounds for food–drug interactions with respect to AhR–CYP1A1 pathway.     

Organochlorine pollutants’ levels in hair,amniotic fluid and serum samples of pregnant women in Greece. A cohort study

Persistent organic pollutants are synthetic chemicals highly resistant to degradation with strong tendency to bioaccumulation. Assessment of human exposure to these compounds is crucial for public health protection, especially during vulnerable periods.The aim of the present cohort study was to evaluate the level of contamination to PCBs, o,p’- and p,p’-DDE, o,p’ and p,p’-DDD, o,p’ and p,p’-DDT and HCB in pregnant women. Hair, amniotic fluid and serum samples were collected and analyzed by HS-SPME-GCMS.The most detected analytes in amniotic fluids were p,p’-DDE, p,p’-DDD, o,p’-DDE and PCB101, in serum p,p’-DDE, HCB and PCB101 and in hair p,p’-DDE, HCB and PCB101. The levels of HCB and PCB101 in amniotic fluids were positively correlated with those in hair. Higher levels of DDDs and DDTs in hair samples and PCB28 in amniotic fluids were observed in smoker pregnant women. Gestation age was inversely proportional with the detected levels of PCB101 in all tested samples.     

Effects of intraplantar nocistatin and (±)-J 113397 injections on nociceptive behavior in a rat model of inflammation

Nocistatin (NST) and Nociceptin/Orphanin FQ (N/OFQ) are derived from the same precursor protein, pre-proN/OFQ, and exert opposite effects on the modulation of pain signals. However, the role of the peripheral N/OFQ and the NOP receptor, which is located at the endings of sensory nerves, in inflammatory pain was not ascertained. NST administered intrathecally (i.t.) prevented the nociceptive effects induced by i.t. N/OFQ and PGE₂. Moreover an up regulation of N/OFQ was shown in the rat in response to peripheral inflammation. Here, we investigated the effects of intraplantar (i.pl.) administration of functional N/OFQ and NOP receptor antagonists in a rat model of inflammatory pain. Our findings showed that i.pl. injection of (±)-J 113397, a selective antagonist of the NOP receptor, and NST, the functional N/OFQ antagonist, prior to carrageenan significantly reduced the paw allodynic and thermal hyperalgesic threshold induced by the inflammatory agent. The resulting antiallodynic and antihyperalgesic effects by co-administering NST and (±)-J 113397 prior to carrageenan were markedly enhanced, and the basal latencies were restored. Thus, it is likely that the peripheral N/OFQ/NOP receptor system contributes to the abnormal pain sensitivity in an inflammatory state.