PubMed Health⌕ Search

Biomedical subjects

George B Stefano

Publications and source records attributed to George B Stefano.

At least 19 recordsLinked to original sources
PubMed2006

Nitric oxide's pulsatile release in lobster heart and its regulation by opiate signaling: pesticide interference.

BACKGROUND: Data is emerging in the human and invertebrate literature demonstrating that mu opiate receptors and morphine are present in cardiovascular tissues in diverse animals, including human tissues, where they may be exerting a cardioregulatory role via stimulation of constitutive nitric oxide (NO) production. MATERIAL/METHODS: NO release from lobster heart was evaluated without stimulation and after morphine exposure using a real-time NO-specific amperometric probe. In addition, real time NO release was evaluated after treatment with low doses of widely used pesticides (e.g., pyrethroids). Real time RT-PCR was used to investigate the presence of mu opiate receptor subtypes in lobster heart. RESULTS: Basal NO release occurs in lobster heart at the nanomolar level. Morphine enhanced this level of release; naloxone (an opiate antagonist) blocked it, as did exposure to the NO synthase inhibitor L-NAME. In addition, treatment with the pyrethroids, permethrin and resmethrin, abrogated constitutive NO release from lobster heart. Finally, by way of real time RT-PCR we were able to demonstrate the presence of the micro(3) opiate receptor subtype in lobster heart. CONCLUSIONS: Rhythmic NO bursts appear to be involved in normal cardiac muscle activity in Homarus americanus. Lobster heart contains morphinergic signaling components capable of slowing down its beating rate via NO production. In addition, compounds such as pyrethroid pesticides may alter normal cardiac activity by interfering with constitutive NO production and thus, depressing basal NO levels. This may ultimately make these animals more susceptible to environmental assaults/toxins.

Animals↗
PubMed2006

De novo biosynthesis of morphine in animal cells: an evidence-based model.

Recent empirical findings have contributed valuable mechanistic information in support of a regulated de novo biosynthetic pathway for chemically authentic morphine in animal cells, with many similarities to the extensively characterized multi-enzyme plant pathway in opium poppy (Papaver somniferum). The present review elaborates an evidence-based model of cellular morphine expression that reflects a coalescence of these recent biochemical data with historical data gleaned from over thirty years of neurochemical/neuropharmacological investigation into the etiology and biological significance of dopamine (DA)-related heterocyclic conjugate molecules, termed tetrahydroisoquinoline (TIQ) or benzylisoquinoline (BIQ) alkaloids, and with outstanding work completed over the last decade that has elucidated biochemical and molecular bases of morphine and related isoquinoline alkaloid expression in plant systems. In essence, we are now afforded a rare window of opportunity to firmly establish essential biochemical linkages between plant and animal biosynthetic pathways that have been conserved throughout evolution.

Alkaloids↗
PubMed2006

Morphine regulates gill ciliary activity via coupling to nitric oxide release in a bivalve mollusk: opiate receptor expression in gill tissues.

BACKGROUND: Invertebrates express opiate receptors and synthesize opiate alkaloids such as morphine and morphine-6beta-glucuronide. Most of this work has been demonstrated in immune and neural tissues of various invertebrates. We hypothesized that morphinergic signaling may also take place in Mytilus edulis gill since they are innervated, in part, with dopamine nerves. MATERIAL/METHODS: Ciliary activity from excised gills was evaluated via stroboscopic synchronization of metachronal wave formation before and after drug exposure. Nitric oxide was determined in real-time via an amperometric probe following drug application. Real-time RT-PCR was performed on excised gill tissue to confirm the presence of the mu opiate receptor transcript. RESULTS: Incubation of M. Edulis excised gill filaments reveal spontaneously lateral cilia beating in a metachronal wave of about 600 beats per minute, which was significantly decreased by morphine in a concentration dependent and naloxone reversible manner. Exposure of the spontaneously beating cilia to SNAP, a nitric oxide donor, also diminished the beating rate in a concentration dependent manner. Exposing the cilia to L-NAME blocked the morphine induced cilio-inhibition, demonstrating that morphine was working to inhibit the cilia via NO. Furthermore, the gill tissue contained mu opiate receptor transcripts, which was mu3 in nature. CONCLUSIONS: As in mammals, opiate signaling is not confined to neural tissues. This report demonstrates the occurrence of opiate signaling for the first time in an invertebrate's respiratory tissue.

Animals↗
PubMed2006

Rethinking the opiate system? Morphine and morphine-6-glucuronide as new endocrine and neuroendocrine mediators.

Since the 80s, intrigued by presence of morphine precursors in some mammalian cells, different laboratories were able to characterize morphine and morphine precursors in animal tissues. Endogenous morphine studies continued during 90s and this alkaloid was successfully characterized from more organs and fluids of vertebrates, including brain, adrenal gland, heart, cerebrospinal fluid and urine. Then, in the last three years a high rate of publications dealing with this topic emerged, leading to a better understanding of the endogenous morphine system. In this regard, this article comment all the new data recently collected on this rising subject and replace the morphine and its derivative, morphine-6-glucuronide, in the mammalian physiology.

Animals↗
PubMed2006

Signaling pathway of morphine induced acute thermal hyperalgesia in mice.

Systemic administration of morphine induced a hyperalgesic response in the hot plate test, at an extremely low dose (1-10 microg/kg). We have examined in vivo whether morphine, at an extremely low dose, induces acute central hypernociception following activation of the opioid receptor-mediated PLC/PKC inositol-lipid signaling pathway. The PLC inhibitor U73122 and the PKC blocker, calphostin C, dose dependently prevented the thermal hypernociception induced by morphine. This effect was also prevented by pretreatment with aODN against PLCbeta3 at 2 nmol/mouse and PKCgamma at 2-3 nmol/mouse. Low dose morphine hyperalgesia was dose dependently reversed by selective NMDA antagonist MK801 and ketamine. This study demonstrates the presence of a nociceptive PLCbeta3/PKCgamma/NMDA pathway stimulated by low concentrations of morphine, through muOR1 receptor, in mouse brain. This signaling pathway appears to play an opposing role in morphine analgesia. When mice were treated with a morphine analgesic dose (7 mg/kg), the downregulation of PLCbeta3 or PKCgamma at the same aODN doses used for the prevention of the hyperalgesic effect induced, respectively, a 46% and 67% potentiation in analgesic response. Experimental and clinical studies suggest that opioid may activate pronociceptive systems, leading to pain hypersensitivity and short-term tolerance, a phenomenon encountered in postoperative pain management by acute opioid administration. The clinical management of pain by morphine may be revisited in light of the identification of the signaling molecules of the hyperalgesic pathway.

Analgesia↗
PubMed2006

Norlaudanosoline and nicotine increase endogenous ganglionic morphine levels: nicotine addiction.

1. Given the presence of morphine, its metabolites and precursors, e.g., norlaudanosoline, in mammalian and invertebrate tissues, it became important to determine if exposing normal excised ganglia to norlaudanosoline would result in increasing endogenous morphine levels. 2. Mytilus edulis pedal ganglia contain 2.2 +/- 0.41 ng/g wet weight morphine as determined by high pressure liquid chromatography coupled to electrochemical detection and radioimmunoassay. 3. Incubation of M. edulis pedal ganglia with norlaudanosoline, a morphine precursor, resulted in a concentration- and time-dependent statistical increase in endogenous morphine levels (6.9 +/- 1.24 ng/g). 4. Injection of animals with nicotine also increased endogenous morphine levels in a manner that was antagonized by atropine, suggesting that nicotine addiction may be related to altering endogenous morphine levels in mammals. 5. We surmise that norlaudanosoline is being converted to morphine, demonstrating that invertebrate neural tissue can synthesize morphine.

Animals↗
PubMed2006

Identification of morphine-6-glucuronide in chromaffin cell secretory granules.

We report for the first time that morphine-6-glucuronide, a highly analgesic morphine-derived molecule, is present in adrenal chromaffin granules and secreted from chromaffin cells upon stimulation. We also demonstrate that phosphatidylethanolamine-binding protein (alternatively named Raf-1 kinase inhibitor protein or RKIP) acts as an endogenous morphine-6-glucuronide-binding protein. An UDP-glucuronosyltransferase 2B-like enzyme, described to transform morphine into morphine-6-glucuronide, has been immunodetected in the chromaffin granule matrix, and morphine-6-glucuronide de novo synthesis has been characterized, demonstrating the possible involvement of intragranular UDP-glucuronosyltransferase 2B-like enzyme in morphine-6-glucuronide metabolism. Once secreted into the circulation, morphine-6-glucuronide may mediate several systemic actions (e.g. on immune cells) based on its affinity for mu-opioid receptors. These activities could be facilitated by phosphatidylethanolamine-binding protein (PEBP), acting as a molecular shield and preventing morphine-6-glucuronide from rapid clearance. Taken together, our data represent an important observation on the role of morphine-6-glucuronide as a new endocrine factor.

Alkaloids↗
PubMed2006

Alcohol-, nicotine-, and cocaine-evoked release of morphine from invertebrate ganglia: model system for screening drugs of abuse.

BACKGROUND: Invertebrates express regulatory receptors, transporters, and channels responsive to established drugs of abuse, many of which mediate their effects through catecholamine pathways. We hypothesized that invertebrate neural systems may serve as models by which to evaluate the interactive pharmacological effects of these agents. MATERIAL AND METHODS: Ex vivo pharmacological trials determined the effects of saturating levels of ethanol on morphine levels in pooled Mytilus edulis ganglia via HPLC coupled to electrochemical detection and/or HPLC/RIA analyses. Additional trials evaluated the ability of ethanol, nicotine, and cocaine, to promote evoked release of 125I-labeled morphine from neural tissues, because intrinsically low levels of morphine did not allow direct quantification of its release. RESULTS: Incubation of pooled M. edulis pedal ganglia with 200 mM ethanol (approximately 1% ethanol v/v) resulted in a two-fold increase in morphine concentration at 15 min, return to baseline at 30 min, and a 50% decrease in morphine concentration at 60 min. Separate incubations of pooled M. edulis pedal ganglia and H. americanus nerve cord with ethanol, cocaine, and nicotine resulted in a statistically significant enhancement of 125I-trace labeled morphine release. CONCLUSIONS: The stimulatory effects of ethanol, nicotine, and cocaine on cellular expression and release of endogenous morphine suggest convergent mechanisms underlying the reinforcing and addictive properties for a variety of drugs of abuse. The evolutionary conservation of L-tyrosine as a common precursor to catecholamine and opiate/opioid signaling systems may define a functional triad involving endogenous morphine, dopamine, and other classes of addictive drugs.

Animals↗
PubMed2006

Pain and relaxation (review).

The modern notion of pain and its clinical management, along with its physiological origins, is of exceeding interest to both clinicians and basic science researchers. While much is known about the control of pain via non-steroidal anti-inflammatory medications or comparative exogenous analgesics, little is known about the interplay between pain perception and its relationship with catecholamine molecules. We believe that the perception of pain and the body's self-attempt to alleviate it utilizing conventional homeostatic mechanisms via endogenous opiate release is mediated by key catecholamines, and that this effect is further modulated by nitric oxide. We further propose a new paradigm which links pain, endogenous opiates, and the catecholamines in a unique robust fashion demonstrating a complex symbiotic signaling system.

Animals↗
PubMed2006

Cholinergic regulation of endogenous morphine release from lobster nerve cord.

BACKGROUND: Invertebrate nervous systems are regulated by G-coupled protein receptors, chemical transporters, and ion channels responsive to established drugs of abuse including opiates, alcohol, psychostinulants, and nicotine. Thus, invertebrate nervous tissue preparations can be used as predictive model systems by which to evaluate underlying pharmacological mechanisms of addictive processes. MATERIAL/METHODS: Ex vivo pharmacological trials were used to determine the comparative effects of the nicotinic agonists and antagonists on the evoked release of labeled morphine from H. americanus nerve cord. The intrinsically low basal levels of endogenous morphine required that we utilize an ex vivo model system involving pre-labeling of intracellutlar opiate alkaloid pools with high specific activity 125I labeled morphine. RESULTS: Both nicotine and epibatidine promoted evoked release of 125I labeled morphine that is selectively linked to activation of invertebrate nicotinic receptors based on pharmacological inhibition by alpha bungarotoxin (alpha-BuTx). Epibatidine promoted release at concentrations 2-3 orders of magnitude higher than nicotine. Co-administration of nicotine (60 nM) and the pre-junctional ganglionic nicotinic antagonist hexamethonium (1 microM) produced a marked potentiation of 125I labeled morphine release; a pharmacological effect also observed for epibatidine (35 microM) co-administered with the competitive nicotinic antagonist chlorisondaminie at 1 microM. The stimulatory effects of ethanol to promote enhanced release of endogenous morphine were not affected by co-admninistration of alpha-BuTx at 1 microM. CONCLUSIONS: The stirmulatory effects of nicotine on cellular expression and release of endogenous morphine occurs via specific alpha-BuTx sensitive receptors, suggesting a novel mechanism underling the reinforcing and addictive properties of nicotine via endogenous morphine.

Animals↗
PubMed2006

Relaxation: molecular and physiological significance.

There appears to be a molecular process for relaxation. Given this, we attempt to demonstrate this phenomenon based on established molecular and physiological processes in light of our current understanding of central and peripheral nervous system mechanisms. Central to our hypothesis is the significance of norepinephrine, nitric oxide, dopamine and morphine signaling both in the central and peripheral nervous system. We find that nitric oxide and morphine control catecholamine processes on many levels, including synthesis, release and actions. We conclude that enough scientific information exists to support these phenotmena as actual physical processes that can be harnessed to provide better patient care.

Central Nervous System↗
PubMed2006

Alcohol-, nicotine-, and cocaine-evoked release of morphine from human white blood cells: substances of abuse actions converge on endogenous morphine release.

BACKGROUND: Normal human white blood cells (WBC) have the ability to synthesize morphine as do invertebrate ganglia. Furthermore, invertebrate neural tissues incubated with ethanol, cocaine, or nicotine results in a statistically significant enhancement of labeled morphine release. We now demonstrate that this also occurs with human WBC. MATERIAL/METHODS: Human blood was obtained from the Long Island Blood Services (Melville, NY). Polymorphonuclear cells (PMN) or mononuclear cells (MN) (10 million/ml) were bathed in phosphate buffered saline (PBS) medium containing purified RIA grade 125I-labeled morphine for trace labeling and quantification of media concentrations of morphine were via RIA. Cells were then incubated with cocaine, alcohol or nicotine and morphine release was determined. Residual levels of radioactivity in control tissues were always greater than 65% of total cpm, whereas in treated tissue differences depended on the amount of drug added. RESULTS: Incorporation rates of 125I-labeled morphine into PMN and MN were 7.85+/-0.36% and 1.42+/-0.19%, respectively. Separate incubations of PMN with ethanol, cocaine, or nicotine resulted in a statistically significant enhancement of 125I-labeled morphine released into the extracellular medium in a concentration dependent manner. CONCLUSIONS: These substances of abuse have been linked into a common pathway because of the common dopamine connection. Now, they are additionally linked because of their common effect on endogenous morphinergic processes. It is highly significant that these substances of abuse converge on a similar process, providing a mechanism to initiate their pleasure and addicting actions with continued frequent use.

Alcohols↗
PubMed2006

[Endocannabinoids as molecular instruments of health promotion].

UNLABELLED: Endocannabinoids may be a physiological model for our self-healin capacities, since they are part of a complex system of natural auto-regulatory processes. This system has been examined via neurobiology, where the experimental invertebrate model is useful. Endocannabinoids, as well as endogenous morphine, activate constitutive nitric oxide (NO) release, which exerts a variety of positive physiological effects. By doing so, we surmise endogenous stress reduction emerges. Therefore, in the context of endocannabinoid auto-regulation, it seems adequate to speak of "health promotion on a molecular level". The convergence of endogenous auto-regulation on NO pathways critically relies upon common or overlapping neurobiological molecular components, as they are represented by limbic reward and motivation mechanisms. To our knowledge, endogenous auto-regulation--involving deep limbic brain activities--plays a crucial role in successful modern strategies of applied and integrative health promotion. More research, however, is necessary before the different aspects of neurobiological science and clinical medicine in the field of prevention may be integrated extensively and with profound reason. CONCLUSIONS: Successful preventive programs, such as integrative medical stress management, include auto-regulative mechanisms on the physiological level. This leads to an interesting research potential, particularly when one considers the long-term effects of applied health promotion and its coupling to motivational neurobiological phenomena.

Amino Acid Sequence↗
PubMed2005

Association between oxygen consumption and nitric oxide production during the relaxation response.

BACKGROUND: Mind/body practices that elicit the relaxation response (RR) are currently practiced by over 30% of American adults. RR elicitation reduces volumetric oxygen consumption (VO(2)) from rest and counteracts the effects of stress, although the mechanisms mediating the RR remain unknown. This study was designed to investigate whether RR elicitation is mediated by nitric oxide (NO). We developed a method to quantify depth of RR using change in VO(2) (slope) during RR elicitation. We evaluated whether depth of RR elicitation was correlated with changes in NO, as measured by percentage changes in fractional exhaled nitric oxide (F(E)NO). MATERIAL/METHODS: We conducted a randomized, controlled trial, in which 46 subjects were randomized to either 8-weeks of RR training using audiotapes (n=34) or 8-weeks of exposure to a control condition--receiving health-education by audiotapes (n=12). Prior to randomization, VO(2) and F(E)NO were measured while subjects listened to a control audiotape. Eight weeks later, VO(2) and F(E)NO were measured while the RR group listened to a RR-eliciting audiotape and the control group listened to a control audiotape. RESULTS: Prior to receiving any training, there was no association between VO(2) slope and F(E)NO. After training, there was an inverse correlation between VO(2) slope and F(E)NO in the RR group (r = -0.41, P=0.037, n=26), but not in the control group (r=0.12, P=0.78, n=8). CONCLUSIONS: Depth of RR elicitation was associated with increased concentrations of F(E)NO after RR training. The RR may be mediated by NO helping to explain its clinical effects in stress-related disorders.

Adult↗
PubMed2005

Human white blood cells synthesize morphine: CYP2D6 modulation.

Human plasma contains low, but physiologically significant, concentrations of morphine that can increase following trauma or exercise. We now demonstrate that normal, human white blood cells (WBC), specifically polymorphonuclear cells, contain and have the ability to synthesize morphine. We also show that WBC express CYP2D6, an enzyme capable of synthesizing morphine from tyramine, norlaudanosoline, and codeine. Significantly, we also show that morphine can be synthesized by another pathway via l-3,4-dihydroxyphenylalanine (L-DOPA). Finally, we show that WBC release morphine into their environment. These studies provide evidence that 1) the synthesis of morphine by various animal tissues is more widespread than previously thought and now includes human immune cells. 2) Moreover, another pathway for morphine synthesis exists, via L-DOPA, demonstrating an intersection between dopamine and morphine pathways. 3) WBC can release morphine into the environment to regulate themselves and other cells, suggesting involvement in autocrine signaling since these cells express the mu3 opiate receptor subtype.

Base Sequence↗
PubMed2005

Rapid stress reduction and anxiolysis among distressed women as a consequence of a three-month intensive yoga program.

BACKGROUND: Emotional distress is an increasing public health problem and Hatha yoga has been claimed to induce stress reduction and empowerment in practicing subjects. We aimed to evaluate potential effects of Iyengar Hatha yoga on perceived stress and associated psychological outcomes in mentally distressed women. MATERIAL/METHODS: A controlled prospective non-randomized study was conducted in 24 self-referred female subjects (mean age 37.9+/-7.3 years) who perceived themselves as emotionally distressed. Subjects were offered participation in one of two subsequential 3-months yoga programs. Group 1 (n=16) participated in the first class, group 2 (n=8) served as a waiting list control. During the yoga course, subjects attended two-weekly 90-min Iyengar yoga classes. Outcome was assessed on entry and after 3 months by Cohen Perceived Stress Scale, State-Trait Anxiety Inventory, Profile of Mood States, CESD-Depression Scale, Bf-S/Bf-S' Well-Being Scales, Freiburg Complaint List and ratings of physical well-being. Salivary cortisol levels were measured before and after an evening yoga class in a second sample. RESULTS: Compared to waiting-list, women who participated in the yoga-training demonstrated pronounced and significant improvements in perceived stress (P<0.02), State and Trait Anxiety (P<0.02 and P<0.01, respectively), well-being (P<0.01), vigor (P<0.02), fatigue (P<0.02) and depression (P<0.05). Physical well-being also increased (P<0.01), and those subjects suffering from headache or back pain reported marked pain relief. Salivary cortisol decreased significantly after participation in a yoga class (P<0.05). CONCLUSIONS: Women suffering from mental distress participating in a 3-month Iyengar yoga class show significant improvements on measures of stress and psychological outcomes. Further investigation of yoga with respect to prevention and treatment of stress-related disease and of underlying mechanism is warranted.

Adult↗