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Biomedical subjects

F Porreca

Publications and source records attributed to F Porreca.

At least 181 records · Page 10Linked to original sources
PubMed1993

Differential antagonism of bremazocine- and U69,593-induced antinociception by quadazocine: further functional evidence of opioid kappa receptor multiplicity in the mouse.

In these studies, the antagonistic actions of (-)-1-Cyclopentyl-5-(1,2,3,4,5,-hexahydro-8-hydroxy-3,6,11-trimethyl-2,6 -methano-3-benzazocin-11-yl)-3-pentanone methanesulfonate (quadazocine) were evaluated against the kappa-receptor-mediated antinociceptive effects of i.c.v. (5 alpha, 7 alpha, 8 beta)-(+)-N-methyl-N-(7-(1-pyrrolidinyl)- 1-oxaspiro(4,5)dec-8-yl)benzeneacetamide (U69,593) or bremazocine in the mouse warm water tail-flick test. Quadazocine produced no antinociceptive effects alone, and it selectively antagonized the actions of bremazocine, but not U69,593, in a dose- and time-related fashion, supporting previous suggestions of differences in kappa receptors mediating the antinociceptive effects of these agonists. Quadazocine, however, also antagonized the antinociceptive effects of both DAMGO (opioid mu agonist) and DPDPE (opioid delta agonist) at doses approximately 3-fold less than those needed to attenuate significantly the effects of bremazocine. The structurally diverse kappa opioids (+-)-trans-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzo[b]- thiophene-4-acetamide (PD 117,302), ethylketocyclazocine (EKC) and tifluadom were studied under kappa-selective conditions, and the sensitivity of their effects to 1S,2S-trans-2-isothiocyanato-4,5-dichloro-N-[2(1- pyrrolidinyl)cyclohexyl]benzeneacetamide [(-)-UPHIT] (kappa 1 antagonist) or quadazocine (kappa 2 antagonist) was determined. On this basis PD 117,302, EKC and tifluadom were classified as acting at opioid kappa 1, kappa 1, and kappa 2 receptors, respectively; EKC and tifluadom were also shown to have significant activity at opioid mu, but not delta, receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesics↗
PubMed1993

Effects of neuropeptide Y, peptide YY and sigma ligands on ion transport in mouse jejunum.

The effects of putative sigma ligands and two neuropeptides on intestinal ion transport were evaluated in isolated sheets of whole mouse jejunum mounted in Ussing flux chambers. Serosal administration of neuropeptide Y (NPY), peptide YY (PYY), (+)-N-cyclopropylmethyl-N-methyl-1,4- diphenyl-1-ethyl-but-3-en-1-ylamine hydrochloride (JO 1784), di(ortho-tolyl)guanidine (DTG) and (+)- or (-)-N-allyl-normetazocine (NANM) produced concentration-related decreases in short-circuit current (Isc) without changes in tissue conductance. Although NPY and PYY were active in nanomolar concentrations, JO 1784, DTG and (+)- and (-)-NANM were active in micromolar concentrations; the rank order of potency in inhibiting Isc was PYY > NPY >> JO 1784 = (-)-N- cyclopropylmethyl-N-methyl-1,4-diphenyl-1-ethyl-but-3-en-1-ylamine hydrochloride > DTG > (+)-NANM = (-)-NANM. Serosal application of tetrodotoxin effectively blocked the decrease in Isc associated with all of the ligands tested. The activity of the serosally applied ligands was blocked by prior application of chlorisondamine, a ganglionic blocker. The effects of JO 1784 and NPY were evaluated using antagonists of several receptor types. Although application of serosal haloperidol had no effect alone up to concentrations of 1 microM, this compound produced a rightward displacement in both the NPY and JO 1784 concentration-effect curves. In contrast, sulpiride, SCH-23390, naloxone, yohimbine and prazosin failed to antagonize the effects of NPY or JO 1784.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Cocaine place preference is blocked by the delta-opioid receptor antagonist, naltrindole.

Naltrindole, a selective delta-opioid receptor antagonist, was evaluated for its potential to block the reinforcing properties of cocaine using a conditioned place pairing paradigm in Lewis rats. Cocaine HCl (15 mg/kg s.c.) produced a strong place preference which was significantly blocked in animals pretreated with naltrindole (3 mg/kg i.p.); naltrindole alone showed no reinforcing or aversive effects. The results suggest a novel approach for the treatment of cocaine abuse in man.

Animals↗
PubMed1992

Lack of antinociceptive efficacy of intracerebroventricular [D-Ala2,Glu4]deltorphin, but not [D-Pen2,D-Pen5]enkephalin, in the mu-opioid receptor deficient CXBK mouse.

The antinociceptive efficacy of [D-Pen2,D-Pen5]enkephalin (DPDPE) (delta 1 agonist) and [D-Ala2,Glu4]deltorphin (delta 2 agonist) was evaluated following intracerebroventricular (i.c.v.) or intrathecal (i.t.) administration in CD-1 and CXBK strains of mice using the radiant heat tail-flick test. Following i.c.v. administration, [D-Ala2,Glu4]deltorphin was effective in CD-1, but not CXBK, mice; DPDPE was approximately equiactive in both strains. While i.c.v. [D-Ala2,Glu4]deltorphin did not produce antinociception in the CXBK mouse, it effectively antagonized the antinociceptive actions of i.c.v. DPDPE. [D-Ala2,Glu4]deltorphin was effective following i.t. administration in both strains. These data suggest possible differences in the supraspinal populations of opioid delta receptor subtypes in the CXBK strain. On the basis of previously established selectivity of these agonists, the CXBK mouse may have a predominate population of supraspinal opioid delta 1, rather than delta 2, receptors.

Analgesics↗
PubMed1992

Treatment parameters of desensitization to capsaicin.

Desensitization of sensory afferents with topical capsaicin has been employed to treat a variety of neuropathic disorders in humans, however, few studies have been undertaken to systematically evaluate treatment parameters to determine the optimal dose and frequency of treatment needed to achieve and maintain desensitization. The effects of several treatment parameters, including dose, number of exposures, interval between exposures and duration of exposure, on the development, magnitude and duration of desensitization following local treatment with capsaicin and related compounds are described.

Animals↗
PubMed1992

Antinociceptive interactions of opioid delta receptor agonists with morphine in mice: supra- and sub-additivity.

In this study, the antinociceptive interactions of fixed ratio combinations of intracerebroventricularly (i.c.v.) given morphine and subantinociceptive doses of the delta agonists, [D-Pen2, D-Pen5]enkephalin (DPDPE), [D-Ala2, Glu4]deltorphin (DELT) or [Met5]enkephalin (MET) were examined using the mouse warm water tail flick test. When morphine was coadministered with DPDPE or DELT in a 4:1 and 9:1 mixture, respectively, a synergistic antinociceptive effect was observed. In contrast, when morphine was coadministered with MET in a 1:2 fixed ratio mixture, a subadditive interaction occurred. These results demonstrate both positive and negative modulatory interactions of delta agonists with morphine in an antinociceptive endpoint and that these interactions can be either supra- or subadditive. The data support the concept of a functional interaction between opioid mu and delta receptors and a potential regulatory role for the endogenous ligands of the opioid delta receptor.

Analgesics↗
PubMed1992

Characterization of [3H]naltrindole binding to delta opioid receptors in rat brain.

[3H]Naltrindole binding characteristics were determined using homogenized rat brain tissue. Saturation binding studies at 25 degrees C measured an equilibrium dissociation constant (Kd) value of 37.0 +/- 3.0 pM and a receptor density (Bmax) value of 63.4 +/- 2.0 fmol/mg protein. Association binding studies showed that equilibrium was reached within 90 min at a radioligand concentration of 30 pM. Naltrindole, as well as the ligands selective for delta (delta) opioid receptors, such as pCI-DPDPE and Deltorphin II inhibited [3H]naltrindole binding with nanomolar IC50 values. Ligands selective for mu (mu) and kappa (kappa) opioid receptors were only effective in inhibiting [3H]naltrindole binding at micromolar concentrations. From these data, we conclude that [3H]naltrindole is a high affinity, selective radioligand for delta opioid receptors.

Animals↗
PubMed1992

Spinal opioid delta antinociception in the mouse: mediation by a 5'-NTII-sensitive delta receptor subtype.

Previous studies from our laboratory have indicated that i.c.v. pretreatment of mice with the novel, selective opioid delta receptor antagonists, [D-Ala2,Leu5,Cys6]enkephalin (DALCE) and naltrindole-5'-isothiocyanate (5'-NTII), differentially antagonized the direct antinociceptive effects of [D-Pen2,D-Pen5]enkephalin (DPDPE) and [D-Ala2]deltorphin II (DELT). These findings, and others, suggested the existence of subtypes of opioid delta receptors which could be classified as activated by DPDPE and DALCE sensitive (delta 1 receptor), or selectively activated by DELT and 5'-NTII sensitive (delta 2 receptor). The present study has extended these observations to the characterization of delta-mediated antinociception effects of DPDPE and DELT after i.t. administration in mice using pretreatment with DALCE and 5'-NTII in order to selectively antagonize the delta subtypes. Additionally, the acute antinociceptive actions of DALCE itself were studied to ensure activity of this compound at the spinal level. The respective antinociceptive A50 value (95% CL) for i.t. DPDPE, DELT and DALCE were 19.0 (12.9-28.1), 19.3 (16.1-23.1) and 2.0 (1.4-3.0) nmol. The delta antagonist, N,N-diallyl-Try-Aib-Aib-Phe-Leu-OH (ICI 174,864) (where Aib is alpha-aminoisobutyric acid) blocked the antinociceptive effects of DPDPE and DELT, but not those of i.t. morphine or [D-Ala2,NMPhe4,Gly-ol5]enkephalin (DAMGO), indicating that the observed antinociceptive effects of DPDPE and DELT were delta mediated. Pretreatment 24 hr before testing with graded doses of i.t. 5'-NTII blocked the i.t. antinociceptive effects of DPDPE and DELT, although at least a 10-fold higher dose of 5'-NTII was needed to produce equivalent antagonism of DPDPE.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗
PubMed1992

Extremely long-lasting antagonistic actions of nor-binaltorphimine (nor-BNI) in the mouse tail-flick test.

The duration of antagonistic action of nor-binaltorphimine (nor-BNI), a kappa antagonist, of antinociception resulting from selective opioid agonists, was examined using the mouse tail-flick assay as the endpoint. Nor-BNI (1 nmol, i.c.v. at -20 min) antagonized equiantinociceptive doses of the opioid kappa agonists (5 alpha,7 alpha,8 beta)-(-)-N-methyl-N-(7-(1-pyrrolidinyl)-1-oxaspiro (4,5)dec-8-yl) benzeneacetamide (U69,593) (70 nmol i.c.v.) or bremazocine (25 nmol i.c.v.), but did not antagonize antinociception produced by the mu opioid-selective [D-Ala2, NMePhe4, Gly-ol]enkephalin or the delta opioid-selective [D-Pen2, D-Pen5]enkephalin. Pretreatment with nor-BNI (1 nmol i.c.v.) antagonized the antinociceptive effects of U69,593 and bremazocine for up to 28 days. At all pretreatment times, the antinociceptive dose-response lines for these kappa agonists were displaced to the right to various degrees in a parallel fashion; an increasing rightward displacement of the U69,593 and bremazocine antinociceptive dose-response lines was observed at 1 and 3 days after a single nor-BNI pretreatment, with a gradual return toward the control level at later times after pretreatment. Increasing the dose of nor-BNI to 10 nmol produced only a transient blockade of equiantinociceptive doses of the mu selective agonist [D-Ala2, NMePhe4, Gly-ol]enkephalin and the delta selective agonist [D-Pen2, D-Pen5]enkephalin (at 20-30 min post-nor-BNI pretreatment).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1992

Mediation of swim-stress antinociception by the opioid delta 2 receptor in the mouse.

The present study has characterized the antinociceptive response to cold water swim-stress (CWSS) in mice using opioid-selective antagonists as well as tolerance and cross-tolerance approaches. Mice subjected to CWSS using water at 5 degrees C for 3 min showed a marked antinociceptive response in the tail-flick test, which reached approximately 90% after +10 min, and which persisted for 15 to 20 min. This antinociceptive response (at +10 min) was antagonized by naloxone or by the delta antagonist ICI 174,864. Additionally, the CWSS response was antagonized by the opioid delta 2 antagonist, naltrindole-5'-isothiocyanate, but not by the delta 1 antagonist, [D-Ala2,Leu5,Cys6]enkephalin, or by the mu antagonist, beta-funaltrexamine or by the kappa antagonist, norbinaltorphimine. Although the CWSS-induced antinociceptive effect was blocked by some delta antagonists and tolerance resulted from the CWSS-induced response, the decrease in body temperature after each CWSS exposure was not affected by the opioid antagonists and reliably occurred in CWSS-tolerant mice, suggesting that the observed antinociception was independent of changes in body temperature. In mice rendered tolerant to the antinociceptive actions of the mu agonist, [D-Ala2,NMPhe4,Gly-ol] enkephalin, or to [D-Pen2,D-Pen5]enkephalin (predominantly a delta 1 agonist), the CWSS-induced antinociceptive response was unaltered. In contrast, in mice tolerant to the delta 2 agonist, [D-Ala2,Glu4]deltorphin, the CWSS-induced antinociceptive response was markedly and significantly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia↗
PubMed1992

Modulation of mu-mediated antinociception in the mouse involves opioid delta-2 receptors.

Recently, subtypes of the opioid delta receptor have been identified. It is not known, however, if a subtype of opioid delta receptor can be associated with the known modulatory action of delta agonists on mu-mediated antinociception. Thus, the present study has used the delta subtype-selective antagonists, [D-Ala2,Leu5,Cys6]enkephalin (DALCE) (delta 1 antagonist) and naltrindole-5'-isothiocyanate (5'-NTII) (delta 2 antagonist) in an effort to determine whether the positive and negative modulation of morphine antinociception produced by opioid delta agonists was the result of activity at specific subtypes of opioid delta receptors. Intracerebroventricular morphine produced a dose-related antinociceptive effect which was not antagonized by coadministration of the delta antagonist, ICI 174,864, or by pretreatment 24 hr before testing with the DALCE or 5'-NTII. Coadministration with morphine of a nonantinociceptive dose of DPDPE or [D-Ala2,Glu4]deltorphin resulted in a leftward displacement of the morphine dose-effect curve (i.e., positive modulation), whereas coadministration of a nonantinociceptive dose of [Met5]enkephalin with morphine resulted in a rightward displacement of the morphine dose-effect curve (i.e., negative modulation). Both the positive and the negative modulatory actions were antagonized when the experiment was conducted in the presence of the delta antagonist, ICI 174,864, or when the mice were pretreated with the delta 2 antagonist, 5'-NTII. In contrast, pretreatment with the delta 1 antagonist, DALCE, failed to affect either the positive or the negative modulatory actions of these delta agonists on morphine antinociception. The data suggest the involvement of an opioid delta 2 receptor in the modulation of morphine antinociception.

Animals↗
PubMed1992

Thermodynamic analysis of the temperature dependence of the dissociation constant of naloxone at opioid delta receptors in the mouse isolated vas deferens.

Dissociation constants (KB) for naloxone inhibition of the actions of DPDPE in the mouse isolated vas deferens preparation (inhibition of electrically induced twitch) were determined at five temperatures ranging between 25 and 40 degrees C. The values of KB tended to increase with temperature over the range examined, indicating that the affinity of naloxone for the opioid delta receptor is an inverse function of temperature. Using these data, the thermodynamic quantities delta G zero' (change in free energy), delta H zero' (change in enthalpy) and delta S zero' (change in entropy) were calculated from a van't Hoff plot of in (KB) against 1/T. The thermodynamic quantities determined in this study in vivo (delta G zero' = -10.59 kcal mol-1, delta H zero' = -15.73 kcal mol-1 and delta S zero' = -0.0168 kcal mol-1 zero K-1) are consistent with data reported from radioligand binding studies in vitro and suggest that the interaction between naloxone and the opioid delta receptor in the mouse isolated vas deferens is enthalpy driven. These data represent the first evaluation of the thermodynamics of opioid antagonist/receptor interaction in a physiological assay.

Animals↗
PubMed1992

Involvement of adenosine in antinociception produced by spinal or supraspinal receptor-selective opioid agonists: dissociation from gastrointestinal effects in mice.

Possible involvement of adenosine, as a secondary neurotransmitter, in opioid modulation of nociception and gastrointestinal function was investigated in mice. Inhibitory actions of theophylline, a nonselective adenosine receptor antagonist, were evaluated against effects evoked by opioid receptor-selective agonists administered at spinal or supraspinal sites. Intrathecal administration of theophylline significantly inhibited antinociceptive actions produced by intrathecal (i.th.) injections of morphine, [D-Ala2, NMPhe4, Gly-ol] enkephalin (DAMGO), [D-Pen2, D-Pen5] enkephalin (DPDPE) and beta-endorphin as measured with the warm water tail-flick assay. The rank order of rightward displacement of i.th. agonist dose-response curves by theophylline (i.th.) was DPDPE (greatest) > DAMGO > morphine > beta-endorphin. Theophylline was less effective as an inhibitor in the hot-plate assay. Additionally, i.th. administration of theophylline inhibited antinociceptive effects evoked by i.c.v. administration of opioids. The rank order of rightward displacement of dose-response curves after i.c.v. opioid administration was DAMGO (greatest) > beta-endorphin > morphine > DPDPE. In contrast to the effectiveness of theophylline administered i.th., theophylline coadministered i.c.v. with opioid agonists did not inhibit opioid-induced antinociception. Neither i.th. nor i.c.v. theophylline altered inhibitory effects on gastric emptying and gastrointestinal propulsion produced by i.th. or i.c.v. administration of selective opioid agonists. These data provide additional support for involvement of spinal adenosine as a secondary neurotransmitter in opioid antinociceptive processes associated with local spinal reflexes as well as in descending antinociceptive processes. Adenosine was not involved in modulation of opioid-activated gastrointestinal outflow pathways at either spinal or supraspinal levels.

Adenosine↗
PubMed1992

Whole body and brain distribution of [3H]cyclic [D-Pen2,D-Pen5] enkephalin after intraperitoneal, intravenous, oral and subcutaneous administration.

The route of administration of a given drug can have a significant influence upon whole body distribution. The present study examined whole body distribution of the delta opioid receptor-selective peptide [3H]DPDPE in male CD1 mice after administration by several routes. Additionally, we describe regional brain distribution of [3H]DPDPE after i.v. administration with and without pretreatment with naloxone or the selective delta receptor antagonist naltrindole. Finally, characterization of the inherent enzymatic stability of DPDPE was also examined. Intravenous administration results in a significantly large amount of [3H]DPDPE in the small intestine and flush at 15 and 30 min postadministration, suggesting rapid biliary excretion. The highest level in the brain after i.v. administration occurred at 60 min (0.08%). After i.p. and s.c. administration, large amounts of [3H]DPDPE were found in the small intestine and flush, but not until 60 min postadministration, suggesting a slower rate of absorption from the site of administration. The i.p. and s.c. groups' brain levels peaked at 120 min (0.07 and 0.09%, respectively). The highest levels in the brain after p.o. administration were seen at 240 min (0.03%). Examination of regional brain distribution data showed no significant difference in the levels of [3H]DPDPE between brain regions at any time point studied. However, naloxone pretreatment resulted in significant reductions of [3H]DPDPE in all brain regions at 5 and 10 min. Naltrindole pretreatment resulted in significant reductions in the frontal cortex and striatum at 5 and/or 10 min postadministration, but had no effect on [3H]DPDPE levels in cerebellum, hippocampus or brain stem.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Pharmacological characterization of [D-Ala2,Leu5,Ser6]enkephalin (DALES): antinociceptive actions at the delta non-complexed-opioid receptor.

Substantial evidence has been accumulated which suggests that opioid delta receptors may be distinguished on the basis of their involvement in the modulation (i.e., increase or decrease in potency) of mu-mediated antinociception. On this basis, it has been hypothesized that some opioid delta receptors exist within a functional complex with mu receptors (delta complexed (delta cx) receptors) while other delta sites do not (delta non-complexed (delta ncx) receptors). Recent work with [D-Ala2,Leu5,Cys6]enkephalin (DALCE) has demonstrated that this compound produces initial antinociceptive actions, does not modulate morphine antinociception and appears to bind irreversibly to the delta ncx site, presumably by means of thiol-disulfide exchange between the receptor and the cysteine sulfhydryl group. To determine if a structural basis exists for actions at the hypothesized delta ncx receptor, in the present study we report the synthesis and pharmacological characterization of [D-Ala2,Leu5,Ser6] enkephalin (DALES), a close structural analogue of DALCE. If a structural basis for action at the delta ncx site exists, then DALES would be predicted to produce antinociception, fail to modulate morphine antinociception and, since it lacks the free sulfhydryl group present in DALCE, fail to exhibit irreversible antagonistic actions; these predictions were supported. Additionally, pretreatment with DALCE at -24 h, but not with DALES, blocked DALES-induced antinociception. These observations in vivo support the concept of a structural basis for activity at the hypothesized delta ncx site and suggest that DALES, like DALCE, may be a useful probe for pharmacological characterization of putative delta receptor subtypes.

Analgesics↗
PubMed1991

Interaction of beta-funaltrexamine with [3H]cycloFOXY binding in rat brain: further evidence that beta-FNA alkylates the opioid receptor complex.

beta-Funaltrexamine (beta-FNA) is an alkylating derivative of naltrexone. In addition to acting as an irreversible inhibitor of mu-receptor-mediated physiological effects, intracerebroventricular (i.c.v.) administration of beta-FNA to rat attenuates the ability of selective delta receptor antagonists and naloxone to reverse delta receptor-mediated effects. Moreover, recent work demonstrated that i.c.v. administration of beta-FNA alters the conformation of the opioid receptor complex, as inferred by a decrease in the Bmax of the lower affinity [3H][D-ala2,D-leu5]enkephalin binding site. Consistent with the decreased potency of naloxone as an inhibitor of delta receptor mediated effects, beta-FNA doubled the naloxone IC50 for displacing [3H][D-ala2,D-leu5]enkephalin from its lower affinity binding site. These data collectively support the hypothesis that the opioid receptor complex postulated to mediate mu-delta interactions in vivo is identical to the opioid receptor complex as defined by vitro ligand binding studies. A direct prediction of this hypothesis is that beta-FNA should increase the Kd of antagonists for the mu binding site (mu cx) of the receptor complex. The data reported in this paper demonstrate that beta-FNA doubled the IC50 of the potent narcotic antagonist, 6-desoxy-6 beta-fluoronaltrexone (cycloFOXY) for displacing [3H][D-ala2,D-leu5]enkephalin from its lower affinity binding site, and doubled the Kd of [3H]cycloFOXY for its mu binding site, providing additional data that the mu binding site labeled by [3H]cycloFOXY is the mu binding site of the opioid receptor complex. beta-FNA also altered the kappa binding site labeled by [3H]cycloFOXY, and when administered intrathecally to mice, beta-FNA produced a longlasting antinociception in the acetic acid writhing test.

Alkylating Agents↗
PubMed1991

Development of delta opioid peptides as nonaddicting analgesics.

Although much effort has been devoted to opioid research since the identification of enkephalins, understanding of the physiological importance and mechanisms of action of endogenous opioids lags behind understanding of opiate alkaloids such as morphine. In recent years, several novel approaches have been refined with promise for the successful development of the long-awaited nonaddicting analgesics that act at the opioid delta receptor. The present communication reviews these efforts.

Analgesics↗