Endogenous opiates: 1989

Olson, Gayle A.; Olson, Richard D.; Kastin, Abba J.

doi:10.1016/0196-9781(90)90163-y

Cited by 54 publications

(13 citation statements)

References 322 publications

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“…In general, the opioid agonists tend to interfere with learning and the antagonists tend to facilitate them, although there are many exceptions to this rule (Izquierdo, 1980;Izquierdo and Graudenz, 1980;Olson et al, 1990).…”

Section: Discussionmentioning

confidence: 92%

Naloxone Ameliorates the Learning Deficit Induced by Pentylenetetrazol Kindling in Rats

Becker

Grecksch

Brosz

1994

Eur J of Neuroscience

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Endogenous opioid peptides modulate and regulate processes of central excitability. Furthermore, opioids are thought to interfere with processes of learning and memory storage. In order to study the effects of endogenous opioids on both processes we injected in the course of development of pentylenetetrazol kindling the opiate receptor antagonist naloxone, and tested the animals afterwards in a shuttle-box task. It was found that naloxone pretreatment had dissociative effects. There was no effect on seizure outcome, whereas the learning deficit was ameliorated in the kindled group. The data suggest that endogenous opioid peptides contribute to the learning deficit found in pentylenetetrazol-kindled rats.

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Section: Discussionmentioning

confidence: 92%

Naloxone Ameliorates the Learning Deficit Induced by Pentylenetetrazol Kindling in Rats

Becker

Grecksch

Brosz

1994

Eur J of Neuroscience

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“…In addition, the learning performance of control animals pretreated with naltrindole was very low. Although many exceptions can be found, the general action of µ-and δ-opioid receptor agonists is to impair learning and memory and of the antagonists is to facilitate them and to alleviate amnesia (Olson et al 1990(Olson et al , 1995Izquierdo 1980;McGaugh 1990;Ilyutchenok and Dubrovina 1995). Specifically, δ-opioid receptor agonists have been demonstrated to produce amnesia (Schulteis et al 1988;Pakarinen et al 1995;Ukai et al 1997) and selective δ-opioid antagonist reversed an induced learning impairment (Schulteis and Martinez 1990) and enhanced memory retrieval (Ilyutchenok and Dubrovina 1995).…”

Section: Discussionmentioning

confidence: 93%

Involvement of δ-opioid receptors in pentylenetetrazol kindling development and kindling-related processes in rats

Grecksch

Becker

Schroeder

et al. 1999

Naunyn-Schmiedeberg's Arch Pharmacol

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The role of delta-opioid receptors on the development of kindling induced by the convulsant pentylenetetrazol (37.5 mg kg(-1) i.p.) was investigated in rats. Besides the seizure development, the kindling induced enhancement of glutamate binding and the kindling-induced learning deficit were examined. A clear depression of kindling development by blocking of delta-opioid receptors by intracerebroventricular administration of naltrindole (10 nmol/5 microl) was found. In an acute convulsion test performed 8 days after kindling completion, animals pretreated with naltrindole during kindling induction showed lower seizure stages compared to saline-pretreated kindled animals. The kindling-induced increase in hippocampal glutamate binding was completely prevented by naltrindole, whereas the kindling-induced learning deficit was not influenced. The learning performance of control animals pretreated with naltrindole was very low. It was hypothesized that the various consequences of kindling induction could be influenced separately. Summarizing the results, an involvement of the delta-opioid system in mechanisms underlying chemical kindling was clearly demonstrated. Interactions of endogenous opioid systems with glutamatergic transmission were suggested.

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“…The heterogeneity of opioid receptors and the existence of at least three main opioid receptor types, designated µ, δ and κ, is widely accepted [7]. In recent years a lot of evidence has been accumulated that indicates that the µ, δ and κ receptor types differ in their structural and conformational requirements for peptide ligand binding [8][9][10] and mediate different pharmacological and physiological effects ranging from inducing pain relief to preventing diarrhea [11]. The In this review we summarize the development of different types of conformationally constrained opioid peptide analogs that have led to highly potent and selective agonists and antagonists at all three opioid receptor types.…”

Section: Introductionmentioning

confidence: 99%

Conformationally Restricted Peptides as Tools in Opioid Receptor Studies

Janecka¹,

Kruszyński

2005

CMC

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The discovery of endogenous opioid peptides with their limited receptor selectivity more than two decades ago implicated their involvement in analgesia and initiated efforts to understand the molecular mechanisms underlying their action. Opioid peptides mediate their physiological and pharmacological effects through three major opioid receptor types (mu, delta, kappa), but the role of each of these receptors is not easy to distinguish. There has therefore, been an increasing need for potent and selective agonists and antagonists in this area. The incorporation of conformational constraints into analogs of biologically active peptides is a well-known approach for enhancing receptor selectivity and modulating efficacy. Conformational restriction has proven a valuable means for assessing disparities between the peptide binding characteristics at each of the opioid receptor types, since peptide analogs designed with appropriate conformational constraints possess the ability to adopt the conformation required for interaction at one receptor type but not another. In efforts to obtain better conformational integrity various conformationally restricted analogs of endogenous opioid peptides have been developed. In this paper we review the development of opioid analogs whose conformation was restricted either globally through different types of cyclization (such as amide bond formation, disulfide and monosulfide bridges, carbonyl and amine bridges) or locally, through incorporation of side-chain conformational constraints at a specific amino acid residue by synthesizing cyclic amino acids or constraining torsion angles by suitable substitutions. These two approaches have led to the development of potent and very selective agonists and antagonists at all three opioid receptor types.

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Endogenous opiates: 1989

Cited by 54 publications

References 322 publications

Naloxone Ameliorates the Learning Deficit Induced by Pentylenetetrazol Kindling in Rats

Naloxone Ameliorates the Learning Deficit Induced by Pentylenetetrazol Kindling in Rats

Involvement of δ-opioid receptors in pentylenetetrazol kindling development and kindling-related processes in rats

Conformationally Restricted Peptides as Tools in Opioid Receptor Studies

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