Mechanism of kyotorphin-induced release of Met-enkephalin from guinea pig striatum and spinal cord

doi:10.1016/0006-8993(81)91070-2

Brain Research

Volume 221, Issue 1, 21 September 1981, Pages 161-169

https://doi.org/10.1016/0006-8993(81)91070-2 Get rights and content

Abstract

The characteristics of kyotorphin (Tyr-Arg)-induced release of Met-enkephalin from the striatum and the spinal cord of guinea pig were determined by superfusing the slices in vitro and then carrying out radioimmunoassays. Depolarization by 50 mM K⁺ induced a marked release of Met-enkephalin-like immunoreactivity. The potassium-induced release of Met-enkephalin was calcium-dependent. In preparations from the striatum, the addition of kyotorphin to the superfusion medium produced a concentration-dependent increase in Met-enkephalin. The kyotorphin-induced release of Met-enkephalin was calcium-dependent and was abolished by tetrodotoxin. Similar effects of kyotorphin were seen in the spinal cord preparations. Electrical field stimulation of the striatal slices at a frequency of 10 Hz also evoked significant and calcium-dependent increases in the release of Met-enkephalin and markedly enhanced the kyotorphin-induced release of Met-enkephalin, as compared to the controls not given field stimulation. These results suggest that kyotorphin depolarizes the so-called enkephalinergic neurons and releases Met-enkephalin from the nerve terminals. This effect of kyotorphin may be a possible mechanism related to the manifestation of analgesia.

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Regional distribution of a novel analgesic dipeptide kyotorphin (Tyr-Arg) in the rat brain and spinal cord
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Cited by (62)

Blockade of analgesic effects following systemic administration of N-methyl-kyotorphin, NMYR and arginine in mice deficient of preproenkephalin or proopiomelanocortin gene
2018, Peptides
Citation Excerpt :
Kyotorphin is an analgesic dipeptide (l-tyrosine-l-arginine), which was isolated from bovine brain by use of in vivo analgesic assay system [1]. As kyotorphin causes an in vitro release of Met-enkephalin from the striatal slices [1,2], but shows neither binding activity to opioid receptors nor inhibiting activity of enkephalin degrading enzymes [1,3,4], this dipeptide is known as an enkephalin releaser. Although details remain elusive, there are several studies showing that opioid receptor antagonist, naloxone blocked various pharmacological or physiological actions of kyotorphin [5,6,3,7].
Kyotorphin is a unique biologically active neuropeptide (l-tyrosine-l-arginine), which is reported to have opioid-like analgesic actions through a release of Met-enkephalin from the brain slices. N-methyl-l-tyrosine-l-arginine (NMYR), an enzymatically stable mimetic of kyotorphin, successfully caused potent analgesic effects in thermal and mechanical nociception tests in mice when it was given through systemic routes. NMYR analgesia was abolished in μ-opioid receptor-deficient (MOP-KO) mice, and by intracerebroventricular (i.c.v.) injection of naloxone and of N-methyl l-leucine-l-arginine (NMLR), a kyotorphin receptor antagonist. In the Ca²⁺-mobilization assay using CHO cells expressing Gα_qi5 and hMOPr or hDOPr, however, the addition of kyotorphin neither activated MOPr-mechanisms, nor affected the concentration-dependent activation of DAMGO- or Met-Enkephalin-induced MOPr activation, and Met-enkephalin-induced DOPr activation. NMYR-analgesia was significantly attenuated in preproenkephalin (PENK)- or proopioimelanocortin (POMC)-KO mice. The systemic administration of arginine, which is reported to elevate the level of endogenous kyotorphin selectively in midbrain and medulla oblongata, pain-related brain regions, caused significant analgesia, and the analgesia was reversed by i.c.v. injection of NMLR or naloxone. In addition, PENK- and POMC-KO mice also attenuated the arginine-induced analgesia. All these findings suggest that NMYR and arginine activate brain kyotorphin receptor in direct and indirect manner, respectively and both compounds indirectly cause the opioid-like analgesia through the action of endogenous opioid peptides.
The orexigenic effect of kyotorphin in chicks involves hypothalamus and brainstem activity and opioid receptors
2013, Neuropeptides
Citation Excerpt :
Kyotorphin (KTP) is a central dipeptide (l-tyrosyl–l-arginine) first isolated in the bovine brain (Takagi et al., 1979) and since found in other vertebrates including mice, rats, guinea pigs, rabbits (Shiomi et al., 1981; Ueda et al., 1980) and humans (Nishimura et al., 1991).
Kyotorphin (KTP), first isolated in the bovine brain and now having been identified in a variety of species, is known most extensively for its analgesic-like properties. KTP indirectly stimulates opioid receptors by releasing methionine enkephalin (met-enkephalin). Stimulation of opioid receptors is linked to hunger perception. In the present study, we sought to elucidate the effect of KTP on food intake in the neonatal chick. Intracerebroventricular injection of 0.6, 3.0 and 12 nmol KTP increased feeding up to 60 min post-injection. KTP treated chicks increased pecking efficiency and decreased time spent in deep rest, 20 and 30 min following injection, respectively. Gastrointestinal transit rate was not affected by KTP. Blocking mu, delta, and kappa opioid receptors suppressed orexigenic effects of KTP, suggesting that all three types are involved in KTP’s stimulatory effect. The lateral hypothalamus (LH) and arcuate nucleus (ARC) of the hypothalamus and the nucleus of the solitary tract (NTS), within the brainstem had increased numbers of c-Fos immunoreactive cells following KTP treatment. In conclusion, KTP caused increased feeding in broiler-type chicks, likely through activation of the LH, ARC, and NTS.
Stimulation of Na+/Cl-coupled opioid peptide transport system in SK-N-SH cells by L-kyotorphin, an endogenous substrate for H+-coupled peptide transporter PEPT2
2008, Drug Metabolism and Pharmacokinetics
We have recently identified a Na⁺/Cl⁻-coupled transport system in mammalian cells for endogenous and synthetic opioid peptides. This transport system does not transport dipeptides/tripeptides, but is stimulated by these small peptides. Here we investigated the influence of L-kyotorphin (L-Tyr-L-Arg), an endogenous dipeptide with opioid activity, on this transport system. The activity of the transport system, measured in SK-N-SH cells (a human neuronal cell line) with deltorphin II as a model substrate, was stimulated ~ 2.5-fold by L-kyotorphin, with half-maximal stimulation occurring at ~ 100 μM. The stimulation was associated primarily with an increase in the affinity for deltorphin II. The stimulation caused by L-kyotorphin was stereospecific; L-Tyr-D-Arg (D-kyotorphin) had minimal effect. The influence of L-kyotorphin was observed also in a different cell line which expressed the opioid peptide transport system. While L-kyotorphin is a stimulator of opioid peptide transport, it is a transportable substrate for the H⁺-coupled peptide transporter PEPT2, which is expressed widely in the brain. Since the activity of the opioid peptide transport system is modulated by extracellular L-kyotorphin and since PEPT2 is an important determinant of extracellular L-kyotorphin in the brain, the expression/activity of PEPT2 may be a critical factor in the modulation of opioidergic neurotransmission in vivo.
The pH-dependent conformational states of kyotorphin: A constant-pH molecular dynamics study
2007, Biophysical Journal
Citation Excerpt :
These results led to the suggestion that the dipeptide binds to a specific receptor (KTP receptor, KTPr) (56), triggering a cascade of events that leads to strong analgesia in the brain (57,63). Two mechanisms of action have been proposed: 1), direct activation of the KTPr, inducing Met-enkephalin release (which can activate the δ-receptor), followed by Gαi and phospholipase C activations (64,65); 2), a fast degradation of KTP, resulting in L-Arg, which is a potent substrate for nitric oxide synthase, with the NO thus formed inducing the release of Met-enkephalin (66). Despite the fact that several studies (45,53,54) confirm the existence of a KTPr, it has not yet been identified.
An extensive conformational study of the analgesic dipeptide kyotorphin (L-Tyr-L-Arg) at different pH values was performed using a constant-pH molecular dynamics method. This dipeptide showed a remarkable pH-dependent conformational variety. The protonation of the N-terminal amine was identified as a key element in the transition between the more extended and the more packed conformational states, as monitored by the dihedral angle defined by the atoms 1Cβ-1Cα-2Cα-2Cβ. The principal-component analysis of kyotorphin identified two major conformational populations (the extended trans and the packed cis) together with conformations that occur exclusively at extreme pH values. Other, less stable conformations were also identified, which help us to understand the transitions between the predominant populations. The fitting of kyotorphin's conformational space to the structure of morphine resulted in a set of conformers that were able to fulfill most of the constraints for the μ-receptor. These results suggest that there may be strong similarities between the kyotorphin receptor and the structural family of opioid receptors.
Interaction of endogenous ligands mediating antinociception
2006, Brain Research Reviews
It is well known that a multitude of transmitters and receptors are involved in the nociceptive system, some of them increasing and others inhibiting the pain sensation both peripherally and centrally. These substances, which include neurotransmitters, hormones, etc., can modify the activity of nerves involved in the pain pathways. Furthermore, the organism itself can express very effective antinociception under different circumstances (e.g. stress), and, during such situations, the levels of various endogenous ligands change. A very exciting field of pain research relates to the roles of endogenous ligands. Most of them have been suggested to influence pain transmission, but only a few studies have been performed on the interactions of different endogenous ligands. This review focuses on the results of antinociceptive interactions after the co-administration of endogenous ligands. The data based on 55 situations reveal that the interactions between the endogenous ligands are very different, depending on the substances, the pain tests, the species of animals and the route of administrations. It is also revealed that only a few of the possible interactions between endogenous ligands have been investigated to date, in spite of the fact that the type of antinociceptive interaction between different endogenous ligands could hardly be predicted. The results indicate that the combination of endogenous ligands should not be omitted from the pain therapy arsenal. Attention will hopefully be drawn to the complex interdependence of endogenous ligands and their potential use in clinical practice.
Dynorphin-mediated antinociceptive effects of l-arginine and SIN-1 (an NO donor) in mice
2006, Brain Research Bulletin
The antinociceptive response of mice to the amino acid l-arginine (l-ARG) has been attributed to either an opioid mechanism or a non-opioid but nitric oxide (NO)-dependent mechanism. Earlier it was reported that the mechanism of nitrous oxide-induced antinociception involved opioid components and was also dependent on brain NO. This study was designed to determine whether the antinociceptive effects of l-ARG and the NO donor 3-morpholinosydnoimine (SIN-1) might be mediated by brain mechanisms similar to those that are responsible for nitrous oxide (N₂O) antinociception. l-ARG and SIN-1 were administered to mice intracerebroventricularly (i.c.v.), and antinociception was assessed using the acetic acid abdominal constriction test. Both l-ARG and SIN-1 caused dose-related antinociceptive effects that were blocked by naloxone and norbinaltorphimine. The antinociceptive effects of both SIN-1 and l-ARG were also blocked to a greater extent by i.c.v. administration of a rabbit antiserum against rat dynorphin 1–13 than an antiserum against methionine-enkephalin, suggesting that the SIN-1 and l-ARG effects may be related to stimulated release of dynorphin. The antinociceptive effect of l-ARG was antagonized by an inhibitor of neuoronal NO synthase enzyme, indicating that l-ARG had to be converted to NO for its antinociceptive action. These findings indicate that the mechanisms of antinociceptive action of l-ARG and SIN-1 are both mediated by dynorphin and dependent on NO.

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Abstract

References (15)

Analgesia induced by microinjection of morphine into, and electrical stimulation of, the nucleus reticularis paragigantocellularis of rat medulla oblongata

Neuropharmacology

Potassium-induced release of enkephalins from rat striatal slices

Europ. J. Pharmacol.

K-stimulated release of Leu- and Met-enkephalin from rat striatal slices: lack of effect of morphine and naloxone

Europ. J. Pharmacol.

Effects of tyrosyl-arginine (kyotorphin), a new opioid dipeptide, on single neurons in the spinal dorsal horn of rabbits and the nucleus reticularis paragigantocellularis of rats

Neurosci. Lett.

Morphine-like analgesia by a new dipeptide, l-tyrosyl-l-arginine (Kyotorphin) and its analogue

Europ. J. Pharmacol.

Comparison of the analgesic effects of various opioid peptides by a newly devised intracisternal injection technique in conscious mice

Europ. J. Pharmacol.

Regional distribution of a novel analgesic dipeptide kyotorphin (Tyr-Arg) in the rat brain and spinal cord

Brain Research

Cited by (62)

Blockade of analgesic effects following systemic administration of N-methyl-kyotorphin, NMYR and arginine in mice deficient of preproenkephalin or proopiomelanocortin gene

The orexigenic effect of kyotorphin in chicks involves hypothalamus and brainstem activity and opioid receptors

Stimulation of Na<sup>+</sup>/Cl<sup>-</sup>coupled opioid peptide transport system in SK-N-SH cells by L-kyotorphin, an endogenous substrate for H<sup>+</sup>-coupled peptide transporter PEPT2

The pH-dependent conformational states of kyotorphin: A constant-pH molecular dynamics study

Interaction of endogenous ligands mediating antinociception

Dynorphin-mediated antinociceptive effects of l-arginine and SIN-1 (an NO donor) in mice

Research reportMechanism of kyotorphin-induced release of Met-enkephalin from guinea pig striatum and spinal cord

Abstract

Neuropharmacology

Europ. J. Pharmacol.

Europ. J. Pharmacol.

Neurosci. Lett.

Europ. J. Pharmacol.

Europ. J. Pharmacol.

Brain Research

Research report
Mechanism of kyotorphin-induced release of Met-enkephalin from guinea pig striatum and spinal cord