Isolation of a novel tetrapeptide with opiate and antiopiate activity from human brain cortex: Tyr-Pro-Trp-Gly-NH2 (Tyr-W-MIF-1)

Expression of the FOS proto-oncogene protein in brain after ICV administration of Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2)

Tyr-W-MIF-1 is a tetrapeptide recently isolated from brain that has opiate modulating activity. In this study, we used immunocytochemical (ICC) detection of FOS proto-oncogene protein to map brain areas activated by an ICV injection of Tyr-W-MIF-1 (200 micrograms). The analgesic effect of the peptide, which lasted 1 h, was confirmed in each rat with the tail flick test. FOS was activated in several limbic structures, including the cingulate and infralimbic cortex, nucleus accumbens, and central nucleus of the amygdala. FOS activation also occurred in several diencephalic nuclei, including the supraoptic, paraventricular, and periventricular nuclei of the hypothalamus, and the paraventricular nucleus of the thalamus. Several activated areas contained mu-opiate receptors. However, despite the known selectivity of Tyr-W-MIF-1 for mu receptors, FOS immunoreactivity was also induced in nuclei of the amygdala, hypothalamus, and thalamus, where concentrations of kappa receptors were high but those of mu and delta receptors were not detected. The results show that Tyr-W-MIF-1 induces FOS activation in several brain areas, including but not limited to, areas associated with nociception and stress-induced analgesia.

Cyclic analogues of Tyr-W-MIF-1 with prolonged analgesic activity and potency comparable to DAMGO and morphine

Two cyclic analogues of the brain peptide Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2) were synthesized and tested for analgesic activity in the rat tail flick test after intracerebroventricular (ICV) injection. The analogues were about 200-fold more potent than the parent peptide. Analgesia was dose dependent, and at 1 microgram the two analogues, the mu-selective enkephalin analogue DAMGO (Tyr-D-Ala-Gly-N-Me-Phe-Gly-ol), and morphine, all produced analgesia lasting between 40 and 60 min. Analgesia of longer duration was evident at higher doses of the analogues and lasted more than 6 h after 100 micrograms, the highest dose tested. The results show that peptide analogues based on the structure of the endogenously occurring Tyr-W-MIF-1 can produce potent and long-lasting effects on nociception.

CNS effects of peptides: a cross-listing of peptides and their central actions published in the journal Peptides, 1986-1993

The centrally mediated effects of peptides as published in the journal Peptides from 1986 to 1993 are tabulated in two ways. In one table, the peptides are listed alphabetically. In another table, the effects are arranged alphabetically. Most of the effects observed after administration of peptides are grouped, wherever possible, into categories such as cardiovascular and gastrointestinal. The species used in most cases has been rats; where other animals were used, the species is noted. The route of administration of peptides and source of information also are included in the tables, with a complete listing provided at the end. Many peptides have been shown to exert a large number of centrally mediated effects.

Isolation of a novel peptide with a unique binding profile from human brain cortex: Tyr-K-MIF-1 (Tyr-Pro-Lys-Gly-NH2)

Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2), Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2), and MIF-1 (Pro-Leu-Gly-NH2) are biologically active peptides previously isolated from brain tissue. We now have used size exclusion chromatography and several consecutive rp-HPLC steps monitored by RIA to isolate a structurally related peptide from human brain cortex with the sequence Tyr-Pro-Lys-Gly-NH2 (Tyr-K-MIF-1). Determination of the sequence, electrospray mass spectrometry, and comparison of its chromatographic behavior with synthetic Tyr-K-MIF-1 confirmed the structure. Unlike Tyr-MIF-1 and Tyr-W-MIF-1, Tyr-K-MIF-1 does not bind to the mu opiate site; unlike MIF-1, Tyr-K-MIF-1 can bind to the Tyr-MIF-1 site. Of these peptides, only Tyr-K-MIF-1 binds to its own site in brain tissue prepared in Tris buffer. Thus, a new member of the Tyr-MIF-1 family of peptides, with a unique profile of binding, has been isolated from human brain cortex.

Mu, delta, and kappa opiate receptor binding of Tyr-MIF-1 and of Tyr-W-MIF-1, its active fragments, and two potent analogs

The relative binding to mu, delta, and kappa opiate receptors was characterized for the brain peptides Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2), Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2), and two fragments of Tyr-W-MIF-1 (Tyr-Pro-Trp and Tyr-Pro-Trp-Gly) previously shown to have antagonist as well as agonist activity in the guinea pig ileum. Tyr-MIF-1 had relatively low affinity (Ki = 1 microM at the mu site) but high selectivity (400- and 700-fold greater affinity for mu over delta and mu over kappa binding). Tyr-W-MIF-1 (Ki = 71 nM at the mu site) showed higher affinity binding to all three sites than Tyr-MIF-1 while retaining 200-fold selectivity for mu over delta and kappa receptors. The affinity of the fragments of Tyr-W-MIF-1 was lower for mu but higher for delta receptors. We also tested two cyclized analogs of Tyr-W-MIF-1 that were about 200-fold more active than the parent compound in producing analgesia. These analogs showed higher affinity binding to all three opiate receptors. One of the analogs showed binding affinity to mu sites (Ki = 1.3 nM) that was within 3-fold of that of the potent analog of enkephalin, DAMGO. Thus, brain peptides with an N-terminal Tyr-Pro, rather than the Tyr-Gly-Gly-Phe sequence typical of other endogenous opiates, can provide high selectivity for mu opiate receptors. Analogs based on one of them, Tyr-Pro-Trp-Gly-NH2, show high affinity as well as potent analgesic activity.

Endogenous opiates: 1992

This paper is the fifteenth installment of our annual review of research concerning the opiate system. It includes papers published during 1992 involving the behavioral, non-analgesic, effects of the endogenous opiate peptides. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal and renal function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.

Endogenous peptide Tyr-Pro-Trp-Gly-NH2 (Tyr-W-MIF-1) is transported from the brain to the blood by peptide transport system-1

Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2) is a recently isolated peptide that belongs to a larger family that includes Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) and MIF-1 (Pro-Leu-Gly-NH2). Despite similarities in structure, Tyr-MIF-1 and MIF-1 can act differently in behavioral, blood-brain barrier (BBB) transport, and receptor binding systems. Tyr-W-MIF-1, like Tyr-MIF-1, has both opiate and antiopiate activity, but may be more opiate-like than Tyr-MIF-1. Tyr-MIF-1, but not MIF-1, is transported from brain to blood by peptide transport system (PTS)-1. PTS-1 transports mainly Tyr-MIF-1 and methionine enkephalin, but does not transport amino acids, peptide fragments of Tyr-MIF-1, D-Tyr-MIF-1, or unrelated peptides and proteins. We tested whether Tyr-W-MIF-1 also was transported across the BBB and, if so, whether PTS-1 was involved. 125I-Tyr-W-MIF-1 had a half-time disappearance from the brain of 22.4 min. This is faster than the efflux occurring with non-saturable reabsorption of the cerebrospinal fluid and, therefore, is consistent with saturable transport, but it is slower than the efflux rate of Tyr-MIF-1, suggesting a less robust transport than for Tyr-MIF-1 Self-inhibition with excess unlabeled Tyr-W-MIF-1 confirmed a saturable component, with a dose of 4.2 nmol producing 50% inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolonged analgesia after intracerebroventricular Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2)

A peptide recently isolated from human and bovine brain, Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2), was tested for its effects on nociception in the tail-flick test after intracerebroventricular injection in the rat. Tail-flick latencies were significantly increased with a rapid onset and remained significantly elevated for at least 50 min. Naloxone reversed the effect of the peptide, indicating opiate receptor involvement in the response. Met-enkephalin at the same dose produced only slight antinociception. Some animals showed 'barrel-rolling' behavior in addition to the analgesia; this behavior was unusually short-lived, not a prerequisite for the analgesia, and had no apparent persistent effects. The results show that, in addition to previously described opiate-like actions (binding to the mu-receptor and inhibition of electrically induced contractions of the guinea pig ileum), Tyr-W-MIF-1 is capable of inducing significant analgesia.

Isolation of Tyr-W-MIF-1 from bovine hypothalami

Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2) was recently isolated from human brain cortex. We have now isolated it from bovine hypothalami by solid phase extraction and several consecutive rpHPLC steps monitored by an RIA originally developed for the endogenous brain peptide Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2). Determination of the sequence of the purified material and comparison of its chromatographic behavior with synthetic Tyr-W-MIF-1 confirmed the structure. The synthetic peptide and the isolated material showed almost identical binding to mu opiate receptors.