"Near Cure" treatment of severe acute EAE in MIF-1-deficient female and male mice with a bifunctional MHCII-derived molecular construct

Our previous studies demonstrated increased serum levels of macrophage migration inhibitory factor (MIF-1) and its homologue, MIF-2, in males during MS progression; and that genetically high-MIF-expressing male subjects with relapsing multiple sclerosis (MS) had a significantly greater risk of conversion to progressive MS than lower-MIF-expressing males and females. However, female MS subjects with severe disease expressed higher levels of CD74, the common MIF-1/MIF-2 receptor, on blood cells. In the murine model of MS, experimental autoimmune encephalomyelitis (EAE), both male and female mice lacking MIF-1 and/or MIF-2 were clinically improved during development of moderately severe disease, thus implicating both homologs as co-pathogenic contributors. The current study using MIF-deficient mice with severe acute EAE revealed a highly significant reduction of EAE scores in MIF-1-deficient females, in contrast to only minor and delayed reduction of clinical signs in MIF-1-deficient males. However, clinical EAE scores and factor expression were strongly suppressed in males and further reduced in females after treatment of WT and MIF-1-, MIF-2- and MIF-1/2-DUAL-deficient female and male mice with a MHCII DRα1-MOG-35-55 molecular construct that competitively inhibits MIF-1 & MIF-2 signaling through CD74 as well as T cell activation. These results suggest sex-dependent differences in which the absence of the MIF-1 and/or MIF-2 genotypes may permit stronger compensatory CD74-dependent EAE-inducing responses in males than in females. However, EAE severity in both sexes could still be reduced nearly to background (a "near cure") with DRα1-MOG-35-55 blockade of compensatory MIF and CD74-dependent factors known to attract peripheral inflammatory cells into the spinal cord tissue.

An extraordinary relationship involving MIF-1 and other peptides

In commemoration of Abba J. Kastin's exceptional service as the founding editor for the international journal Peptides, I review our collaborative work on how neuropeptides are involved in depression and other neuropsychiatric behavior. A special focus is on MIF-1 (prolyl-leucyl-glycinamide) that was discovered in the Kastin laboratory and shown effective to treat human depression with greater efficacy and faster onset of action than traditional antidepressants at the time of clinical trial. My personal reflection of the evolving changes of translational research on neuropeptides will hopefully provide some insight to young investigators.

Behavioral effects of neuropeptides in rodent models of depression and anxiety

In recent years, studies have advocated neuropeptide systems as modulators for the behavioral states found in mood disorders such as depression and anxiety disorders. Neuropeptides have been tested in traditional animal models and screening procedures that have been validated by known antidepressants and anxiolytics. However, it has become clear that although these tests are very useful, neuropeptides have distinct behavioral effects and dose-dependent characteristics, and therefore, use of these tests with neuropeptides must be done with an understanding of their unique characteristics. This review will focus on the behavioral actions of neuropeptides and their synthetic analogs, particularly in studies utilizing various preclinical tests of depression and anxiety. Specifically, the following neuropeptide systems will be reviewed: corticotropin-releasing factor (CRF), urocortin (Ucn), teneurin C-terminal associated peptide (TCAP), neuropeptide Y (NPY), arginine vasopressin (AVP), oxytocin, the Tyr-MIF-1 family, cholecystokinin (CCK), galanin, and substance P. These neuropeptide systems each have a unique role in the regulation of stress-like behavior, and therefore provide intriguing therapeutic targets for mood disorder treatment.

A Tyr-W-MIF-1 analog containing d-Pro2 discriminates among antinociception in mice mediated by different classes of μ-opioid receptors

The antagonism by Tyr-D-Pro-Trp-Gly-NH2 (D-Pro2-Tyr-W-MIF-1), a Tyr-Pro-Trp-Gly-NH2 (Tyr-W-MIF-1) analog, of the antinociception induced by the mu-opioid receptor agonists Tyr-W-MIF-1, [D-Ala2,NMePhe4,Gly(ol)5]-enkephalin (DAMGO), Tyr-Pro-Trp-Phe-NH2 (endomorphin-1), and Tyr-Pro-Phe-Phe-NH2 (endomorphin-2) was studied with the mouse tail-flick test. D-Pro2-Tyr-W-MIF-1 (0.5-3 nmol) given intracerebroventricularly (i.c.v.) had no effect on the thermal nociceptive threshold. High doses of D-Pro2-Tyr-W-MIF-1 (4-16 nmol) administered i.c.v. produced antinociception with a low intrinsic activity of about 30% of the maximal possible effect. D-Pro2-Tyr-W-MIF-1 (0.25-2 nmol) co-administered i.c.v. showed a dose-dependent attenuation of the antinociception induced by Tyr-W-MIF-1 or DAMGO without affecting endomorphin-2-induced antinociception. A 0.5 nmol dose of D-Pro2-Tyr-W-MIF-1 significantly attenuated Tyr-W-MIF-1-induced antinociception but not DAMGO- or endomorphin-1-induced antinociception. The highest dose (2 nmol) of D-Pro2-Tyr-W-MIF-1 almost completely attenuated Tyr-W-MIF-1-induced antinociception. However, that dose of D-Pro2-Tyr-W-MIF-1 significantly but not completely attenuated endomorphin-1 or DAMGO-induced antinociception, whereas the antinociception induced by endomorphin-2 was still not affected by D-Pro2-Tyr-W-MIF-1. Pretreatment i.c.v. with various doses of naloxonazine, a mu1-opioid receptor antagonist, attenuated the antinociception induced by Tyr-W-MIF-1, endomorphin-1, endomorphin-2, or DAMGO. Judging from the ID50 values for naloxonazine against the antinociception induced by the mu-opioid receptor agonists, the antinociceptive effect of Tyr-W-MIF-1 is extremely less sensitive to naloxonazine than that of endomorphin-1 or DAMGO. In contrast, endomorphin-2-induced antinociception is extremely sensitive to naloxonazine. The present results clearly suggest that D-Pro2-Tyr-W-MIF-1 is a selective antagonist for the mu2-opioid receptor in the mouse brain. D-Pro2-Tyr-W-MIF-1 may also discriminate between Tyr-W-MIF-1-induced antinociception and the antinociception induced by endomorphin-1 or DAMGO, which both show a preference for the mu2-opioid receptor in the brain.

Modulatory effects of PLG and its peptidomimetics on haloperidol-induced catalepsy in rats

A behavioral model of dopaminergic function in the rat was used to examine the anticataleptic effects of L-prolyl-L-leucyl-glycinamide (PLG) and peptidomimetic analogs of PLG. Administration of 1 mg/kg PLG intraperitoneally significantly attenuated haloperidol (1 mg/kg)-induced catalepsy (as measured by the standard horizontal bar test), whereas doses of 0.1 and 10 mg/kg PLG did not. Eight synthetic PLG peptidomimetics (Calpha, alpha-dialkylated glycyl residues with lactam bridge constraint [1-4] and without [5-8]) were tested in the same manner (at a dose of 1 microg/kg) and categorized according to their activity, i.e. very active (5), moderately active (2, 3, 4, and 6), and inactive (1, 7, and 8). The catalepsy-reversal action of the diethylglycine-substituted peptidomimetic 5 was examined further and found to exhibit a U-shaped dose-response effect with an optimal dose of 1 microg/kg. The similarity between the effects of PLG and the synthetic peptidomimetics suggests a common mechanism of action. Finally, the synthetic peptidomimetics examined here, particularly peptidomimetic 5, were more effective than PLG in attenuating haloperidol-induced catalepsy.

Synthesis, stereochemistry, and biological properties of the depigmenting agents, melanostatin, feldamycin and analogs

Syntheses of melanostatin and feldamycin have been completed from L-serine and L-threonine, respectively, and the configuration of unknown asymmetric carbons determined. Feldamycin analogs have also been prepared and the L-tryptophyl analog was the most potent in the depigmentation of Streptomyces bikiniensis and B16 melanoma cells.

[Study of an MPTP-induced parkinsonian animal model in the rhesus monkey and the mechanism of the action of MPTP]

In this paper are presented the data of the use of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to create a parkinsonian animal model in rhesus monkey. We studied the mechanism of the action of MPTP through testing monoamine oxidase B (MAO-B) inhibitor, deprenyl and L-prolyl-L-leucyl-glycinamide (PLG) against the neurotoxicity of MPTP. The results indicated that: (1) the use of MPTP can establish a useful parkinsonian animal model in rhesus monkey; (2) pretreatment with deprenyl can effectively prevent the neurotoxicity of MPTP; and (3) whether PLG can prevent or alleviate the neurotoxicity of MPTP requires further study.

MIF-1 is active in a chronic stress animal model of depression

MIF-1 was tested in an animal model of depression that used unpredictable chronic stress. In this paradigm, rats received either no stressors or a daily protocol of a variety of stressors for 20 days, during which time daily, intraperitoneal injections of various compounds were given. The tricyclic antidepressant imipramine (5 mg/kg) and low doses (0.1 and 1.0 mg/kg) of MIF-1 significantly increased activity and decreased defecation in an open field on day 21. No dose of naloxone (0.01-10.0 mg/kg) acted as an antidepressant. A high dose (10.0 mg/kg) of MIF-1 significantly increased the effects of chronic stress and produced hyperalgesia. Chronically-stressed rats were significantly more analgesic than controls. The results indicate that MIF-1 can act as an antidepressant in this model.

[The action of hypothalamic hormone on athymic mice with transplantable strains of human tumors]

The sensitivity of human melanoma and lung cancer strains transplanted to nude mice to the synthetic hormone of hypothalamus--melanostatin has been defined. Correlation has been noted between the rate of melanoma growth inhibition, decrease in the rate of Na-fluorescent accumulation in the tumor and the tendency towards depression of the activity of energetic metabolism enzymes (SDH and alpha-GPDH) in the treated tumors as compared to control. Moderate lymphopenia and absence of effect on the same enzymes of the lymphocytes was also observed. Fluorescent probes can be used in the estimation of the drug action on the tumor and organs.

L-prolyl-L-leucyl-glycinamide analogues--a new class of peptide antihypertensives

Accumulating evidence suggests that there is an increase in the density (maximum binding sites) of striatal dopamine receptors in the central nervous system of spontaneously hypertensive rats (SHR). A tripeptide of hypothalamic origin, PLG (L-Prolyl-L-Leucyl-Glycinamide) has been found to have modulatory effect on the dopamine receptors in the central nervous system of rats. Two analogues of PLG with cyclic amino-acid residues, L-Prolyl-L-Leucyl-(-)-thiazolidine-2-carboxamide and L-Prolyl-L-Leucyl-(+)-thiazolidine-2-carboxamide, have shown antihypertensive effect at the established phase of hypertension in 16-week old SHRs at a dose of 35 mg/kg per day per 7 days i.p. It was also observed from studies of radioligand [3H]-spiroperidol binding that the laevo-isomer of the PLG analogue has down-regulated the up-regulated dopamine receptors. Our findings confirm the role of central dopaminergic pathways in the pathogenesis of hypertension in SHR.

CNS dopamine receptors: effect of prolyl-leucyl-glycinamide and solubilization

In order to elucidate the mechanism of interaction of a peptide L-prolyl leucyl-glycinamide (PLG) with dopamine receptors, we have studied the action of PLG on dopamine receptors in various brain regions. The results support the hypothesis that specific PLG binding sites exist in the central nervous system and these binding sites (receptors) have a modulatory effect on the sensitivity of dopamine receptors. It is also suggested that PLG and its active analogues warrant further vigorous and systematic clinical trials to establish their therapeutic efficacy in Parkinson's disease, neuroleptic drug induced tardive dyskinesia and related extrapyramidal motor disorders. Studies carried out on solubilized dopamine receptors and adenylate cyclase suggest that dopamine receptors sites coupled to neurolic drug action and adenylate cyclase linked receptor sites might be closely interrelated. The preliminary results on lymphocyte dopamine binding sites suggest an increase in binding in schizophrenic patients, however, receptor criteria (stereospecific binding, saturation, etc.) could not be met for these binding sites (see Rotstein et al., 1983, for details).

Rapid clinical effectiveness of MIF-I in the treatment of major depressive illness

A double-blind 28 day study was conducted to compare the anti-depressant efficacy of MIF-I with that of imipramine. Twenty patients hospitalized with major depressive illness participated. Clinical responses were measured by using the Hamilton Depression Rating Scale, the Global Severity of Illness Scale, the Zung Self-Rating Depression Scale as well as the 100 mm line self-rating for depression. The results indicate that MIF-I was at least as effective as imipramine in this study, and that its anti-depressive effect was a rapid and often dramatic one.

Peptide challenges in affective illness

Peptides regulate neuroendocrine and limbic system functioning in animals. Both systems show major disturbances in the affective disorders. Only thyrotropin releasing hormone (TRH), luteinizing hormone releasing hormone (LHRH), melanocyte stimulating hormone inhibiting factor (MIF-I), and 1-desamino-8-D-arginine vasopressin (DDAVP) have been administered to affectively ill patients. The thyroid stimulating hormone (TSH) response to TRH is blunted (less than or equal to 5 microU/ml) in some patients during depression and mania and in alcoholics. The blunted response may be an important tool in the diagnosis of depression and mania. Together with other demonstrated endocrine abnormalities, the blunted TSH response suggests a profound alteration in the physiological relationship between the central nervous system and the anterior pituitary in affective illness. Behaviorally, TRH, LHRH, DDAVP, and MIF-I have general activating effects in human that have not yet been demonstrated to be restricted to or specific to affective illness. The interpretation of peptide challenges, however, in the study of affective illness is obfuscated by the small number of patients used and the multiple sites that peptides at pharmacological doses may affect.

Effects of Pavlovian conditioning and MIF-I on the development of morphine tolerance in rats

Thirty male Sprague-Dawley-derived rats were given daily IP injections of morphine (5.0 mg/kg) in the presence of a specific set of environmental cues for eleven consecutive days. Twelve hours after each morphine session, a control injection was given in a different environment. On Day 12 through 14 the environmental cues associated with each session were reversed. On Day 15 environmental cues associated with each session were the same as on Days 1-11. Analgesia was assessed by the tail-flick method 30 minutes after each morphine and control injection. Four independent groups (n=6) received either a lower (0.1 mg/kg) or a higher (5.0 mg/kg) dose of MIF-I either 10 minutes before or immediately after each morphine and control session. A control group received an injection of a diluent vehicle both before and after each session. None of these peptide-treatments significantly affected either acute action of morphine or the development of tolerance across days. Tail-flick latencies from both morphine and control sessions significantly decreased across days. On Day 12, when morphine was administered in the presence of cues not previously associated with its administration, tail-flick latencies were significantly longer than on the previous day. Tail-flick latencies did not change from Day 11 to Day 15 during control sessions. Morphine-session latencies did not change from Day 14 to Day 15, although they did decrease from Day 12 to Day 14. The significant morphine-induced analgesia on Day 15 of the experiment increases a remarkable resistance to the development of tolerance to morphine. The results partially support the hypothesis proposed by Siegel [115-18] that principles of Pavlovian conditioning exert an important influence on the development of tolerance to morphine.

Antagonistic actions of MIF-I on the hypothermia and hypomotility induced by beta-endorphin or morphine

Recently it has been suggested that MIF-I can act as an opiate antagonist for analgesia. Therefore, rats kept at 4 degrees C were pretreated with MIF-I in an attempt to extend the observation to a nonanalgesic opiate effect by determining any blockade of the thermal response to beta-endorphin and morphine. MIF-I, at an ip dose of 1.0 mg/kg, was found to block the thermal responses to beta-endorphin injected ip at doses of 0.1 and 1.0 mg/kg. A lower dose (0.1 mg/kg, ip) of MIF-I, or naloxone (10 mg/kg), was also able to block the thermal effects of 30 and 60 mg/kg doses of morphine. However, an ip dose of 1.0 mg/kg MIF-I potentiated the hypothermic effects of morphine but, like naloxone, reduced the magnitude of the decrease in the level of motor activity induced by beta-endorphin or by morphine. The results of this study demonstrate a nonanalgesic situation in which MIF-I can act as an antagonist of opiate effects after peripheral injection.

Failure of MIF-I to affect behavioral responses in patients with Parkinson's diseases under L-dopa therapy

In eight subjects with Parkinson's disease under an optimal daily dose of L-dopa, acute administration of MIF-I (200 mg i.v.) did not ameliorate either the total disability score or the intellectual test PM 38 when evaluated in comparison with the effect induced by acute administration of a placebo. Also concomitant evaluation of the effect of MIF-I on the secretion of anterior pituitary hormones which are under dopaminergic control i.e., growth hormone and prolactin, did not reveal any potentiation of the L-dopa-induced stimulus.

Dose-related biphasic effect of prolyl-leucyl-glycinamide (MIF-I) in depression

Five of 8 patients with unipolar or bipolar endogenous depressions taking prolyl-leucyl-glycinamide (MIF-I), 75 mg/day, showed substantial improvement within a few days of beginning treatment compared with similar improvement in only 1 of 10 receiving 750 mg/day of MIF-I and only 1 of 5 patients taking placebo. The lower dose of MIF-I was associated with significantly greater improvement than both the higher dose and placebo on all of the rating scales used. The authors suggest that an even lower dose of MIF-I, on the order of 0.1 mg/kg, may have a greater effect as an antidepressant.

[Physiological trials with MIF-I in Parkinson's disease (author's transl)]

The writers present some physiological (and not therapeutic) acute and sub-acute trials with tripeptide: L-propyl-L-leucyl-glycine amide (M.I.F.-I) in Parkinson's Disease. This work confirms the earlier observation that M.I.F.-I employed alone or in combination with Levodopa is active against Parkinson's disease. The writers evoke the hypothesis that this action takes place at the postsynaptic receptors, whose configuration may be modified in the sense of a hypersensitivity. These studies justify undertaking a series of controlled therapeutic trials when the cost of the product permits and as well instituting development work on analogues active orally.

Synthetic MIF has no effect on beta-MSH and ACTH hypersecretion in Nelson's syndrome

The effect of synthetic MIF (H-Pro-Leu-Gly-NH2) on beta-MSH secretion was studied in five patients with Nelson's syndrome and in one patient with Addison's disease. Two milligrams of the tripetide were injected intravenously (1 mg in an acute injection, followed by a 30-minute-infusion of 1 mg in 20 ml of saline solution). No consistent effect could be observed during the 90-minute period after the beginning of the infusion. In the same patients, LVP stimulation and dexamethasone suppression tests brought about significant changes in the plasma beta-MSH and ACTH levels.

Double-blind evaluation of oral L-prolyl-Lleucyl-glycine amide in Parkinson's disease

A 4-month double-blind study comparing the effect of increasing oral doses (up to 1.0 g daily) of synthetic L-proyl-L-leucyl-glycine amide (PLG) and placebo in 20 parkinsonian patients showed no significant improvement in objective scores of functional disability. However, important trends and some significant results were observed with the lower doses of PLG. These essentially negative results may be attributed to poor intestinal absorption of the compound, a short biologic half-life in the blood, or administration of oral doses that were much higher than required, or a combination of factors. In further studies with this peptide, which are encouraged, the intravenous route should be used until the question of intestinal absorption is resolved.

Clinical investigations for emotional effects of neuropeptide hormones

After the demonstration that hypothalamic peptides can have a direct effect on the central nervous system, a series of studies was initiated to investigate the hypothesis that hypothalamic peptides could have an effect on emotions and affect. TRH was administered to 6 patients with endogenous depressions in a double-blind, cross-over design with transient improvements in the mental depression of 4 of the 6 patients. In a second study involving 8 seriously depressed patients given 1000 mug of TRH for 10 days, no significant antidepressant effect of TRH was observed. In a pilot, double-blind study of 18 women with endogenous depressions, the group receiving MIF-1 60 mg per day in a single daily dose for 6 days responded better than the placebo group, which in turn responded better than the group receiving MIF-1 150 mg per day. In a second, double-blind study testing MIF-1 in endogenous depressions, 5 patients met the criteria for substantial improvement out of a total of 8 receiving MIF-1 75 mg per day. In contrast, only one patient met these criteria in each of the remaining 2 groups, consisting of 10 patients receiving MIF-1 750 mg per day and 5 patients receiving placebo. Finally, 6 men complaining of decreased libido and/or potency were given intravenous injections of LHRH 700 mug or saline once daily for 3 consecutive days per week in a double-blind, cross-over design. In addition, 3 men were given much higher doses of LHRH in a single-blinded study. No substantial effect on libido or sexual performance was observed.

[Infusion therapy with mif (melanocyte inhibiting factor) in Parkinson's disease (author's transl)]

On the basis of reports in the literature and of our own clinical experience it appears that melanocyte inhibiting factor (MIF) is a very promising therapeutic agent in the management of Parkinson's disease. Besides theoretical considerations relating to biochemical and pathophysiological spheres, the question of the current dosage for clinical usage seems to be of the utmost importance. We are of the opinion that the currently-employed dosage of 400 mg daily is still too low. Hence, the present investigation will be continued with a view to establishing the optimum dosage for maximal therapeutic effect.