The dipeptide Lys-Pro attenuates interleukin-1 beta-induced anorexia

New melanocortin 1 receptor binding motif based on the C-terminal sequence of alpha-melanocyte-stimulating hormone

The C-terminal tripeptide of the alpha-melanocyte stimulating hormone (alpha-MSH11-13) possesses strong antiinflammatory activity without known cellular target. In order to better understand the structural requirements for function of such motif, we designed, synthesized and tested out Trp- and Tyr-containing analogues of the alpha-MSH11-13. Seven alpha-MSH11-13 analogues were synthesized and characterized for their binding to the melanocortin receptors recombinantly expressed in insect (Sf9) cells, infected with baculovirus carrying corresponding MC receptor DNA. We also tested these analogues on B16-F1 mouse melanoma cells endogenously expressing the MC1 receptor for binding and for ability to increase cAMP levels as well as on COS-7 cells transfected with the human MC receptors. The data indicate that HS401 (Ac-Tyr-Lys-Pro-Val-NH2) and HS402 (Ac-Lys-Pro-Val-Tyr-NH2) selectively bound to the MC1 receptor and stimulated cAMP generation in a concentration dependent way while the other Tyr- and Trp-containing alpha-MSH11-13 analogues neither bound to MC receptors nor stimulated cAMP. We have thus identified new MC receptor binding motif derived from the C-terminal sequence of alpha-MSH. The tetrapeptides have novel properties as the both act via MC-ergic pathways and also carry the anti-inflammatory alpha-MSH11-13 message sequence.

Effects of peptides on animal and human behavior: a review of studies published in the first twenty years of the journal Peptides

This review catalogs effects of peptides on various aspects of animal and human behavior as published in the journal Peptides in its first twenty years. Topics covered include: activity levels, addiction behavior, ingestive behaviors, learning and memory-based behaviors, nociceptive behaviors, social and sexual behavior, and stereotyped and other behaviors. There are separate tables for these behaviors and a short introduction for each section.

Infection-induced anorexia: active host defence strategy

In association with fever production, decreased food consumption is the most common sign of infection. This effect is often regarded as an undesirable manifestation of sickness. However, evidence suggests that just as many behaviours have now been shown to modify immunocompetence, infection-induced anorexia is a behaviour systematically organised for pathogen elimination. That is, anorexia is an active defence mechanism that is beneficial for host defence. This review details the mechanism of infection-induced anorexia, placing it within the framework of the intricately organised acute phase response--the host response to infection. Furthermore, the evolutionary, behavioural, metabolic and immunological consequences of infection-induced anorexia are outlined, each providing evidence for the beneficial nature of this response. The evidence suggests that food restriction is one of the important behavioural strategies that organisms have evolved for the fight against pathogenic invasion. Nevertheless, such benefits require fine homeostatic control, as chronic undernutrition has deleterious consequences for host defence.

Induction of interleukin-1 and glucocorticoid hormones by HIV promotes viral replication and links human chromosome 2 to AIDS pathogenesis: genetic mechanisms and therapeutic implications

Human immunodeficiency virus may regulate its replication by stimulating the synthesis of interleukin-1. Interleukin-1, in turn, has the ability to stimulate the human immunodeficiency virus enhancer region. The human genes responsible for interleukin-1 and interleukin-1 receptor antagonist synthesis are located on the long arm of chromosome 2. Coincidentally, the trans-activation responsive ribonucleic acid element in the R region of the long terminal repeat of human immunodeficiency virus-1 has been found to interact directly with a factor present on the long arm of chromosome 2 to facilitate transactivation by the human immunodeficiency virus Tat protein. The human CD26 gene is also located on the long arm of chromosome 2. CD26 is a lymphocyte cell surface antigen that is stimulated by interleukin-1 and serves with CD4 as a coreceptor that interacts with the V3 loop in gp120 of human immunodeficiency virus. The human immunodeficiency virus-induced interleukin-1 excess, thus, serves human immunodeficiency virus by enhancing replication, and by increasing human immunodeficiency virus infectivity via activation of CD26. IL-1 also adversely affects acquired immune deficiency syndrome-related Kaposi's sarcoma. Several genetic treatments for human immunodeficiency virus infection are proposed.

Acquired immune deficiency syndrome: the glucocorticoid solution

Documented evidence supports the "cortisol connection' theory of acquired immune deficiency syndrome, linking glucocorticoid metabolism with immune function, and human immunodeficiency virus with them both. The peptide T subregion of gp 120 of human immunodeficiency virus apparently utilizes cellular melanocyte stimulating hormone receptors to competitively inhibit the blocking of interleukin-1 by melanocyte-stimulating hormone. Interleukin-1 stimulates CD8+ T-lymphocyte proliferation, as well as causing the release of corticotropin-releasing hormone, thereby stimulating the release of adrenocorticotrophic hormone and cortisol. Gp 120 also induces upregulation of adrenocorticotrophic hormone-related messenger ribonucleic acid. This apparently separate glucocorticoid metabolic route utilized by human immunodeficiency virus is the basis of the cortisol excess seen in human immunodeficiency virus infection. In vitro glucocorticoid-resistant lymphoid cells are resistant to human immunodeficiency virus infection as well. Viral resistance is also observed in patients who demonstrate glucocorticoid resistance. Glucocorticoid-responsive elements are contained in the human immunodeficiency virus (proviral and viral) genome that appear to regulate human immunodeficiency virus replication. Similarly, lymphoid-cell development and regulation depend on glucocorticoids. One may take advantage of this view of human immunodeficiency virus pathogenesis to create new methods of treatment.

Antinociceptive activity of peptides related to interleukin-1 beta-(193-195), Lys-Pro-Thr

A series of closely related peptide analogues of Lys-Pro-Thr [(interleukin-1 beta-(193-195)] have been investigated in two models of antinociception in mice (acetic acid-induced abdominal constrictions and formalin tests) and compared with morphine, aspirin and indomethacin. Formalin-induced nociceptive responses in the mouse showed early (0-5 min) and late (15-30 min) phases of peak activity. Lys-D-Pro, Lys-D-Pro-Thr, Lys-D-Pro-Arg, Lys-D-Pro-Val, morphine and aspirin, were antinociceptive in both phases after intraperitoneal (i.p.) and oral (p.o.) administrations. Lys-D-Pro-Leu inhibited the early phase response only after i.p. injection. Lys-D-Pro-Val-NH2, Lys-D-Pro-Gln, Lys-D-Pro-Tyr, Lys-D-Pro-Asn, Asp-Lys-D-Pro-Val and indomethacin were active only against the late phase (ED50 values of 64, 32, 44, 94, 67 and 25 mg/kg i.p., respectively). Several of the peptides showed good bio-availability, e.g. Lys-D-Pro-Asn (ED50: 10 mg/kg i.p.; 11.4 mg/kg p.o.) in the abdominal constrictions test, where two modes of action were apparent, non-opioid and opioid; non-opioid (naloxone-insensitive antinociception) mechanisms were illustrated by Lys-D-Pro-Thr and Lys-D-Pro-Asn; opioid (naloxone-sensitive antinociception) mechanisms by Lys-D-Pro-Val and Lys-D-Pro-Leu. These data identify orally active antinociceptive peptides in both antinociceptive tests with varied relative potency profiles to morphine, indomethacin and aspirin in the mouse formalin test.

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.