Stress-induced hypokinesia is facilitated by ACTH-(7-10)

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.

New vistas for melanocortins. Finally, an explanation for their pleiotropic functions

This paper presents a historical overview of melanocortin (MC) research from the early investigations of the many noncorticotropic effects of peptide fragments of adrenocorticotropic hormone to the present focus on the discovery and cloning of the MC receptors (MCRs). Final acceptance of the passage of neuropeptides through the blood-brain barrier provided the scientific basis for the neuropeptide concept, formulated previously by both De Weid and Kastin, that peripherally administered neuropeptides affect neural processes. The discussion includes melanocortin effects on behavior, the cardiovascular system, central and peripheral electrophysiological parameters, food intake, inflammation and analgesia, nerve regeneration and neuroprotection, and development. The localization of specific MCRs in both neural and nonneural tissues is correlated with the pleiotropic effects discussed.

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.

Opioid systems in the amygdala can serve as substrate for the behavioral effects of the ACTH-(4-9) analog ORG 2766

Rats housed individually for 7 days showed a marked decrease in motor activity when tested under intense light conditions in a novel environment as compared to group-housed rats tested under low light conditions. The ACTH analogue ORG 2766 administered into the amygdala decreased the motor activity of group-housed rats tested under low light conditions and increased the motor activity of 7-days isolated rats tested under intense light conditions (ED50: 1-10 pg). Injection of the peptide into the nucleus accumbens was not effective, suggesting that ORG 2766 affects the integration of sensoric stimuli rather than the specific motor output systems. Pretreatment of the rats with the opiate antagonist naltrexone in the amygdala completely blocked the effect of ORG 2766. A similar blockade of the ORG 2766-induced effect could be induced by pretreatment with endorphin antibody suggesting that the "normalizing" activity of ORG 2766 on environmentally induced behavioral changes is mediated by the release of endogenous opioid peptides.

Behavioral and neurotrophic activity of ACTH-(7-16)NH2

The behavioral and neurotrophic effects of ACTH-(7-16)NH2 were assessed in a number of tests in which other ACTH fragments are active. Subcutaneous injection of ACTH-(7-16)NH2 increased motor activity of group-housed rats tested under low light intensity and induced hypokinesia in rats subjected to the mild stress of a nonfunctional "hot" plate. In rats with 6-OHDA lesions in the nucleus accumbens daily subcutaneous treatment with ACTH-(7-16)NH2 during the first week following the lesions reversed the lesion-induced motor hypoactivity. The ED50's for the effects of ACTH-(7-16)NH2 on the environmentally induced changes in motor activity, the stress-induced hypokinesia and the impaired motor activity of 6-OHDA lesioned rats were approximately 8 micrograms/kg. 6.3 micrograms/kg and 0.45 micrograms/kg respectively. It is concluded that ACTH-(7-16)NH2 may mimic the effect of an ACTH-like peptide in the brain involved in brain processes triggered by changes in the environment and by brain damage.