Effects of ACTH(1-24) and ACTH/MSH(4-10) on isolation-induced distress vocalization in domestic chicks

The effects of centrally administered ACTH(1-24) and ACTH(4-10) on isolation-induced distress vocalizations (DVs) were assessed in the presence or absence of social cues (mirrored and plain environments). A dose-response analysis indicated that ACTH(1-24) at doses of 0.5 nM and above increased DVs relative to controls when the animals were tested in mirrored or social environments which reduce baseline levels of calling. This effect, however, was short-lived (approx. 15 min). When tested again 1 hr after injection, the treated animals did not differ from controls. ACTH/MSH(4-10) had no effect on vocalization when the animals were tested immediately after injection, but marginally increased calling when animals were tested an hour later. In addition to vocalization changes, ACTH(1-24) induced squatting when animals were isolated in the test boxes, and yawning, head shaking, wing flapping and preening when animals were reunited after testing. ACTH(1-24)-treated chicks also exhibited longer latencies to close their eyes when they were held in the cupped hands of the experimenter. Taken together, the results suggest that ACTH(1-24) induces a central state of arousal in chicks that resembles fear/anxiety.     

Antiparallel beta-sheets in the crystal structure of the heptapeptide Met-Glu-His-Phe-Arg-Trp-Gly (ACTH 4-10)

The conformation of the molecules in ACTH 4-10 has been determined as part of a study of the conformations of the biologically active N-terminal fragments of the adrenocorticotropic hormone (ACTH). ACTH 4-10 crystallizes in two different superstructures. The substructure considered in the present work, is monoclinic, space group C2, a = 25.75(1) A, b = 27.78(1) A, c = 20.35(1) A, beta = 114.0(1) degrees, Z = 8 molecules ACTH 4-10 plus 22 weight per cent solvent. The crystals contain antiparallel beta-sheets, the orientations of the side groups are not found, because of disorder. The present crystal structure and those of other linear oligopeptides emphasize that antiparallel beta-sheets are energetically favourable. It is very unlikely, however, that the ACTH 4-10 crystals contain the molecules in their biologically active form.     

Centrally administered N-terminal fragments of ACTH (1-10, 4-10, 4-9) display convulsant properties in rabbits

Electroencephalographic and behavioral effects of the following ACTH fragments: 1-4, 4-9, 4-11, 1-10, 4-10, 1-13, 1-17 and 1-24 were studied in rabbits. Sequences 4-9, 1-10 and 4-10 displayed some epileptic properties, i.e., they induced epileptic seizures (only electrographic or also behavioral) or increased hippocampal spiking. The 4-9 sequence seemed to be the common sequence responsible for these proconvulsant effects. The possible involvement of the enkephalinergic system is discussed.     

ACTH/MSH(4-10) peptide increases postnatal metabolic activity of EDL muscle following early prenatal administration

ACTH/MSH(4-10) (10 micrograms/kg/b.i.d.; IP), administered to pregnant Sprague-Dawley rats during gestational days (GD) 3 to 12, significantly increased the metabolic activity of extensor digitorum longus (EDL) muscle at postnatal day 14. ACTH/MSH peptide, administered from day of birth to postnatal day 13, had no effect on EDL muscle metabolic activity using the 2,3,5-triphenyltetrazolium chloride indicator. By postnatal day 30, no differences were seen between the early prenatally treated group and saline controls. These results confirm our previous electrophysiological studies that showed that early prenatal ACTH/MSH(4-10) administration accelerates EDL muscle maturation.     

Effect of (L-Phe7) and (D-Phe7) ACTH 4-7 and an ACTH 4-7 analog with prolonged action on acetylcholinesterase activity in the rat brain

ACTH4-7 and its long-acting analog stimulate acetylcholinesterase activity of different areas of the rat brain. Based on the data concerning the effect of an amino acid mixture equivalent to ACTH4-7 and actinomycin D on acetylcholinesterase activity of the white substance of the large hemispheres it is inferred that the oligopeptide-induced increase in the enzyme activity is linked with the induction of the synthesis of new acetylcholinesterase molecules.     

Chemico-enzymatic synthesis of an oligonucleotide template for an analog of ACTH (4-10) fragment

Six oligodeoxyribonucleotides ranging from 9-mer to 13-mer were synthesized in solution by the phosphotriester approach and enzymatically joined by T4 DNA ligase. The obtained double-stranded DNA (32 b.p.) with protruding 5'-ends corresponding to the recognition sites for restrictases EcoRI and BamHI represents an oligonucleotide template coding for the modified amino acid sequence 4-10 of the adrenocorticotropic hormone, [Pro8,Gly9,Pro10]ACTH-(4-10).     

Dependence of long-lasting effects of the ACTH(4-10) analogue semax on the time of its neonatal administration

Long-lasting behavioural effects of chronic administration of synthetic ACT(4-10) analogue Semax (MEHFPGP) during early neonatal life were studied. The peptide was injected daily intraperitoneally in dose 0.05 mg/kg during the first, second or second-third weeks of postnatal development. It was shown that the peptide injections during the first week lead to a decrease and during second or second-third weeks--to an increase of exploratory activity in 4-8-week aged rats. Furthermore, the peptide adminictration at all times diminished anxiety and improved learning ability of adult rats. The data obtained show that Semax neonatal administration during the first three weeks of life modulates development of brain structures involved in regulation of exploration, anxiety and learning.     

Anticipated and unexpected physiological effects of oligopeptides (glyprolines, ACTH (4-10) analogs, taftsin, and thyroliberin)

A short review of investigations resulting in determination of a new family of regulatory peptides (glyprolines) participating in modulation of hemostasis and protection of mucous membranes, obtaining of the ACTH4-10 new analogues which are potent neuroprotectors and nootrops, and revealing of unexpected biological activities of some other peptides (behavioural effects of tuftsin, lymph flow stimulation by thyroliberin, etc.). Further investigations into the functional peptide continuum is discussed.     

Naltrexone-sensitive behavioral actions of the ACTH 4-9 analog (Org 2766)

The effects of the ACTH 4-9 analog (Org 2766) and the COOH-terminal tripeptide of Org 2766 (Phe-D-Lys-Phe; PDLP) on retrieval of one-trial learning passive avoidance behavior were compared with those of beta-endorphin, [Met5]-enkephalin, [D-Ala2,Met5]-enkephalin, des-Tyr1-[Met5]-enkephalin and des-enkephalin-gamma-endorphin (DE gamma E). Amounts of intracerebroventricularly administered Org 2766, PDLP, [Met5]-enkephalin, [D-Ala2,Met5]-enkephalin and DE gamma E, which induced a comparable attenuation of passive avoidance behavior were determined. Pretreatment with the opiate antagonist naltrexone prevented the attenuating effect of these peptides on passive avoidance behavior except that of DE gamma E. The attenuating effect of Org 2766 and of [Met5]-enkephalin was reversed to facilitation of passive avoidance behavior in the presence of naltrexone. Subcutaneous treatment with Org 2766 and [D-Phe7]-ACTH 4-10 decreased electrical self-stimulation behavior elicited from the medial septal area. Naltrexone prevented the inhibitory effect of Org 2766 on this behavior, but not that of [D-Phe7]-ACTH 4-10. Although the attenuating effect of PDLP on passive avoidance behavior was not reduced by pretreatment with [Met5]-enkephalin- or beta-endorphin-antiserum, and PDLP induced neither analgesia nor excessive grooming, the data suggest that the inhibitory effect of Org 2766 and PDLP on passive avoidance behavior and electrical self-stimulation are mediated by endorphin systems in the brain.     

Behavioral activity of met-enkephalin and ACTH4-10 and other peptides containing a phenylalanine and methionine residue

Met-enkephalin, injected i.p. 5 minutes before training, decreased acquisition of a step-up active avoidance response in rats. ACTH_4–10 exerted a similar effect if given i.p. within 15 minutes of training. ACTH_4–10 and Met-enkephalin share a phenylalanine and a methionine residue. The possibility was studied that these amino acid residues are a structural requirement for this effect. Accordingly, some linear and cyclic peptides sharing the sequence Phe-Met were synthesized and tested. The cyclic peptide $\text{cyclo}$ (-Phe-Met-ε-Ahx-) decreased acquisition but with a longer time course of efficacy than for ACTH_4–10 or Met-enkephalin and also after oral administration.     

Development in ontogeny of the effect of ACTH fragment 4-7 on rat learning

Studies have been made of the effect of ACTH fragment 4-7 on learning in rats in early postnatal ontogenesis, as well as of the possibility of preservation of early learning during administration of this peptide to adult animals. It was shown that conditioned reaction of active avoidance practically cannot be formed in normal 13-15-day animals; however, administration of ACTH 4-7 increases the number of animals exhibiting adequate reactions. Weak effect of ACTH 4-7 in 12-15-day animals, in older ones (20-24 days) is changed by a significant stimulating effect.     

Long-lasting behavioral effects of chronic neonatal treatment with ACTH (4-10) analogue semax in white rat pups

It is well known that ACTH/MSH-like peptides (melanocortins) have neurotrophic and neuroprotective effects on the central and peripheral nervous systems in the early postnatal life. The aim of present work was to study consequences of the ACTH (4-10) analogue Semax influence on the developing brain. The work was carried out in white rat pups. The peptide (0.05 mg/kg, i/p) was injected daily on the 8th-21st postnatal days. Delayed long-lasting effects of such treatment on animal behavior were revealed. At the age of four to eight weeks, Semax-treated rats displayed elevated exploratory activity, decreased anxiety level and improved passive avoidance conditioning. The results suggest that neonatal Semax administration modulates the development of the central nervous system.     

Effect of ACTH1-24 and ACTH4-10 on distribution of 3H-noradrenaline in the brain of adrenalectomized rats.

Painful stimuli led to a decrease of the radioactive catecholamine pool in adrenalectomized rats. Intraventricular administration of both tritiated noradrenaline and ACTH produced a greater decrease of the labelled catecholamine pool than in the control adrenalectomized rats in 12 to 18 hr following injection. Blocking of monoamino-oxidase activity or biosynthesis by systemic administration of Pargyline or alpha-methyl-tyrosine did not prevent the effect of ACTH on brain catecholamines. It is concluded that ACTH exerts a direct influence on the brain catecholaminergic system and that this effect might be involved in ACTH dependent behavioural responses.     

Degradation of the ACTH(4-10) analog Semax in the presence of rat basal forebrain cell cultures and plasma membranes

Summary. Here a new approach of the elucidation of paths of proteolytic biodegradation of physiologically active peptides, based on the use of a peptide with isotopic label at all amino acid residues and the enrichment of HPLC samples with unlabeled peptide fragments in UV-detectable concentration, has been proposed. The method has been applied for the investigation of degradation dynamics of the neuroactive heptapeptide MEHFPGP (Semax) in the presence of plasma membranes, and cultures of glial and neuronal cells obtained from the rat basal forebrain. The splitting away of ME and GP, and formation of pentapeptides are the predominant processes in the presence of all tested objects, whereas the difference in patterns of resulting peptide products for glial and neuronal cells has been detected. In conclusion, the approach applied allows analyzing physiologically active peptide concentrations in biological tissues and degradation pathways of peptides in the presence of targets of their action.     

Effect of ACTH 4-10 on passive avoidance of rats lacking vasopressin (Brattleboro strain).

The hypothesis that the effects of ACTH 4-10 on avoidance are mediated via the release of endogenous vasopressin was investigated. To test this hypothesis, we observed the effect of ACTH 4-10 on the passive avoidance of Brattleboro rats with diabetes insipidus resulting from a total genetic deficiency of vasopressin (DI) and Brattleboro rats without diabetes insipidus (HE). Normal Long-Evans rats (LE) were also included for comparison purposes. The results did not support the hypothesis. ACTH 4-10 did influence the passive avoidance of DI rats; this should not have occurred if the release of endogenous vasopressin is necessary for ACTH 4-10 to influence avoidance.