An ACTH4-9 analog enhances social attention in aging rats: a longitudinal study

Reproducibility and relevance of future behavioral sciences should benefit from a cross fertilization of past recommendations and today's technology: "Back to the future"

Thanks to the discovery of novel technologies and sophisticated analysis tools we can now 'see' molecules, genes and even patterns of gene expression, which have resulted in major advances in many areas of biology. Recently, similar technologies have been developed for behavioral studies. However, the wide implementation of such technological progress in behavioral research remains behind, as if there are inhibiting factors for accepting and adopting available innovations. The methods of the majority of studies measuring and interpreting behavior of laboratory animals seem to have frozen in time somewhere in the last century. As an example of the so-called classical tests, we will present the history and shortcomings of one of the most frequently used tests, the open field. Similar objections and critical remarks, however, can be made with regard to the elevated plus maze, light-dark box, various other mazes, object recognition tests, etc. Possible solutions and recommendations on how progress in behavioral neuroscience can be achieved and accelerated will be discussed in the second part of this review.

Oxytocin increases the influence of public service advertisements

This paper presents a neurophysiologic model of effective public service advertisements (PSAs) and reports two experiments that test the model. In Experiment 1, we show that after watching 16 PSAs participants who received oxytocin, compared to those given a placebo, donated to 57% more causes, donated 56% more money, and reported 17% greater concern for those in the ads. In Experiment 2, we measured adrenocorticotropin hormone (ACTH) and oxytocin levels in blood before and after participants watched a PSA. As predicted by the model, donations occurred when participants had increases in both ACTH and oxytocin. Our results indicate that PSAs with social content that cause OT release will be more effective than those that do not. Our results also explain why some individuals do not respond to PSAs.

Postnatal treatment with ACTH-(4-9) analog ORG 2766 attenuates N-methyl-D-aspartate-induced excitotoxicity in rat nucleus basalis in adulthood

It has been reported that the ACTH-(4-9) analog H-Met(O(2))-Glu-His-Phe-D-Lys-Phe-OH (ORG 2766) administered in adulthood has trophic effects on neuronal tissue and when given postnatally, it can induce long-lasting changes in brain development. In the present study, we investigated whether early postnatal treatment with ORG 2766 affects adult neuronal vulnerability, i.e. the sensitivity of cholinergic neurons against excitotoxic damage. Wistar rat pups received injections of ORG 2766 or saline on postnatal days 1, 3 and 5 and were then left undisturbed until adulthood. At the age of 6 months, the animals were subjected to unilateral lesion of magnocellular basal nucleus by infusion of high dose of N-methyl-D-aspartate (NMDA). The effects of the excitotoxic insult were studied 28 hours and 12 days after the lesion by measuring both the acute cholinergic and glial responses, and the final outcome of the degeneration process. Twenty eight hours after NMDA infusion, postnatally ACTH-(4-9)-treated animals showed stronger suppression of choline-acetyltransferase immunoreactivity and increased reaction of glial fibrillary acidic protein -immunopositive astrocytes in the lesioned nucleus compared to control animals. However, 12 days post-surgery, the NMDA-induced loss of cholinergic neurons, as well as the decrease of their acetylcholinesterase -positive fibre projections in the cortex, were less in ACTH-(4-9) animals. Our data indicate that the early developmental effects of ACTH-(4-9) influence intrinsic neuroprotective mechanisms and reactivity of neuronal and glial cells, thereby resulting in a facilitated rescuing mechanism following excitotoxic injury.

Behavioral pharmacology of neuropeptides related to melanocortins and the neurohypophyseal hormones

Neuropeptides are peptides which affect the nervous system. They are derived from large precursor molecules. These are converted to neurohormones, neuropeptides of the "first generation", which can be further converted to neuropeptides of the "second generation". This review is a brief survey of the nervous system effects of neuropeptides derived from pro-opiomelanocortin (POMC) and the neurohypophyseal hormones. Processing of these molecules results in neuropeptides of the first and second generation which have similar, different, more selective or even opposite effects. Among those are effects on learning and memory processes, grooming, stretching and yawning, social, sexual and rewarded behavior, aging and nerve regeneration, thermoregulation, pain, sensitivity to seizures, and cardiovascular control. Results of animal studies as well as those of clinical studies suggest that these neuropeptides may be beneficial in aging, neuropathy, memory disturbances and schizophrenia. Most of these nervous system effects in animal studies were found before receptors in the nervous system for the various neuropeptides were detected. G-protein-coupled receptors for the neuropeptides of the "first generation", i.e., melanocortin receptors, opioid receptors, and neurohypophyseal hormone receptors have been found, in contrast to the receptors for neuropeptides of the "second generation", although there are indications that G-protein coupled receptors for these may be present in the brain.

Animal models in the development of symptomatic and preventive drug therapies for Alzheimer's disease

Dementia of the Alzheimer type (AD) is clinically characterized by a progressive deterioration of intellect, memory, judgment, and abstract thinking. It is incurable, and causal therapy is not yet available. For the development of therapeutic drugs, valid animal models are needed that mimic the pathophysiological change in brain functions and the concomitant behavioural deterioration seen in AD patients. This article provides an overview of the animal models that are used most often to study the substrates and mechanisms of the pathological changes underlying AD and to identify, characterize and develop putative neuroprotective, antidegenerative, revalidation-supporting and/or cognition-enhancing compounds or treatments. The first generation of agents for the symptomatic treatment of the disease has been developed on the basis of results obtained with these models. These drugs are presently undergoing clinical testing or are already used therapeutically. There is, however, no single animal model that can mimic the full range of pathophysiological alterations and key symptoms of AD. New, genetically engineered mouse models that mimic at least some of the key pathological changes of AD are expected to provide tools that will facilitate the development of symptomatic and preventive drug therapies.

The ACTH(4-9) analog ORG 2766 and recovery after brain damage in animal models--a review

Treatment with adrenocorticotrophic hormone (ACTH), as well as with ACTH fragments and analogues, can influence behaviour of animals and humans. Furthermore it facilitates recovery of damaged peripheral nervous tissue. The question whether ACTH/MSH peptides affect recovery processes after injury to the central nervous system as well is addressed in the present review. The effects of administration of the ACTH(4-9) analog ORG 2766 after brain lesions has been studied frequently. However, the interpretation of the available data is confused by the variability of the results. Several factors can be identified which influence the efficacy of the peptide: (i) not all behavioural tests are equally suitable to reveal a peptide effect on behavioural recovery; (ii) the affected brain area; (iii) whether cell bodies or terminals are affected; (iv) the post-operative housing conditions; and (v) the onset and duration of peptide administration. Two possible explanations of peptide efficacy on functional recovery are considered: first, the peptide may accelerate spontaneously occurring recovery processes and second, the peptide may induce compensatory mechanisms underlying functional recovery without recuperation of the damaged neurons. These compensatory mechanisms seem to rely mainly on enhanced non-selective attention by activation of limbic structures. It is as yet unknown to which receptor system ORG 2766 binds; the analog lacks affinity for the known melanocortin (MC) receptors in brain, yet ORG 2766 is able to modulate the activity of endogenous opioids and the NMDA-receptor. A modulating influence of the peptide on NMDA-receptor activity might indirectly account for both enhanced attention--with ensuing behavioural recovery--and the acceleration of spontaneous recovery.

An ACTH/MSH(4-9) analog counteracts the behavioral effects of a mineralocorticoid receptor antagonist

The ACTH/MSH(4-9) analog Org2766 has been demonstrated to counteract age-related behavioral and morphological parameters especially those related to hippocampal functioning. Hippocampal mineralocorticoid receptors (MRs) are known to decline in the senescent rat. This decrease can be also counteracted by a chronic treatment with an ACTH(4-9) analog. The apparent effect of the peptide on hippocampal functioning prompted us to study a possible interaction between ACTH and MRs at a behavioral level. A chronic treatment with the ACTH(4-9) analog prevented the behavioral alteration induced by a specific MR antagonist (RU28318; 100 ng/microliters, ICV) in the Morris water maze and a step-through avoidance task. A possible role for neuronal excitation, involving MR activation, in peptide-facilitated behavioral recovery as seen in lesion studies and aging is discussed.

Effects of the ACTH4-9 analog Org2766 on brain plasticity: modulation of excitatory neurotransmission?

ACTH-like neuropeptides have been investigated in various paradigms such as cognition, neuronal damage and neuronal excitation. All their effects may be collectively described as modulation of neural plasticity. However, the mechanism of action accounting for these effects remains to be demonstrated. This report is an overview of the data and has incorporated some additional findings of the influence of the ACTH4-9 analog, Org2766, on neuronal excitation, especially in the hippocampus. An interaction with NMDA receptors may account for the various aspects of plasticity. Based on recent findings demonstrating that the ACTH4-9 analog counteracts both the NMDA antagonist, AP5, and NMDA-induced explosive running behavior, the hypothesis is put forward that glutamatergic neurotransmission is involved in behavioral changes induced by the ACTH4-9 analog.