ACTH 4-10 in the amelioration of neuropsychological symptomatology associated with senile organic brain syndrome

Neuroendocrine responses to intravenous infusion of arecoline in patients with Alzheimer's disease

We have reported that arecoline, a muscarinic receptor agonist replicably enhanced verbal memory in five of nine subjects with Alzheimer's disease (AD). To investigate the mechanism of cognitive improvement, circulating hormone measurements were made during high-dose acute and low-dose chronic intravenous (i.v.) arecoline administration to AD patients. Acute hormone responses were measured during, and for 6 h after, infusion of arecoline 5 mg i.v. over 30 min. Chronic responses were measured in cognitive responders during continuous i.v. infusion of arecoline escalating over 2 weeks (0.5-40 mg/day) and then during a 1 week infusion of the dose optimizing cognition (4-16 mg/day). Acute arecoline administered to 14 subjects produced unpleasant side-effects (e.g. nausea, vomiting), mean adrenocorticotrophic hormone (p = .0006), cortisol (p = .0001) and beta-endorphin (p = .0001) levels were elevated. During chronic arecoline treatment, no side-effects occurred and plasma cortisol, adrenocorticotrophic hormone and beta-endorphin levels were unchanged in nine subjects overall and in five cognitive responders. Thus, high-dose arecoline activates the hypothalamic-pituitary-adrenal (HPA) axis and may increase other anterior pituitary hormone levels, likely representing a 'stress response', but cognition-enhancing, low doses of arecoline do not produce a glucocorticoid response. Hence, arecoline-induced memory improvement is not due to the induction of 'stress' nor to the elevation of peripheral corticosteroid levels.

Advances in the pharmacotherapy of Alzheimer's disease

The authors reviewed the literature on the agents proposed for the treatment of Alzheimer's disease (AD). Different classes of drugs have been tested for this indication including psychostimulants, anticoagulants, vasodilators, hyperbaric oxygen, hormones, nootropics, cholinomimetics, monoaminergics and neuropeptides without conclusive evidence of being beneficial for the treatment of this condition. Among the cholinomimetics recent research data seems to indicate that they might produce modest benefits in mild-to-moderate AD patients. Recently, other drugs have also been proposed including neurotrophic factors, phosphatidylserine, angiotension [corrected] converting enzyme (ACE) inhibitors, calcium channel blockers, acetyl-L-carnitine, xanthine derivatives, anti-inflammatory agents, aluminum chelate agents, and D-cycloserine. Of these new strategies few hold promise of more substantial benefits for AD, with the possibility of altering the course of the disease, but these drugs await confirmatory trials.

Increased central immunoreactive beta-endorphin content in patients with Wernicke-Korsakoff syndrome and in alcoholics

beta-endorphin, adrenocorticotrophin, and alpha-melanocyte stimulating hormone were measured by radioimmunoassay in three areas of human brain at necropsy in seven subjects with Wernicke-Korsakoff syndrome and in 52 controls. Thiamin concentration in six brain areas was also measured. Mamillary body beta-endorphin concentrations were significantly increased in those with the syndrome compared with controls, and those controls with high alcohol intake showed increased mamillary body beta-endorphin compared with controls with low alcohol intake. Brain thiamin concentration was similar in both groups, with the exception of the brainstem, where it was reduced in subjects with Wernicke-Korsakoff syndrome. Thalamic beta-endorphin in controls was inversely correlated with thiamin in frontal white matter, frontal cortex, parietal white matter and parietal cortex, while beta-endorphin in the hypothalamus of patients was inversely correlated with thiamin in frontal cortex, parietal white matter, thalamus and brainstem. These results suggest that there is a disturbance of the endorphinergic system in Wernicke-Korsakoff syndrome which may be related to alcohol intake.

Interactions of anxiolytic and antidepressant drugs with hormones of the hypothalamic-pituitary-adrenal axis

Changes in hormones of the hypothalamic-pituitary-adrenal (HPA) axis in patients suffering from anxiety and depressive disorders are reviewed, and the changes that occur when animals are exposed to test situations used preclinically to model anxiety or depression. The effects of exogenous administration of HPA hormones both clinically and in animal tests is discussed and the effects of clinically used anxiolytics and antidepressants on hormones of the HPA axis. The final section discusses stress-induced changes in the CNS.

Influences of peripheral adrenocorticotropin 1-39 (ACTH) and human corticotropin releasing hormone (h-CRH) on human auditory evoked potentials (AEP)

Hormones of the hypothalamus-pituitary-adrenal (HPA) axis have been considered to form part of an efferent humoral system modulating central nervous stimulus processing. The present experiments were designed to compare the effects of iv bolus administrations of placebo, porcine ACTH 1-39 (1.5 U) and h-CRH (25 micrograms) on auditory evoked potentials (AEPs) in healthy men. Also, cardiovascular parameters, cortisol and self-reported mood were assessed. ACTH significantly reduced the amplitude of the N1 component of the AEP; P1 and P2 remained unchanged. The selective reduction of N1 amplitude defies an interpretation of the changes in terms of a reduced stimulus-induced cortical arousal following ACTH; the ACTH-induced changes may rather indicate an influence on frontocortical functions of directing attention. The effect of ACTH on N1 cannot be attributed to its adrenocorticotropic action or to cardiovascular changes, but appears to represent an intrinsic extraadrenal influence of the hormone. The data do not provide evidence for effects of h-CRH on central nervous stimulus processing in humans, after peripheral administration.

Neonatal exposure to a high level of ACTH4-10 impairs adult learning performance

Male offspring of Sprague-Dawley dams were injected with 25 micrograms of ACTH4-10 or the vehicle on days 2 through 7 postpartum. Peptide treated animals exhibited a marked motor response to the peptide injection. Adrenal weights of these animals were consistently heavier than littermate controls in both the developing and adult animals. ACTH4-10 treated neonates exhibited significantly poorer learning performance in the shuttle box and were slower to acquire the reversal learning problem of a visual discrimination task under light shock levels. In addition, these animals also exhibited an exaggerated startle response and a stronger thigmotaxis response in the open field than controls. These results indicate that exposing the developing nervous system to relatively high levels of ACTH4-10 can produce marked long-term effects on behavior.

The effect of MSH/ACTH 4-10 on delayed response performance and post-test locomotor activity in rats

Delayed response performance was measured in male, Long-Evans rats 1 hr after IP administration of various doses of MSH/ACTH 4-10 or control in a Hunter delayed reaction apparatus. Additional treatments consisting of naloxone 500 micrograms/kg (IP) and naloxone 500 micrograms/kg in conjunction with MSH/ACTH 4-10 95 micrograms/kg were also administered. Directly after delayed response performance was assessed, gross locomotor activity was determined. MSH/ACTH 4-10, at a dose of 95 micrograms/kg, significantly enhanced retention of a visual stimulus, while MSH/ACTH 4-10, at doses of 195 and 285 micrograms/kg, significantly impaired delayed response performance. Naloxone treatment resulted in significantly impaired delayed response performance when compared to control. However, naloxone plus MSH/ACTH 4-10 treatment failed to produce a significant difference from control in the delayed response performance paradigm. In post-test locomotor activity determination, an apparent dose-response existed for MSH/ACTH 4-10 with the two highest doses (190 and 285 micrograms/kg) resulting in significantly increased locomotor activity. The observed delayed response performance data support theories implicating MSH/ACTH peptides in attentional processes involving visual stimuli. The fact that large doses of MSH/ACTH 4-10 disrupt delayed response performance while increasing post-test activity suggest that an optimum level of effect caused by the MSH/ACTH peptide exists in this paradigm.

Melanocortins, neural plasticity and aging

Peptides derived from ACHT and alpha-MSH are known to exert trophic influences on peripheral and central nervous structures. Age-related brain diseases may in part be related to loss of neural plasticity. Melanocortins improve adaptional abilities of the nervous system. Chronic treatment with melanocortins may counteract age-related brain pathology.

Effects of ACTH and prednisone on mood: incidence and time of onset

Prior studies of mood and cognitive changes produced by ACTH and glucocorticoids have not characterized accurately the incidence or time of onset of these changes. In this study mood and cognitive reactions of fifteen medical patients treated with ACTH or prednisone were studied prospectively. ACTH produced a lessening of dysphoria by the third treatment day, and mild euphoric reactions occurred in three of seven of the patients treated. Prednisone produced a reduction of dysphoria by the seventh day, but no euphoric reactions in the eight patients treated with it. Neither medical symptom improvement nor elevation of plasma cortisol levels in the patients given ACTH appeared to account for the results. The mechanism of the observed mood change remains to be elucidated.

Dishabituating effects of an ACTH 4-9 analog in a vigilance task

Ten male adults were tested in a vigilance task after oral administration of either 40 mg ACTH 4-9 analog, ORG 2766, or placebo in a single three hour session. EEG spectra, averaged auditory evoked responses, heart rate and blood pressure, and behavioral performance were measured during a vigilance task. ACTH 4-9 analog treatment led to a decreased inhibition of the central nervous system across the experiment: to less mean power density and faster center frequencies within the alpha band, and to less attenuated amplitudes of the components of the auditory vertex potential (P50, N100, P200). Treatment effects increased towards the end of the session and might indicate a dishabituating effect, probably due to suppression of inhibitory influences of limbic structures on mesencephalic reticular activity.

Pharmacotherapy of memory loss in the geriatric patient

Memory loss is a common problem with advancing age and a prominent symptom in dementia. Categories of drugs used to reverse memory loss and enhance recall are reviewed. Positive results have been observed with cholinergic drugs, acetylcholine precursors, and the newer category of cerebral metabolic enhancers and nootropic agents. Combinations of these classes of drugs are being tried in current research.

ACTH 1-17 and short-term memory, anxiety, heart rate, blood pressure

The research investigated the effects of acute ACTH 1-17 administration on plasma cortisol, short-term memory, anxiety state, blood pressure and heart rate. In a double blind crossover design, healthy volunteers were serially evaluated at 5 min, 20 min, 40 min, 60 min after injection of ACTH 1-17 or placebo in separate sessions. Results show that ACTH 1-17 produced, in addition to an increase in plasma cortisol (5 min - 60 min), significant improvements in short-term memory (5 min), a reduction in anxiety (20 min and 40 min), and an increase in systolic (5 min and 20 min) and diastolic blood pressure (5 min). If confirmed by other studies, the short-term memory effect of ACTH 1-17 at 5 min after i.v. could suggest a central action of the peptide, and confirm the role of HPA axis as a modulator of performance and emotional arousal during acute environmental changes.

Studies on the possible central effects in man of a neuropeptide (ACTH 4-9 analogue)

The central effects of a neuropeptide, ACTH 4-9 analogue (Organon 2766), were studied in man using digit symbol substitution (DSS), symbol copying, digit span, electroencephalography and auditory evoked potentials, critical flicker fusion (CFF) and pupillary response to light. Performance was measured overnight, and each of 6 subjects ingested 300 mg caffeine, 40 mg ACTH 4-9 analogue and matching placebo. With placebo there was a marked deterioration in performance overnight. The number of substitutions on DSS and the numbers of symbols copied fell, and the threshold for CFF and number of errors on the vigilance task increased. These effects were not seen after ingestion of caffeine (300 mg), though caffeine may have led to some deterioration in the ability to remember digits. The neuropeptide did not attenuate the decrements in performance overnight.

Endocrine influence on disease outcome: experimental findings and implications

The psychosocial environment may impose stressor effects on animal and man. Adaptation to these environmental changes requires behavioural, autonomic, neuroendocrine, metabolic, etc. processes. The neuroendocrine system plays a key role in the integration of these processes. Experimental evidence obtained in the rat suggests that neuropeptides related to ACTH, endogenous opioids and their fragments, vasopressin, etc., but also oestrogens may selectively influence the form and magnitude of acute cardiac response to emotional stressors. Dichotomies between the behavioural and cardiac responses may occur too. It is suggested that neuroendocrine action on brain mechanisms that are involved in the organization of behavioural and bodily responses to stressors are important in physiological adaptation. Neuroendocrine disturbances (two much or too little neuropeptides and other hormones) may thereby contribute to the outcome of psychosomatic diseases.

Distractability under the influence of an ACTH 4-9 derivative

Event-related brain potentials, autonomic responses, and response latency under distraction conditions served to investigate the effects of an ACTH 4-9 derivative (ORG 2766) on attention. Male volunteers (45) received either 40 mg ORG 2766 or placebo in a double-blind setting. Two-stimulus trials with acoustic warning signal (S1) and acoustic S2 which had to be interrupted by immediate button press, preceded trials with distraction during the warning interval in 50% of the trials. A final period without distraction served to test for rebound effects. A reduction in early CNV was found in placebo subjects under distraction, while subjects under ORG 2766 showed no reduced early negativity, but increased late negativity under this condition. Peptide subjects differed from controls in evoked potential components, showing enhanced N1 and P3 amplitudes. Activity in the alpha band was elevated. Postexperimental systolic blood pressure was raised by 15 mm Hg under ORG 2766. Results are in agreement with previous findings and suggest ORG 2766 effects on distraction resistance and attention fixation.

Neuropeptides, mental performance and aging

The presence of peptidergic neuronal networks in the brain and the modulating action of neuropeptides on brain functions as evidenced by their behavioral influence in particular support the concept that the brain like the peripheral endocrine glands is an endocrine target organ which is as sensitive to treatment with neuropeptides as the peripheral glands are to pituitary hormones. Animal and human data are reviewed showing that neuropeptides related to ACTH/MSH affect motivational and attentional processes and that those related to vasopressin are involved in memory processes. Since these functions decline during aging it is postulated that a decreased bioavailability of neuropeptides in brain of elderly people is associated with specific disturbances in mental performance. Thus, the decreased mental ability of the aged may be restored by treatment with neuropeptides particularly those with little, if any, peripheral, endocrine activity, like the ACTH neuropeptide Org 2766 and the vasopressin neuropeptide DGAVP.

Central nervous system and peripheral effects of ACTH, MSH, and related neuropeptides

Adrenocorticotropic Hormone (ACTH), Melanocyte-Stimulating Hormone (MSH), and related peptides have been shown to have several neurogenic effects: alteration of cerebral protein synthesis, RNA synthesis, protein phosphorylation, and neurotransmitter turnover. Furthermore, there appears to be an ACTH containing circuit in the CNS which originates in the arcuate nucleus. Changes in concentration of the peptides in this family have been shown to alter electrophysiology, neuromuscular function, and behavior (e.g., grooming, learning) in infrahuman subjects. These findings suggest that the neuropeptides MSH and ACTH influence the capacity of an organism to efficiently evaluate information and influence the affective functioning of humans.

Intraventricular ACTH reduces social interaction in male rats

Intraventricular ACTH (1.25 microgram), ACTH (1.6 microgram) and ACTH:D-Phe (1.6 microgram) resulted in significant reductions in the time that pairs of male rats spent in active social interaction. This decrease in social behaviour was not accompanied by a decrease in motor activity. The results are similar to those previously found with peripheral administration of ACTH and suggest that these behavioural effects of ACTH are centrally mediated. None of the ACTH fragments had a significant effect on the latency with which thirsty rats started drinking in an unfamiliar environment. The results are discussed in relation to a possible anxiogenic action of ACTH.