Vasopressin and memory: improvement in normal short-term recall and reduction of alcohol-induced amnesia

Potential clinical applications of current and future oral forms of desmopressin (Review)

Desmopressin is a synthetic analogue of vasopressin and a selective vasopressin receptor 2 agonist. It was first synthesised in 1967 and utilised for its antidiuretic properties. It is also used in bleeding disorders to enhance clotting. Other potential uses of the drug have been reported. The present review aims to provide a broad overview of the literature on potential further uses of oral forms of desmopressin. Key therapeutic areas of interest were identified based on known physiological activities/targets of desmopressin or reports of an effect of desmopressin in the literature. The feasibility of adequate dosing with oral forms of the drug was also considered. Systematic literature searches were carried out using the silvi.ai software for the identified areas, and summaries of available papers were included in tables and discussed. The results of the searches showed that desmopressin has been investigated for its efficacy in a number of areas, including bleeding control, renal colic, the central nervous system and oncology. Evidence suggests that oral desmopressin may have the potential to be of clinical benefit for renal colic and bleeding control in particular. However, further research is needed to clarify its effect in these areas, including randomised controlled studies and studies specifically of oral formulations (and doses). Further research may also yield findings for cancer, cognition and overactive bladder.

Oxytocin and vasopressin: Signalling, behavioural modulation and potential therapeutic effects

Oxytocin (OT) and vasopressin (AVP) are endogenous ligands for OT and AVP receptors in the brain and in the peripheral system. Several studies demonstrate that OT and AVP have opposite roles in modulating stress, anxiety and social behaviours. Interestingly, both peptides and their receptors exhibit high sequence homology which could account for the biased signalling interaction of the peptides with OT and AVP receptors. However, how and under which conditions this crosstalk occurs in vivo remains unclear. In this review we shed light on the complexity of the roles of OT and AVP, by focusing on their signalling and behavioural differences and exploring the crosstalk between the receptor systems. Moreover, we discuss the potential of OT and AVP receptors as therapeutic targets to treat human disorders, such as autism, schizophrenia and drug abuse.

Localization of vasopressin (V1a) receptor binding and mRNA in the rhesus monkey brain

Centrally released arginine vasopressin (AVP) has been associated with various behavioural and cognitive effects, such as scent marking, aggression, and memory, which are believed to be mediated by the V1a subtype of the vasopressin receptor. Although the distribution of V1a receptors is conserved in a few brain regions, the pattern of expression of this receptor is, in general, highly species-specific. We have used receptor autoradiography with the linear V1a receptor ligand (125I-Phenylacetyl-D-Tyr(Me)-Phe-Gln-Asn-Arg-Pro-Arg-Tyr-NH2) to characterize the pattern of receptor binding in the rhesus monkey brain. Brain sites of V1a receptor synthesis were defined using in-situ hybridization. The regions of highest V1a receptor density included the prefrontal, cingulate, pyriform, and entorhinal cortex, as well as the presubiculum and mamillary bodies. In addition, V1a receptor binding and mRNA were detected in several regions reported to have V1a receptor in most rodents, including the amygdala, bed nucleus of the stria terminalis, lateral septum, hypothalamus and the brainstem. The distribution is consistent with a role for vasopressin in higher cognitive functions, especially memory, in primates.

Neuropsychological effects of vasopressin in healthy humans

Animal research indicated that vasopressin (VP) exerts its principle behavioral influence, the improvement of memory formation, through an action on septo-hippocampal and connected limbic structures. Here human research is reviewed with the notion of a comparable effect of VP in healthy humans. Although the human studies yielded less consistent results than those in rats, they indicate that VP is able to improve declarative memory formation which is the type of memory essentially relying on hippocampal function. The effect appears to center on the encoding process for memory. In examinations of event-related brain potentials (ERPs) VP was consistently found to increase the 'mismatch negativity' (MMN) and the P3 components which are ERP potentials closely linked to the hippocampal processing of novel, unexpected and salient events. Enhanced processing of these stimulus aspects is considered to precipitate memory encoding. The regulation of voluntary selective attention and arousal do not appear to be primary targets of VP effects in humans. A mediation of effects by peripheral changes can be excluded since the central nervous effects were observed in studies using intranasal VP administration providing a direct access to brain functions.

Effects of meal composition on blood alcohol level, psychomotor performance and subjective state after ingestion of alcohol

Moderating effects of meal composition on psychomotor performance impairment and feelings after alcohol were examined in a between-subjects design. Fifty-one male volunteers fasted or received either a high carbohydrate (85% energy) or a high protein (94% energy) meal. Alcohol was administered at a dose to achieve a blood alcohol level (BAL) of 60 mg/100 ml, as a placebo. Subjects performed a dual task of primary tracking and secondary reaction time and a five-choice reaction time task. Feelings were also assessed by rating. The high carbohydrate meal reduced BAL at peak and 2 h after drinking, but a high protein meal had no significant effect. Although performance was impaired by alcohol, neither meal significantly reduced impairment and there was no effect of meal type on performance in the placebo condition. However, alcohol increased rated intoxication and the high carbohydrate meal reduced this effect. Subjects who had consumed high protein meals had more negative affect 2 h after alcohol than did subjects who had consumed high carbohydrate meals or fasted. It is concluded that there is only a weak relationship between BAL and performance impairment and food has only limited effects on impairment, although it reduces BAL.

Effect of acute and chronic treatment with desglycinamide-[Arg8]vasopressin in young male and female volunteers

A single dose of DGAVP (2 mg) and a chronic treatment of 2 weeks (1 mg/day) were given to male and female volunteers by the intranasal route. Memory, mood, vigilance, and attention were tested starting 60 min after treatment. Initial storage of abstract words was improved in the males but not in the females after chronic treatment with DGAVP. This effect persisted after discontinuation of treatment. Initial storage and learning of concrete words were not affected by treatment with DGAVP. Chronic, but not acute, treatment with DGAVP reduced the reaction time for scanning of digits in a memory comparison task (Sternberg paradigm) in both sexes. No treatment effects were found for visual memory, vigilance, attention, mood, or blood pressure. The present study indicates a sexual dimorphism in the effect of DGAVP on certain memory processes.

Effect of a single dose of des-glycinamide-[Arg8]vasopressin or oxytocin on cognitive processes in young healthy subjects

A single dose of des-glycinamide-[Arg8]vasopressin (DGAVP, 2 mg intranasal) or oxytocin (OXT, 20 IU intranasal) was given to female and male volunteers, respectively, in a placebo-controlled double-blind trial. Memory, vigilance, attention, and mood were tested starting 10 minutes after treatment. The DGAVP dose improved delayed recognition of abstract words when measured 1 week after treatment and reduced the intercept of a memory comparison task (Sternberg paradigm). A trend was present for DGAVP and OXT to affect learning, i.e., storage processes of verbal memory in an opposite way; DGAVP improved, while OXT attenuated initial storage and the rate of storage. No treatment effects on visual memory and vigilance were found. Of the mood measures, vigor was reduced immediately after treatment with OXT.

Vasopressin and cognitive processes: two event-related potential studies

Two experiments studied the influence of arginine-vasopressin (AVP) on cognitive processes by means of an electrophysiological measure, the late positive complex (LPC) of the event-related potential. The LPC varies systematically with cognitive processes. The classical oddball paradigm and an incidental memory task (structural encoding of emotional adjectives) were used. The two studies differed only in the dose of AVP (study 1: three time nasal application of 10 IU AVP; study 2: 20 IU). In study 1, AVP intake enhanced memory performance. The LPC elicited by oddball stimuli was not influenced by AVP, neither when compared before and after intake nor when compared to placebo treatment. However, specific influences of AVP on the LPC elicited during the structural encoding task were observed. In both studies, AVP intake resulted in a marked change of the scalp distribution of the P3 component, which is a prominent part of the LPC. Furthermore, subjects treated with the lower dose of AVP showed a more positive P3 component on emotional (negative and positive) adjectives, when compared to neutral ones. The results suggest that vasopressin influences the central nervous processing of the emotional content of stimuli.

Effects of vasopressin on the habituation of the orienting reaction in men

Effects of arginine-vasopressin (AVP) on the habituation of the orienting reaction and response to stimulus mismatch were investigated in a between-group design with 40 healthy male volunteers using skin conductance and heart rate responses as dependent measures. Twenty-one 1000 Hz tones of 90 dB(A) intensity and 2 s duration were presented with alternating intervals of 20 and 140 s. Stimulus mismatch responses were analyzed to the tones after the long intervals and to a change of the interval duration. The expected prevention of habituation as an indicator of a general stimulus-related increase of phasic arousal under AVP could not be confirmed. There were no differences between the AVP and the placebo group in the skin conductance and heart rate responses. The interval change did not provoke a dishabituation reaction, but responses to the tones after the long intervals were reliably enhanced. However, AVP did not increase the reaction to stimulus mismatch. It is concluded that autonomic indicators of the habituation of the OR remain unaffected by AVP.

Effects of DDAVP on movement planning and execution processes in the healthy elderly

Effects of DDAVP on speed and consistency of planning and executing simple and complex movements in healthy older adults were studied. A simple reaction time (SRT) task, a single-plane movement task, and two tasks involving multiplane movements of distal upper extremities were performed with and/or without a 0.6 ml intranasal dose (60 micrograms) of DDAVP or placebo. Results indicated that DDAVP had no significant effect on speed or consistency of SRT processes, or the speed with which simple or complex movements were planned or executed. There was also no effect on retention of motor responses.

Effects of DDAVP on gender-specific verbal and visuospatial tasks in healthy young adults

Although several studies have demonstrated the efficacy of the vasopressin analog DDAVP in enhancing human cognition, few previous studies have explored possible interactions of treatment with DDAVP and gender in healthy young adults. The present study was undertaken to explore the effects of treatment with DDAVP on gender-specific tasks. Male and female volunteers were treated with either DDAVP or saline and asked to recall lists of words and to perform the Paper Folding and Stroop Color Word Tests. Although treatment with DDAVP produced few effects in these tasks, the effects that were noted involved impairment of performance.

A placebo-controlled evaluation of vasopressin for ECT-induced memory impairment

Vasopressin may be involved in normal memory functions and may alleviate certain memory impairments. In this study, the usefulness of vasopressin to relieve electroconvulsive therapy (ECT)-induced memory impairment was evaluated using a placebo-controlled, random assignment, double-blind design. Patients were 33 depressives receiving bilateral ECT. Vasopressin, in a nasal spray, was administered q.i.d. from the first through the fifth ECT. Extensive memory testing evaluated both retrograde and anterograde amnesia; ratings of depression and patient ratings of subjective memory complaints were also obtained. Results did not show statistically significant evidence of benefit from vasopressin, though a number of comparisons were in the predicted direction. The role of vasopressin in reducing memory impairment of various types remains to be elucidated.

Vasopressin but not oxytocin enhances cortical arousal: an integrative hypothesis on behavioral effects of neurohypophyseal hormones

Behavioral changes after administration of the neurohypophyseal hormones vasopressin and oxytocin can be observed in animal and man. Several groups attempted to specify these changes in terms of memory or attention processing enhancement for vasopressin and amnesic properties for oxytocin. These interpretations, however, were targets for recent criticism. In a double-blind between-subject comparison with male volunteers receiving arginine-vasopressin (AVP), oxytocin or placebo intranasally prior to the experimental session, we tried to develop an alternative hypothesis on the basis of behavioral and EEG measures. At the beginning of the session subjects had to learn a list of 25 unrelated nouns within five trials. Recall was assessed 1 h later. Neither learning nor long-term recall were affected by peptide treatments. In a second vigilance task subjects had to covertly count eight series of tone pips. Averaged auditory evoked potentials to these tones showed the expected habituation during the course of the task within all three groups. Vasopressin-treated subjects, however, displayed significantly higher amplitudes of the vertex potential as compared to the other treatment groups. AVP effects were most prominent with the longest interstimulus interval. No influences on heart rate or blood pressure were found. Results indicate that vasopressin induces an enhancement of stimulus-related phasic cortical arousal, and that in this respect oxytocin has no effect.