Vasopressin opposes locomotor stimulation by ethanol, cocaine and amphetamine in mice

Vasopressin in the lateral septum decreases conditioned place preference to amphetamine and nucleus accumbens dopamine release

The lateral septum (LS) is a limbic nucleus interconnected with several brain areas involved in the regulation of mood and reward. Vasopressin (AVP) is a neuropeptide that has been related to the effects of drugs of abuse, but its role in the addictive process is poorly understood. LS expresses a high density of AVP 1A receptors (V_1A ). The aim of this work was to examine whether the modulation of LS AVP system affects the behavioral and neurochemical responses to amphetamine (AMPH) in male rats. Our results show that AMPH-induced conditioned place preference (CPP) produces a decrease in LS AVP content. Besides, we demonstrate that the microinjection of AVP in the LS impairs the expression of AMPH-induced CPP and that this effect is mediated by the activation of the V_1A receptor in the LS. AVP microinjection in the LS elicited a decrease in neuronal activity in the nucleus accumbens (NAc) in animals subjected to AMPH conditioning. Finally, AVP microinjection in the LS decreased dopamine (DA) release in the NAc. Overall, our data demonstrate that intra-LS AVP diminishes the expression of AMPH conditioning behavior while decreasing neuronal activity and DA release in the NAc. Presumably, the effects of AVP in the LS produce an inhibition of GABAergic projections to the VTA, increasing local inhibitory tone in this nucleus, which in turn reduces the activity of DA projections to NAc. Thus, these results contribute to the knowledge about the role of AVP in LS in regulating the reward circuit and addictive like behaviors.

Interplay Between Amphetamine and Activity Level in Gene Networks of the Mouse Striatum

The psychostimulant amphetamine can be prescribed to ameliorate the symptoms of narcolepsy, attention-deficit hyperactivity disorder and to facilitate weight loss. This stimulant can also have negative effects including toxicity and addiction risk. The impact of amphetamine on gene networks is partially understood and this study addresses this gap in consideration of the physical activity. The striata of mice exposed to either amphetamine or saline treatment were compared in a mouse line selected for home cage physical overactivity, a phenotype that can be mitigated with amphetamine, and in a contemporary control line using RNA-seq. Genes presenting opposite expression patterns between treatments across lines included a pseudogene of coiled-coil-helix-coiled-coil-helix domain containing 2 gene (Chchd2), ribonuclease P RNA component H1 (Rpph1), short stature homeobox 2 (Shox2), transient receptor potential melastatin 6 (Trpm6), and tumor necrosis factor receptor superfamily, member 9 (Tnfrsf9). Genes presenting consistent treatment patterns across lines, albeit at different levels of significance included cholecystokinin (Cck), vasoactive intestinal polypeptide (Vip), arginine vasopressin (Avp), oxytocin/neurophysin (Oxt), thyrotropin releasing hormone (Trh), neurotensin (Nts), angiotensinogen (Agt), galanin (Gal), prolactin receptor (Prlr), and calcitonin receptor (Calcr). Potassium inwardly rectifying channel, subfamily J, member 6 (Kcnj6), and retinoic acid-related (RAR)-related orphan receptor alpha (Rora) were similarly differentially expressed between treatments across lines. Functional categories enriched among the genes presenting line-dependent amphetamine effect included genes coding for neuropeptides and associated with memory and neuroplasticity and synaptic signaling, energy, and redox processes. A line-dependent association between amphetamine exposure and the synaptic signaling genes neurogranin (Nrgn) and synaptic membrane exocytosis 1(Rims1) was highlighted in the gene networks. Our findings advance the understanding of molecular players and networks affected by amphetamine in support of the development of activity-targeted therapies that may capitalize on the benefits of this psychostimulant.

Effects of alcohol and psychostimulants on the vasopressin system: behavioral implications

Drug addiction is a chronic brain disease characterized by a compulsion to seek drugs, a loss of control with respect to drug consumption, and negative emotional states, including increased anxiety and irritability during withdrawal. Central vasopressin (AVP) and its receptors are involved in controlling social behavior, anxiety and reward, all of which are altered by drugs of abuse. Hypothalamic AVP neurons influence the stress response by modulating the hypothalamic-pituitary-adrenal (HPA) axis. The extrahypothalamic AVP system, however, is commonly associated with social recognition, motivational and anxiety responses. The specific relationship between AVP and drugs of abuse has been rarely reviewed. Here, we provide an overview of the interaction between the brain AVP system and psychostimulants and alcohol. We focus on the effects of alcohol and psychostimulants on AVP regulation of the HPA axis, their effect on the brain AVP system and their behavioral implications, the influence of the AVP system on addictive behaviors, AVP's organizational effects on the brain and consequently on behavior, and we highlight clinical studies on the relation between the AVP system and drug addiction. Finally, we discuss the data to address areas that need further research to support clinical trials and prevent drug-related disorders. This article is protected by copyright. All rights reserved.

Effects of cocaine on maternal behavior and neurochemistry

Drug addiction is a chronic relapsing disorder that involves drug seeking and abuse despite the negative social and health consequences. While the potential effects of cocaine on child development have been extensively studied over the last 30 years, few researchers have focused on the effects of cocaine on maternal behavior, which includes offspring care and maternal aggression towards an unfamiliar individual. In humans, maternal cocaine use can lead to child neglect, abuse, and disrupt the mother-child bond. While it has been argued the developmental effects of maternal cocaine use on children were initially overstated, it is clear that disruptions of typical maternal behavior (i.e. postpartum depression, anxiety disorders) are detrimental to the physical and emotional health of offspring. Cocaine use in mothers is commonly associated with psychological disorders, including depression and anxiety, and it is postulated that many of the negative effects of maternal cocaine use on offspring are mediated through changes in maternal behavior. This review will summarize research on cocaine and maternal behavior in animal and human studies, discuss potential mechanisms, and suggest therapeutic strategies for treating cocaine-affected maternal behavior which may improve the physical and behavioral health of both mother and child. The primary objective is to stimulate future communication, cooperation, and collaboration between researchers who use animals and humans to study cocaine and maternal behavior.

Arginine vasopressin gene expression changes within the nucleus accumbens during environment elicited cocaine-conditioned response in rats

It is known that changes in gene expression within the nucleus accumbens (NAc) occur during cocaine dependence development. However, identification of specific genes involved in cocaine conditioning awaits further investigation. We conducted a high throughput gene expression profile analysis of the NAc, during different stages of the environment-elicited cocaine conditioning. Rats were assigned to two different environmental conditions. Cocaine conditioned group received a cocaine injection (10mg/kg, i.p.) prior to being placed in the activity chambers. Control rats received saline injections before being exposed to their environment. Both groups received a saline injection in their home cage. Conditioning training lasted for 10 days. Animals were then re-exposed to their previously paired environments only on day 12 (test session). We found that the gene for arginine vasopressin (AVP) was differentially expressed on experimental subjects during all stages of environment-elicited cocaine conditioning. To further validate our molecular results, biochemical and immunolocalization experiments were conducted. We found the presence of AVP within accumbal fibers and changes in AVP protein levels following cocaine conditioning. Moreover, we tested the effects of accumbal microinfusions of either AVP receptor V(1A) agonist [pGlu(4), Cyt6, Arg(8)] AVP 4-9 1.0 ng/0.5 microl, or V(1A) antagonist (CH2) 5[Tyr (Me) 2] AVP, 1.0 ng/0.5 microl or vehicle solution (0.9% saline solution) during different stages of the cocaine conditioning. Blockade of V(1A) receptors within the NAc during acquisition interrupted the expression of the conditioned response, while activation leads to an increase in this response. Our findings propose a new role for AVP in cocaine addiction.

Dexamethasone induces different wheel running activity than corticosterone through vasopressin release from the suprachiasmatic nucleus

During the analysis of wheel running activity, we found that corticosterone (1 mg/100 g BW) injection decreased wheel activity, while dexamethasone (0.1 mg/100 g) increased the activity. To clarify the functional differences between corticosterone and dexamethasone, we measured Arg-vasopressin (AVP) release from the suprachiasmatic nucleus (SCN) slice culture in vitro and AVP coding mRNA in the SCN in vivo. The corticosterone (0.2 and 2 microg/ml, final concentration in medium) decreased the AVP release, while it increased by dexamethasone (0.2 and 2 microg/ml). An AVP mRNA in the SCN was decreased by both corticosterone (1 mg/100 g) and dexamethasone (0.1 mg/100 g). The differences in wheel activity by corticosterone and dexamethasone are discussed from the changes of AVP in the SCN.

Diet salinity and vasopressin as reproduction modulators in the desert-dwelling golden spiny mouse (Acomys russatus)

The time for reproduction in mammals largely depends on the availability of water and food in their habitat. Therefore, in regions where rains are limited to definite seasons of the year, mammals presumably will restrict their breeding correspondingly. But while mammals living in predictable ecosystems would benefit by timing their season to an ultimate predictable cue, such as photoperiod, in unpredictable ecosystems (e.g., deserts) they will need to use a more proximate signal. We suggest a mechanism by which water shortage (low water content in plants) could act as a proximate cue for ending the reproductive season. The golden spiny mouse (Acomys russatus), a diurnal rodent living in extreme deserts, may face an increased dietary salt content as the summer progresses and the vegetation becomes dry. Under laboratory conditions, increased diet salinity lead to reproductive hiatus in females, notable in imperforated vagina, and a significant decrease in the ovaries, uteri, and body masses. In females treated with vasopressin (VP), a hormone expressed during water stress, the uteri and body masses have decreased significantly, and the ovaries exhibited an increased number of atretic follicles. VP has also led to a significant decrease in relative medullary thickness (RMT) of the kidney. It is thus suggested that VP could act as a modulator linking the reproductive system with water economy in desert rodents, possibly through its act on the energetic pathways.

Social stress does not alter the expression of sensitization to cocaine

The effects of chronic social stress on behavioral sensitization to cocaine were investigated in the Syrian hamster. Adolescent animals received either 15 mg/kg i.p. of cocaine or saline twice per day for 7 consecutive days. Two weeks following the last injection (young adulthood), they were given a challenge dose of 5 mg/kg i.p. of cocaine and scored for locomotion. Motor activity was significantly greater in cocaine-treated animals, demonstrating sensitization to this psychostimulant. Following the results of the first study, another group of adolescent animals was exposed to either a novel clean cage (control) or an aggressive resident male hamster (social stress) for 15 min following an injection of cocaine (20 mg/kg i.p. once daily) or saline for 7 consecutive days. The groups were as follows: Social Stress/Cocaine (SSC), No Social Stress/Cocaine (NSSC), Social Stress/Saline (SSS) and No Social Stress/Saline (NSSS). Two weeks following the last injection (Day 21), all animals were given a challenge dose of cocaine (5 mg/kg i.p.) and were rescored for locomotion. At that time, the suppressive effect of stress on locomotion was no longer detectable, as the expression of sensitization was observed in the NSSC but not in the SSC group. These results suggest that chronic social stress administered during adolescence does not cross-sensitize with cocaine in young adult hamsters.