Arginine vasopressin (AVP) has long been recognized for its roles in water retention and cardiovascular regulation [1-3], yet its influence within the central nervous system has only recently become clear. Expressed in the hypothalamic paraventricular and supraoptic nuclei [4], while acting through V1a and V1b receptors [5], AVP modulates synaptic signaling across the limbic system, hippocampus, and brainstem [6-8]. Over the past five years, innovations in in vivo imaging and viral-tracing techniques have mapped previously unknown AVP circuits and revealed anticipatory and context-dependent modes of secretion. This review organizes recent work into a multi-scale framework, namely synaptic, circuit, and translational, to capture how AVP shapes neural computations that underline social and emotional behaviors and how these mechanisms might be harnessed to treat neuropsychiatric disorders.

AVP signaling at the cellular level is primarily mediated by G-protein-coupled V1a and V1b receptors, activating phospholipase C, Ca²⁺ influx, and MAPK cascades [9-11]. In recent research, patch-clamp and imaging studies show that AVP modulates neuronal excitability through both pre- and postsynaptic mechanisms, reducing inhibitory GABA release in olfactory bulb circuits [12,13] while increasing excitatory drive and synaptic protein expression such as PSD95 and GluA1 in hippocampal and amygdala neurons [14]. These effects collectively enhance long-term potentiation and reconfigure local oscillatory activity, aligning AVP action with mechanisms of memory and stress adaptation [15]. Crosstalk with oxytocin receptors (OTRs) further refines AVP’s impact on cell signaling, suggesting coordinated control of social and homeostatic responses at the synaptic scale [16].

In another study by Kim et al. [17], they examined how vasopressin neurons exhibit anticipatory activation before physiological disturbances occur. Using fiber photometry, optogenetics, and calcium imaging, researchers discovered that AVP neurons respond to learned, feedforward signals from higher brain centers during behaviors like drinking or salt intake, ‘before’ osmotic changes happen. This represents a shift from viewing vasopressin as purely reactive to understanding it as a predictive, anticipatory system for maintaining homeostasis.

Table 1 summarizes the method and key findings in six of the selected recent studies on vasopressin signaling in synaptic level.

At the systems level, AVP neurons form widespread projections linking hypothalamic nuclei with limbic and midbrain structures including the lateral septum, amygdala, bed nucleus of the stria terminalis (BNST), and dorsal raphe [18,19]. In recent studies, circuit-specific studies combining fiber photometry and optogenetics have revealed that AVP activity anticipates osmotic or social challenges [17] and gates social investigation, aggression, and anxiety [20,21]. In the lateral septum, diminished AVP-evoked excitation produces social deficits in Shank3B⁺/^- mice, rescuable through chemogenetic stimulation, linking disrupted AVP modulation directly to autism-related phenotypes. Additionally, AVP enhances serotonergic activation in the dorsal raphe during social interactions [22], illustrating how neuromodulatory cross-system interactions regulate affect and affiliative behavior. Collectively, these findings show that AVP acts as a circuit-level tuner of social and emotional behavior, integrating internal state and environmental cues.

In another study by Francesconi et al. [23], the group examined not only vasopressin, but together with oxytocin, how they converge on the BNST to regulate anxiety-related behaviors. Both AVP and oxytocin excite specific BNST neuron types (I and III) primarily through OTRs rather than vasopressin receptors, with inputs from hypothalamic regions (suprachiasmatic and supraoptic nuclei). Chemogenetic silencing of OTR-expressing BNST neurons increased anxiety-like behavior in fear-potentiated startle tests and reduced open-arm exploration. This demonstrates the BNST as a critical integration point where neuropeptide systems balance external threat assessment with internal physiological needs, highlighting the anxiolytic (anxiety-reducing) role of OTR-BNST neurons in helping organisms overcome threat avoidance to meet survival needs.

Table 2 summarizes the method and key findings in four of the selected recent studies on vasopressin signaling in behavior level.

Recent advances have brought AVP research closer to clinical application. Novel positron emission tomography ligands for V1a receptors [24] allow non-invasive visualization of receptor density and drug occupancy in living subjects, while measurements of circulating AVP and copeptin provide accessible biomarkers of stress and brain-body integration. Dysregulated AVP signaling has been implicated in autism spectrum disorder and mood disorders, prompting interest in selective V1b antagonists and circuit-targeted neuromodulation [25-27]. Clinical data show sex differences in relative AVP correlation structure in neurocritical patients, specifically in postmenopausal female, plasma and cerebrospinal fluid AVP levels showed a moderate positive correlation, while cerebrospinal fluid AVP and serum sodium showed a negative correlation [28]. Although overall AVP levels do not vary by sex, this correlation suggests the physiological responsiveness of AVP secretion to sodium fluctuations may be distinct in postmenopausal females. Overall, combining chemogenetic circuit control with pharmacological precision could potentially yield next-generation therapies for social and emotional dysfunctions rooted in AVP network imbalance.

Table 3 summarizes the method and key findings in four of the selected recent studies on vasopressin signaling in clinical level.

Despite rapid progress, major questions remain: how does AVP encode the valence of social stimuli, and how do receptor subtypes cooperate across time and space? Integrating spatial transcriptomics, connectomics, and computational modeling will be essential to capture the dynamic logic of AVP signaling. Comparative studies across species, including primate and human data, are needed to validate translational relevance. The field is moving toward a unified view of AVP as both a homeostatic and cognitive neuromodulator, bridging physiological regulation with higher-order social cognition.

Across the past 5 years, vasopressin research has evolved from descriptive neuroendocrinology to multi-scale systems neuroscience. Evidence now shows that AVP coordinates activity from the synapse to the network to the organism, integrating social, emotional, and physiological domains. Understanding this hierarchy opens new therapeutic pathways and redefines vasopressin as a master regulator of adaptive brain states.