Naval Special Warfare (NSW) operators are exposed to a variety of extreme environmental conditions and intense physical demands. In addition to breathing high pressure gases at depth, prolonged cold water immersion and inadequate recovery from sustained physical exertion negatively impact individual and team performance. Biotechnologies that could mitigate the effects of cold as well as support physical recovery represent a significant unmet need for the NSW operational community.

Oxytocin (OT) has a wide range of actions both locally in the brain and peripherally in the body including skeletal muscle. These peripheral effects can be mediated by classic ligand-receptor activation given the abundant expression of the oxytocin receptor in peripheral tissues, along with local expression of OT in peripheral tissues where it is likely to act in an autocrine manner. Exogenous OT via intranasal administration is FDA Investigational New Drug (IND)-approved and has been demonstrated as an easy and safe method to increase circulating OT concentrations that may augment actions on peripheral tissues.

Naval Special Warfare (NSW) operators are exposed to a variety of extreme environmental conditions and intense physical demands. In addition to breathing high pressure gases at depth, prolonged cold water immersion and inadequate recovery from sustained physical exertion negatively impact individual and team performance. Biotechnologies that could mitigate the effects of cold as well as support physical recovery represent a significant unmet need for the NSW operational community.

Oxytocin (OT) has a wide range of actions both locally in the brain and peripherally in the body including skeletal muscle. These peripheral effects can be mediated by classic ligand-receptor activation given the abundant expression of the oxytocin receptor in peripheral tissues, along with local expression of OT in peripheral tissues where it is likely to act in an autocrine manner. Exogenous OT via intranasal administration is FDA Investigational New Drug (IND)-approved and has been demonstrated as an easy and safe method to increase circulating OT concentrations that may augment actions on peripheral tissues.

Cold water operators undergo an extensive and unique set of physical, physiological, and psychological stressors during a mission. In-water transit may exceed 6 hours submerged in cold water, on rebreathers, and in a confined space. During this lengthy transit, operators must maintain vigilance over navigation, vehicle, and life support controls while exposed to the risks of mixed gas or oxygen rebreather diving, alongside hypothermia, dehydration, undernutrition, and other factors that can significantly degrade operator performance. Once the team has reached target, they must be at peak cognitive and physical readiness as they carry out their mission objective. When the mission objective is complete, the operators undertake the lengthy return trip back to their deployed base. Optimized operator cognitive and physical performance is essential throughout all phases of a cold water mission, and safe and tolerable approach to optimizing warfighter performance and resilience will be key for future cold water operations.

Given the potential thermogenic and recovery effects or intranasal OT, we hypothesize that prophylactic OT administration, compared to placebo, will mitigate deficits in mission-relevant performance during and after cold water exposure. For this project we will utilize the ONR Cold Water Performance Task Battery, which was designed based on results from a task analysis combined with input from the cold water operator community. The task battery has been validated for its ability to induce changes in core and peripheral body temperature, manual dexterity, cognitive performance, and physical performance following cold water exposure. Our hypothesis will be tested via one specific aim enrolling N=24 18-39 y/o men by using a rigorous, double-blind, placebo- controlled, within-subjects randomized cross-over trial comparing 48 IU OT vs placebo (saline) in cold water performance and recovery.

Specific Aim 1. To investigate the impact of intranasal OT on cold water task performance and recovery using the ONR Cold Water Performance Task Battery, which includes cold water exposure; cognitive performance testing via oculometric assessment and the Defense Automated Neurobehavioral Assessment (DANA); and physical performance testing via a simulated ruck, ladder climb, and manual dexterity testing.

Inclusion Criteria:

• Recreationally skilled swimmers

Exclusion Criteria:

• Smoking/vaping, a history of psychiatric disorders, safety requirements related to the oxytocin administration [hypersensitivity to oxytocin or vasopressin, history of hyponatremia, syndrome of inappropriate antidiuretic hormone secretion, or psychogenic polydipsia, on vasoconstrictors such as desmopressin, pseudoephedrine, or antidiuretic medication, or anti-inflammatory drugs, or muscle relaxants, low sodium and high osmolality levels, excessive smoking, excessive drinking, and significant nasal pathology.](streamdown:incomplete-link)

All will remain blinded until completion of human subjects data collection except the research pharmacist providing intranasal oxytocin or placebo.