Oxytocin and Effects on Sensory Function

The primary goal of this protocol is to model change in oxytocin concentrations in plasma after intravenous (IV) administration. Additional measurements will be performed on sensory function that could be influenced by oxytocin during later time periods when blood samples are widely separated by time. This protocol will describe the pharmacokinetics (PK) of intravenous oxytocin in healthy adult men and adult,non-pregnant women. PK samples will be obtained after an injection of intravenous oxytocin 10 IU over 60 seconds. Blood will be drawn for the PK samples prior to the oxytocin administration and then 11 times after administration. There are two additional measures which will assess two different aspects of sensory function. MEASURE 1: Light Touch Frequency Threshold In order to determine the highest frequency that specific nerve fibers can respond to, a simple device that produces an oscillatory / vibratory stimulus will be used on the hand. The subject places fingertips, palm, and palm side of the wrist sequentially and the device is set to slowly decrease the frequency of vibration from 1 kHz until the subject first perceives this. This is repeated three times at each site and takes less than 5 minutes in total. This will be performed before the oxytocin administration and 6 times after the administration of IV Oxytocin. MEASURE 2: Sustained Heat The surface of the skin of the forearm or leg is heated to 113A?F using a computer controlled thermode for a period of 5 minutes. This will be done before the IV Oxytocin and 4 times after the administration. A set of random thermal temperatures (98A?F-122A?F) will also be applied to the skin of the leg or forearm before the IV Oxytocin administration and 4 times after administration of IV Oxytocin.