Facilitation of Extinction Retention and Reconsolidation Blockade by IV Allopregnanolone in PTSD.

Background: Allo is a neurosteroid (hormone) produced from progesterone by the brain, adrenal glands, testes, and ovaries. Production of Allo and its equally potent, structurally similar stereoisomer pregnanolone (PA) is stimulated when certain neurons in the brain are activated and when stress activates the adrenal glands. Allo and PA markedly increase effects of gamma-amino-butyric acid (GABA; an inhibitory neurotransmitter) in the brain, thereby regulating arousal and responses to stress. Allo and PA also influence processes that strengthen or weaken memories. Basic research suggests that several factors can reduce production of Allo: exposure to chronic or extreme stress, prolonged social isolation, chronic intermittent heavy alcohol use, certain oral contraceptives, chronic use of some psychiatric medications or other substances used to manage PTSD such as nicotine, exposure to environment toxins, and genetic predisposition. Research shows that Allo and PA production is reduced in a large subpopulation of women and men with PTSD. Reduced Allo and PA is strongly associated with PTSD severity and poor retention of extinction learning, both of which contribute to chronic PTSD. The proposed study thus will be conducted in adult men and women with chronic PTSD. Women will be studied during two distinct phases of the menstrual cycle because progesterone levels (and therefore levels of Allo and PA) change markedly across the menstrual cycle, as do problems with extinction retention. Study Procedures: Eligible participants between 18 and 55 years of age will take part in a widely used, standardized 3-day laboratory psychophysiology paradigm during which activation of the sympathetic nervous system (fight/flight system) is monitored via small electrode patches placed on the skin. The paradigm involves startle testing on Days 1, 2 and 3. During startle testing, participants will hear sudden bursts of white noise through headphones, see colored shapes on a computer screen, and feel sudden (not painful) blasts of air to the neck. The electrodes record participants' eye blinks, skin conductance, and heart rate. The startling sounds will be about as loud as a train but last only a fraction of a second. Participants will sit quietly with their eyes open as they listen. On study Day 2, participants are randomized by "luck of the draw" or "chance" to receive either IV Allo or placebo. On study Days 2 and 3, a brief memory test also will be conducted. Blood is collected each day for measurement of Allo, PA and other neurobiological factors that may affect the potential beneficial effects of Allo. There will be a follow up phone session (about a week after the Day 3 visit/session). Before starting the above studies, the investigators will conduct pharmacokinetic (PK) studies in a small group of individuals with PTSD to confirm that the selected IV Allo doses increase blood Allo levels as expected. Implications: These studies may help us understand treatable factors that increase risk for chronic or treatment-resistant PTSD and PTSD-related depression. They may also tell us whether treatments that increase Allo might help prevent or treat PTSD. IV Allo (brexanolone) at much higher doses than used in this study) is currently FDA-approved for the treatment of postpartum depression, supporting the potential for this research to spur development of Allo as a new treatment for PTSD. Study Population: About 96 individuals with PTSD (between 18-55 years of age) will be recruited to participate in these studies. Half of the women will be studied during the follicular phase of the menstrual cycle (after onset of menses) and half during the luteal phase (after ovulation). The study is being conducted at Massachusetts General Hospital, Boston, MA.