400 mg per day given in this study (compounded by Belmar Pharmacy in Colorado):
"We used a novel probe of emotion processing, modulation and regulation to assess the neural basis of allopregnanolone’s impact on emotion processing.
We demonstrate that elevation of allopregnanolone following pregnenolone administration is associated with reduced activity in regions linked to the generation of negative emotion, increased activity in regions linked to regulatory processes, and enhancement of functional connectivity; an effect that is associated with less self-reported anxiety. To our knowledge, this is the first neuroimaging study to demonstrate an effect of allopregnanolone on emotion regulation, a function likely dysregulated in anxiety disorders. These findings add to the current knowledge regarding the effects of allopregnanolone on emotion neurocircuits, and provide neuroimaging evidence that allopregnanolone may modulate neurocircuits in directions counter to those observed in anxiety psychopathology.
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regnenolone administration reduced activity in neural circuits associated with the generation of negative emotions. Across all conditions and all face types, pregnenolone administration decreased right amygdala and right insula activity, and serum levels of pregnenolone and allopregnanolone were negatively correlated with amygdala and insula activation levels. The amygdala is a key region in threat detection (52), fear conditioning (53), and emotional salience (54). The insula is responsible for interoception (55), disgust (56), emotion processing (57), emotional recall (36), and anticipation of aversive stimuli (58). Both regions are associated with negative emotional response (57), and greater amygdala activation in response to the presentation of facial expressions is associated with greater magnitude of emotional response (59–63). Additionally, activation reductions in amygdala and insula are associated with down-regulation of negative emotions (64). Thus, allopregnanolone’s reduction of activity in amygdala and insula suggests that allopregnanolone may reduce emotional reactivity to aversive stimuli.
Pregnenolone administration also increased activity in the dmPFC, a region linked to regulatory control over emotion. This finding was specific to the appraisal condition. We have previously demonstrated that shifting attention to become aware of and evaluate the intensity of one’s emotional response to aversive stimuli leads to robust activation of dmPFC and rostral ACC (59, 65–67). Behavioral studies of emotional appraisal and labeling report that this strategy lowers distress (68) and facilitates habituation (69). Thus, allopregnanolone’s enhancement of dmPFC activity during appraisal suggests that allopregnanolone may facilitate the evaluation of one’s own emotional response and aid in successful down-regulation of negative emotions. Interestingly, greater dmPFC activity during appraisal was associated with greater self-reported anxiety. As the dmPFC is central to conscious threat appraisal (70), greater dmPFC activity in individuals with higher self-reported anxiety could reflect greater levels of threat processing. Alternatively, higher activity in this region could reflect greater task engagement in certain individuals.
Finally, pregnenolone administration increased connectivity between amygdala and dmPFC during appraisal, with greater connectivity associated with reduced self-reported anxiety. Psychophysiological interaction (PPI) reflects the connectivity between one region and another during a particular context, controlling for the baseline relationship between regions. Thus, the current results suggest that allopregnanolone is associated with greater functional coupling between amygdala and dmPFC during appraisal specifically. However, PPI does not assess the impact of third-party regions on the two regions of interest, and does not reflect causal relationships. While these correlational findings do not necessarily provide evidence of an inhibitory or excitatory relationship, they may suggest potential neural mechanisms of emotional regulation given known structural connections and reciprocal feedback loops between amygdala and mPFC (71–73). Previous research indicates that emotion regulation depends on interactions between dmPFC and amygdala (74). At least one previous study has demonstrated that enhanced connectivity between dmPFC and amygdala is associated with successful emotion regulation and less negative affect (75). Of note, some evidence suggests that successful regulation is associated with an inverse relationship (anti-correlation) between dmPFC and amygdala (64, 76). However, in our sample, greater connectivity between amygdala and dmPFC was associated with less self-reported anxiety, suggesting allopregnanolone’s modulatory effects on connectivity may aid dmPFC-mediated appraisal and/or reduce amygdala-mediated negative emotional responding. Our findings extend those of Van Wingen and colleagues (34) by demonstrating that allopregnanolone’s selective enhancement of dmPFC to amygdala connectivity is associated with reduced anxiety. Since several anxiety disorders are characterized by a lack of neural regulatory control (77) and impaired emotion regulation (38), future studies should examine allopregnanolone’s potential as a neurosteroid target for pharmacologic intervention for these individuals.
Allopregnanolone likely impacts emotion regulation neurocircuitry through GABAergic mechanisms, though it may also impact this circuitry through its enhancement of neurogenesis (78) myelination (79) or neuroprotection (80–83). Amygdala and mPFC are rich in GABA(A) receptors (28) and endogenous allopregnanolone (48), suggesting that allopregnanolone could feasibly have a direct impact on activity in these regions. Indeed, in our sample, allopregnanolone serum level was more strongly correlated to amygdala activity than activity in any other brain region. Preclinical research suggests that the amygdala may be a particular target of allopregnanolone’s anxiolytic effects (30). In rats, microinfusions of allopregnanolone directly into the amygdala produce anxiolytic (30) antidepressant (31) and anti-aggressive (32) effects. In previous neuroimaging studies, greater endogenous allopregnanolone has been reported to be associated with lower amygdala reactivity (33, 41) and greater coupling between amygdala and dmPFC (34). Though we did not directly test the GABAergic effect of our intervention, our findings illuminate potential neural pathways through which pregnenolone administration and resulting increases in allopregnanolone levels could feasibly impact GABAergic transmission in a manner that is relevant to pathological anxiety."
The neurosteroid allopregnanolone is a potent allosteric modulator of the GABA(A) receptor with anxiolytic properties. Exogenous administration of allopregnanolone reduces anxiety, and allopregnanolone blockade impairs social and affective ...
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