Allopregnanolone is a neurosteroid, which is a type of steroid hormone that is produced in the brain. It is derived from progesterone, a hormone that is involved in the menstrual cycle and pregnancy. Allopregnanolone acts as a positive allosteric modulator of gamma-aminobutyric acid (GABA) receptors in the brain, enhancing the inhibitory effects of GABA, a neurotransmitter that reduces neural activity and has a calming effect.
The role of allopregnanolone in PMDD is significant due to its influence on mood and emotional regulation. Some researchers believe that the fluctuations in allopregnanolone levels during the menstrual cycle might play a role in the mood symptoms associated with PMDD. Here's how it works:
Hormonal Fluctuations: Allopregnanolone levels in the body rise and fall in response to the menstrual cycle. They tend to increase during the luteal phase (the second half of the menstrual cycle), which is when PMDD symptoms are most pronounced. This increase in allopregnanolone is due to the rise in progesterone levels during this phase.
GABAergic System: Allopregnanolone enhances the activity of GABA receptors in the brain. GABA is an inhibitory neurotransmitter that helps regulate the balance between excitatory and inhibitory signals in the brain. Increased allopregnanolone levels can lead to increased inhibitory effects of GABA, which can have a calming and sedative effect on the nervous system.
Mood Regulation: GABAergic activity is closely linked to mood regulation, anxiety reduction, and stress management. Altered GABAergic activity can affect emotional states, and disruptions in this system have been implicated in mood disorders, including PMDD.
Susceptibility to PMDD Symptoms: Some researchers propose that individuals with PMDD might be more sensitive to the fluctuations in allopregnanolone levels. The increased levels of allopregnanolone during the luteal phase could potentially lead to changes in GABAergic signalling that contribute to the mood symptoms experienced by individuals with PMDD, such as irritability, mood swings, and anxiety.
Research into the role of allopregnanolone in PMDD is ongoing, and it is just one of the factors that contribute to the complex nature of the disorder. While allopregnanolone's involvement in PMDD sheds light on its potential mechanisms, it's important to note that PMDD is likely influenced by multiple factors, including genetic predisposition, hormonal fluctuations, neurotransmitter activity, and environmental influences.