メディエイゴ

The "raging hormones(1)" of puberty(2) are known to produce mood swings(3) and stress for most teenagers, making it difficult to cope with(4) this period of life. Until now, the specific causes of pubertal(5) anxiety(6) have not been identified(7), making it harder to understand and treat adolescent angst(8).

In the current edition of the journal Nature Neuroscience, researchers led by(9) Sheryl S. Smith, PhD, professor of physiology(10) and pharmacology(11) at SUNY Downstate Medical Center, report findings demonstrating that a hormone normally released(12) in response to(13) stress, THP(14), actually reverses(15) its effect at puberty, when it increases anxiety.

This hormone normally acts like a tranquilizer(16), acting at(17) sites in the brain that "calm" brain activity(18). In the adult, this stress hormone helps the individual adapt to(19) stress, with a calming effect(20) produced half an hour after the event.

Specifically(21), the GABA-A receptor(22) is the target for steroids, such as THP (or(23) allopregnanolone), which reduce anxiety. GABA-A receptors calm activity in the brain. As such(24), they are the targets for most sedative(25), tranquilizing(26) drugs.

One sub-type, GABA-A receptors containing the delta subunit, such as alpha4-beta2-delta, has the highest sensitivity(27) to steroids. In order to study its role in puberty, the researchers used a mouse model that reliably(28) predicts(29) the human condition. In this rodent model(30), the alpha4-beta2-delta receptor normally has very low expression(31), but increases dramatically(32) at the onset of(33) puberty in the part of the brain that regulates(34) emotion. Paradoxically(35), THP reduced the inhibition(36) produced by these alpha4-beta2-delta GABA-A receptors, increasing brain activity to produce a state of(37) increased anxiety.