Tryptophan decarboxylase estrogens

Some women suffer from mental deprc.ssion when taking estrogen-containing oral contraceptives, and this depression could be due to another malfunction in tryptophan metabolism, leading to S-hydroxytryptamine (serotonin). Some evidence indicates that the decarboxylation of S-hydroxytrypto-phan is inhibited (in vitro) by estfogen conjugates competing with pyridoxal phosphate for the decarboxylase apoenzyme. 

By increasing the activity of the kynurenine pathway, estrogens could also increase the requirements for PLP and make less available to act as the coenzyme for 5-hydroxytryptophan decarboxylase, or estrogen conjugates could displace PLP from the decarboxylase coenzyme directly. Even though in nonhuman mammals tryptophan hydroxylase, not the decarboxylase, is thought to be rate-limiting in serotonin synthesis (Jl), levels of decarboxylase are said to be so low in human brain... 

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