In male rats, 3 weeks of methylene blue raised pituitary dopamine, cut D-2 receptor number and partly blocked estradiol-driven pituitary growth.
The same group found methylene blue alone left blood prolactin unchanged (abstract).
Methylene blue lowered blood prolactin by 65%, nearly tripled pituitary dopamine, and partially prevented estradiol-induced pituitary enlargement in rats.
After 21 days, male rats given methylene blue had 65% lower blood prolactin than controls: 1.7 vs. 4.9 ng/mL. Dopamine in the anterior pituitary was 2.7 times higher. In rats treated with estradiol, methylene blue also partially prevented pituitary enlargement and reduced prolactin buildup inside the gland. The dopamine increase occurred without a detectable increase in dopamine synthesis.
DOI: 10.1016/S0304-3940(01)01752-9.
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Nedvidkova et al., The role of dopamine in methylene blue-mediated inhibition of estradiol benzoate-induced anterior pituitary hyperplasia in rats, Neuroscience Letters 2001, Institute of Endocrinology, Prague (male rats; paywalled, abstract read; the blood-prolactin null is from the same group's 1993 Physiol Res paper, PMID 8218149).
pubmed.ncbi.nlm.nih.gov/1134…
Sep 24, 2026 · 2:30 AM UTC
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