This chemical metergoline is a very interesting substance and is a continuation of my search for chemicals that combine several beneficial characteristics into a single molecule/entity. Metergoline belongs to the same class of drugs as bromocriptine, lisuride, cabergoline, terguride, etc. However, unlike them it is an antagonist at the serotonin receptors 5-HT1, 5-HT2, 5-HT6, and 5-HT7. Most ergot drugs are agonists on those receptors with the possible (and partial) exception of lisuride. More importantly, just like lisuride metergoline is an antagonist at the dreaded 5-HT2B receptor. This may endow it with anti-fibrotic properties similar to lisuride, terguride, ritanserin and cyproheptadine. In addition, unlike other serotonin antagonist that simply block serotonin receptors metergoline is actually capable of also reducing serotonin synthesis. The putative dopamine agonism is probably responsible at least partially for this effect. Furthermore, metergoline has been shown to lower prolactin in humans and animal models, with effectiveness similar to bromocriptine when used in the same doses. Preliminary research suggests that metergoline is an agonist at the D2 receptor, which is not surprising given its similarity to lisuride, bromocriptine, etc. However, its exact dopamine receptor agonism profile is not well-known. What is even more interesting is that metergoline is capable of lowering prolactin through a (currently unknown) non-dopaminergic mechanism. So, it represents a viable alternative with less risk for dopamine receptor downregulation.

Some other interesting properties (according to the published studies) include ability to lower cortisol in doses as low as 2mg daily, improve insulin sensitivity in animal models, and act as an antidepressant.
Finally, metergoline possesses activity against the Candida strain of fungi and especially the potentially lethal strain Candida krusei, which typically kills 50% - 60% of the people it infects and is naturally resistant to antifungals like fluconazole. As far as I know, metergoline is unique among all ergot derivatives in its anti-fungal properties.

Metergoline - Wikipedia, the free encyclopedia
metergoline (CHEBI:64216)
metergoline
"...Summary: A dopamine agonist and serotonin antagonist. It has been used similarly to BROMOCRIPTINE as a dopamine agonist and also for MIGRAINE DISORDERS therapy."

The units listed on the label are just for measurement purposes. They do not indicate or suggest optimal dose. Please note that similar to the liquid products sold by companies like Sigma Aldrich, Spectrum Chemical, Alfa Aesar, etc, this product if for lab/research use only.

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Metergoline is a non-selective serotonin antagonist and putative dopamine agonist. As a serotonin antagonist it targets the 5-HT1, 5-HT2, 5-HT6, and 5-HT7 receptors but due to its general antiserotonin effects it is considered a non-specific serotonin antagonist similar to cyproheptadine. The dopamine agonism profile of metergoline is not well-known except some evidence for D2 receptor agonism. Metergoline is capable of lowering prolactin through both dopaminergic and non-dopaminergic mechanisms and displays similar effectiveness to bromocriptine in the same dose range, and the two drugs are considered synergistic. One of the most interesting properties of metergoline is its antifungal activity against Candida strains, which are naturally resistant to anti-fungal drugs.

Drops per container: about 250
Each drop contains the following ingredients:

Metergoline: 0.45 mg

Other ingredients: add product to shopping cart to see info
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REFERENCES:

Miscellaneous
https://www.ncbi.nlm.nih.gov/pubmed/24909513
The effects of metergoline and 8-OH-DPAT injections into arcuate nucleus and lateral hypothalamic area on feeding in female rats during the estrous... - PubMed - NCBI
Serotonin antagonist-induced lowering of prolactin secretion does not affect the pattern of pulsatile secretion of follicle-stimulating hormone and... - PubMed - NCBI
Serotoninergic modulation of sodium appetite in the rat. - PubMed - NCBI
Further evidence for an inhibitory role of central 5-HT in male rat sexual behavior. - PubMed - NCBI

Neurological/Brain
https://www.ncbi.nlm.nih.gov/pubmed/16921395
Naloxone and metergoline effects on growth hormone response to gamma-hydroxybutyric acid. - PubMed - NCBI
The effects of metergoline combined with PGF2alpha treatment on luteal function and gestation in pregnant ********. - PubMed - NCBI
Stimulation of serotonin1A receptors increases release of prolactin in the rat. - PubMed - NCBI
Does metergoline selectively attenuate 5-HT mediated prolactin release? - PubMed - NCBI
Metergoline abolishes the prolactin response to buspirone. - PubMed - NCBI
Activation of 5-HT 1 serotonin receptors in the medial basal hypothalamus stimulates prolactin secretion in the unanaesthetized rat. - PubMed - NCBI
Metergoline as an inhibitor of prolactin release. - PubMed - NCBI
The effect of metergoline on endocrine responses to L-tryptophan. - PubMed - NCBI
The behavioural effects of intravenously administered tryptamine in mice. - PubMed - NCBI
Serotonin initiates and autoamplifies its own synthesis during mouse central nervous system development. - PubMed - NCBI
Treatment of hyperprolactinemic amenorrhea with Metergoline. - PubMed - NCBI
Metergoline, pirenperone and pizotifen alter dopamine and 5-hydroxytryptamine synthesis in discrete rat brain nuclei. - PubMed - NCBI
Intolerance of bromocriptine: is metergoline a satisfactory alternative? - PubMed - NCBI
Metergoline as an alternative to bromocriptine in amenorrhoea. - PubMed - NCBI
Effect of metergoline on prolactin, follicle stimulating hormone, luteinizing hormone and thyroid stimulating hormone response to TRH and LHRH in n... - PubMed - NCBI
Treatment of hyperprolactinaemia with metergoline for periods up to 5 years: clinical and biological tolerability. - PubMed - NCBI
Metergoline as a lactation inhibitor. - PubMed - NCBI
Treatment of hyperprolactinemic states with different drugs: a study with bromocriptine, metergoline, and lisuride. - PubMed - NCBI
Metergoline and cyproheptadine suppress prolactin release by a non-5-hydroxytryptaminergic, non-dopaminergic mechanism. - PubMed - NCBI
Effect of metergoline on serum prolactin stimulated by TRH. - PubMed - NCBI
Prolactin suppression by serotonin antagonists in man: further evidence for serotoninergic control of prolactin secretion. - PubMed - NCBI
Growth hormone and prolactin release in acromegalic patients following metergoline administration. - PubMed - NCBI

https://www.ncbi.nlm.nih.gov/pubmed/3924253
"...As metergoline acts predominantly as a serotonin antagonist it might be expected to have additive or synergistic effects when combiend with bromocriptine. Although it has some dopaminergic activity, this is probably not the mechanism that suppressed prolactin. Interestingly, the prolactin concentration in one patient was reduced further when 2.5mg bromocriptine was added to treatment...Metergoline provides satisfactory treatment for many patients unable to tolerate bromocriptine and should beuseful in the management of hyperprolactinaemia either alone or combined with a small dose of bromocriptine."

https://pubmed.ncbi.nlm.nih.gov/662027/ (MET decreases serotonin synthesis as well)
Metergoline inhibition of thyrotrophin and prolactin secretions in primary hypothyroidism. - PubMed - NCBI (prometabolic - lowers TRH)

Mood/Cognition/Behavior/Addiction
https://www.ncbi.nlm.nih.gov/pubmed/11910270
Regulation of Human Kv1.4 Channel Activity by the Antidepressant Metergoline. - PubMed - NCBI
Cocaine modulates mammalian circadian clock timing by decreasing serotonin transport in the SCN. - PubMed - NCBI
An investigation into the effects of 5-HT agonists and receptor antagonists on ethanol self-administration in the rat. - PubMed - NCBI
Metergoline antagonizes fluoxetine-induced suppression of food intake but not changes in the behavioural satiety sequence. - PubMed - NCBI
Metergoline potentiates natural feeding and antagonizes the anorectic action of medical hypothalamic 5-hydroxytryptamine. - PubMed - NCBI
Effects of 5-HT receptor antagonists on morphine-induced tolerance in mice. - PubMed - NCBI
Effects of serotonin and the serotonin blocker metergoline on meal patterns and macronutrient selection. - PubMed - NCBI
Partial reversal of fluoxetine anorexia by the 5-HT antagonist metergoline. - PubMed - NCBI
Metergoline blocks the behavioral and neuroendocrine effects of orally administered m-chlorophenylpiperazine in patients with obsessive-compulsive ... - PubMed - NCBI
Dopaminergic mechanism of imipramine action in an animal model of depression. - PubMed - NCBI
Increased food intake and carbohydrate preference in the rat following treatment with the serotonin antagonist metergoline. - PubMed - NCBI
Animal model of anxiety: effect of metergoline in the genetically hypertensive rats of Koletsky type and in the rats of Wistar strain. - PubMed - NCBI
Increased food intake in satiated rats induced by the 5-HT antagonists methysergide, metergoline and ritanserin. - PubMed - NCBI
Serotonergic modulation of yawning. - PubMed - NCBI

CVD/Circulation/Hypertension/Calcification
https://www.ncbi.nlm.nih.gov/pubmed/2412045
Effect of metergoline on the aldosterone-stimulating properties of metoclopramide. - PubMed - NCBI
Pharmacological evidence that stimulation of central serotonergic pathways increases renin secretion. - PubMed - NCBI

Fibrosis/Cancer
https://www.ncbi.nlm.nih.gov/pubmed/7805767
Nicotine stimulates a serotonergic autocrine loop in human small-cell lung carcinoma. - PubMed - NCBI
[Metergoline in hyperprolactinemic breast cancer: a phase II study]. - PubMed - NCBI

Metabolism/Diabetes/Cortisol/Insulin/Obesity
https://www.ncbi.nlm.nih.gov/pubmed/499287
The effects of metergoline and other serotonin receptor antagonists on serum corticosterone in rats. - PubMed - NCBI
Serotonin mediated changes in corticotropin releasing factor mRNA expression and feeding behavior isolated to the hypothalamic paraventricular nuclei. - PubMed - NCBI
Effects of the non-selective 5-HT receptor agonist, 5-carboxamidotryptamine, on plasma glucose levels in rats. - PubMed - NCBI
Effect of selective serotonin agonists on basal, corticotrophin-releasing hormone- and vasopressin-induced ACTH release in vitro from rat pituitary... - PubMed - NCBI
Stimulation of the hypothalamo-pituitary-adrenocortical axis by the central serotonergic pathway: involvement of endogenous corticotropin-releasing... - PubMed - NCBI
Effects of serotonergic agonists and antagonists on corticotropin-releasing hormone secretion by explanted rat hypothalami. - PubMed - NCBI
Stimulation of corticosterone and beta-endorphin secretion in the rat by selective 5-HT receptor subtype activation. - PubMed - NCBI
Effect of an antiserotoninergic drug, metergoline, on the ACTH and cortisol response to insulin hypoglycemia and lysine-vasopressin in man. - PubMed - NCBI
Effect of metergoline, a powerful and long-acting antiserotoninergic agent, on insulin secretion in normal subjects and in patients with chemical d... - PubMed - NCBI

Digestion/GI
https://www.ncbi.nlm.nih.gov/pubmed/17965538
Serotonin inhibits gastric acid secretion through a 5-hydroxytryptamine1-like receptor in the rat. - PubMed - NCBI

Immune/Antirival/Antibacterial/Antiparasitic
https://www.ncbi.nlm.nih.gov/pubmed/21354537
In vitro synergistic effects of metergoline and antifungal agents against Candida krusei. - PubMed - NCBI
http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004063