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H3 (histamine) antagonist?

searcher

Senior Member
Messages
567
Location
SF Bay Area
There have been assorted threads on histamine that has renewed my interest in the possible contribution of histamine to my symptoms. I have tried H1 and H2 blockers with no obvious effects other than a mild reduction in my GERD. I looked up H3 antagonists and the wikipedia entry on it was fascinating to me. H3 antagonists appear to help sleep disorders, ADHD, overeating, and neuropathic pain. There is research underway to see if it can help modulate wakefullness.
Has anyone tried an H3 antagonist? What I can't tell is whether the existing H3 antagonists are all for research, or whether some are available OTC, or at least via prescription.
I realize that the methylation protocol should help with breakdown of histamine, but I've taken metafolin, methyl b-12, and other co-factors for 9 months with no significant effect. Until I can determine what is blocking my recovery, it would be great to have something that can remove most of the symptoms. I am a little skeptical of daosin, but will try that out as well.

Thanks!
 

Sushi

Moderation Resource Albuquerque
Messages
19,935
Location
Albuquerque
I looked up H3 antagonists and the wikipedia entry on it was fascinating to me. H3 antagonists appear to help sleep disorders, ADHD, overeating, and neuropathic pain. There is research underway to see if it can help modulate wakefullness.
Has anyone tried an H3 antagonist? What I can't tell is whether the existing H3 antagonists are all for research, or whether some are available OTC, or at least via prescription.

Thanks!

I have also been reading about the function of the H3 receptor and it looks very interesting in relation to some of our symptoms.

I don't know of any commercially available H3 agonists, and one wiki article says: http://en.wikipedia.org/wiki/Histamine_H3_receptor

Agonists

There are currently no therapeutic products acting as selective agonists for H3 receptors, although there are several compounds used as research tools which are reasonably selective agonists. Some examples are:

(R)-?-methylhistamine
Cipralisant (initially assessed as H3 antagonist, later found to be an agonist, shows functional selectivity, activating some G-protein coupled pathways but not others)[6]
Immepip
Imetit
Immethridine
Methimepip
Proxyfan (complex functional selectivity; partial agonist effects on cAMP inhibition and MAPK activity, antagonist on histamine release, and inverse agonist on arachidonic acid release)


Looking up the first one, http://www.tocris.com/dispprod.php?ItemId=1631, it looks like you can buy it. "Very potent, high affinity H3 agonist (KD = 50.3 nM) that displays > 200-fold selectivity over H4 receptors. Inhibits H3-mediated histamine synthesis and release in the CNS and stimulates H4-mediated eosinophil shape change (EC50 = 66 nM)."

I think I would want some medical supervision to try it though. I wonder why this doesn't seem to have been more explored for our CNS problems?

Sushi
 

redo

Senior Member
Messages
874
What I can't tell is whether the existing H3 antagonists are all for research, or whether some are available OTC, or at least via prescription.
I realize that the methylation protocol should help with breakdown of histamine, but I've taken metafolin, methyl b-12, and other co-factors for 9 months with no significant effect. Until I can determine what is blocking my recovery, it would be great to have something that can remove most of the symptoms. I am a little skeptical of daosin, but will try that out as well.

Thanks!

Some of the ones on the list are available. I think it makes great sense to try them out. I get a lot better with some ordinary antiahistamines (primarily sleep and somewhat better consentration), and I am thinking about giving some of those which are H3 antagonists a go.

If you browse down to where it says histaminergic, at the bottom of this article, and click show, a somewhat larger list of H3 antagonists will show.
http://en.wikipedia.org/wiki/Histaminergic
 

RustyJ

Contaminated Cell Line 'RustyJ'
Messages
1,200
Location
Mackay, Aust
I take H2 antagonists for stomach, and for years took H1 antagonists for sinus etc. I am interested in H3 antagonists. I wonder if it would help with brain fog, or OI? From the brief description below, it does seem very interesting. Not a cure, more of a calmative.

Betahistine may be available from compounding chemist, by prescription (in Australia). Apparently it is quite cheap. If anyone is using it, please post here about your experiences.

Betahistine has a very strong affinity as an antagonist for histamine H3 receptors and a weak affinity as an agonist for histamine H1 receptors. Betahistine seems to dilate the blood vessels within the middle ear which can relieve pressure from excess fluid and act on the smooth muscle.

Betahistine has two modes of action. Primarily, it has a direct stimulating (agonistic) effect on H1 receptors located on blood vessels in the inner ear. This gives rise to local vasodilation and increased permeability, which helps to reverse the underlying problem of endolymphatic hydrops.

In addition, betahistine has a powerful antagonistic effects at H3 receptors, and increases the levels of neurotransmitters released from the nerve endings. This is thought to have two consequences;

The increased amounts of histamine released from histaminergic nerve endings can stimulate H1 receptors, thus augmenting the direct agonistic effects of betahistine on these receptors. This explains the potent vasodilatory effects of betahistine in the inner ear, which are well documented.

It is postulated that betahistine increases the levels of neurotransmitters such as serotonin in the brainstem, which inhibits the activity of vestibular nuclei.