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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 10 of 10. This is the beginning of the thread.
Posted by iforgotmypassword on October 14, 2005, at 2:43:31
sorry, thats my question. i can;t write more thanx
Posted by rod on October 14, 2005, at 9:15:55
In reply to are maoi's pro-histamine?, posted by iforgotmypassword on October 14, 2005, at 2:43:31
> sorry, thats my question. i can;t write more thanx
as far as I know Selegiline stimulates the H2 receptor in the stomache (and probably somewhere else too)....
Roli
Posted by naughtypuppy on October 14, 2005, at 9:29:29
In reply to are maoi's pro-histamine?, posted by iforgotmypassword on October 14, 2005, at 2:43:31
> sorry, thats my question. i can;t write more thanx
Interesting that you should ask this question. I had to go off of Parnate recently partially because of what my Pdoc described as it causing an enhanced allergic response. He has seen this rarely in patients before, but he could find no documentation whatsoever about this particular side effect inspite of extensive searches in his med school library and the internet. What medication are you on and what are the allergic symptoms?
Posted by SLS on October 14, 2005, at 11:24:13
In reply to are maoi's pro-histamine?, posted by iforgotmypassword on October 14, 2005, at 2:43:31
I couldn't find anything indicating that Parnate acted as a pro-histaminergic. On the contrary, it seems to be anti-histaminergic via prostaglandin synthesis inhibition. Nardil seems to be neutral.
- Scott
Posted by djmmm on October 14, 2005, at 13:03:19
In reply to are maoi's pro-histamine?, posted by iforgotmypassword on October 14, 2005, at 2:43:31
Since histamine is a monoamine-- specifically, I believe it's an indoleamine (like serotonin)-- I'm guessing taking a MAOI would increase histamine levels.
Posted by Declan on October 14, 2005, at 14:05:47
In reply to Re: are maoi's pro-histamine?, posted by djmmm on October 14, 2005, at 13:03:19
This morning I dissolved a Parnate under my tongue. My sinuses reacted with a bit of mucous production, but they often do, to Valium for example when taken that way. My immune system is probably out of whack.
I dunno if this says anything about MAOIs in particular.
Declan
Posted by zeugma on October 14, 2005, at 18:07:06
In reply to Re: are maoi's pro-histamine? » iforgotmypassword, posted by naughtypuppy on October 14, 2005, at 9:29:29
interesting discussion, provigil is pro-histamine, and it made hay fever season hell. in the summer and early fall the drug gives me severe rhinitis, and a vaguely ill felling.
i had no idea histamine was an indoleamine.
-z
Posted by ed_uk on October 15, 2005, at 13:57:10
In reply to Re: are maoi's pro-histamine?, posted by zeugma on October 14, 2005, at 18:07:06
Hi Zeugie!
>i had no idea histamine was an indoleamine
It's not - but it is an amine. Serotonin and melatonin are indoleamines, derived from the amino acid tryptophan.
Epinephrine, norepinephrine and dopamine are catecholamines.
Serotonin, melatonin, NE, DA and histamine are all amines.... but they are different types of amines.
Kind regards
~Ed
Posted by zeugma on October 15, 2005, at 16:21:10
In reply to Re: are maoi's pro-histamine? » zeugma, posted by ed_uk on October 15, 2005, at 13:57:10
hi Ed,
thanks for the clarification.
so melatonin is an indoleamine? but MAOI's wouldn't necessarily boost melatonin, would they?
One of the more fascinating things I pulled up from PubMed's search engine is that caffeine actually boosts melatonin- through interactions with the 1A2 enzyme that also inactivates melatonin:
J Endocrinol Invest. 2003 May;26(5):403-6. Related Articles, Links
Caffeine raises the serum melatonin level in healthy subjects: an indication of melatonin metabolism by cytochrome P450(CYP)1A2.Ursing C, Wikner J, Brismar K, Rojdmark S.
Karolinska Institutet, Department of Internal Medicine, Endocrinology Section, Stockholm Soder Hospital, Stockholm, Sweden. carina.ursing@medklin.sos.sll.se
Caffeine is metabolized in the liver by cytochrome P450(CYP)1A2. Recent findings imply that this enzyme may also be of importance for the metabolism of human melatonin (MT). If caffeine and MT are metabolized by the same enzyme, one may expect to find different serum MT levels after ingestion of coffee compared with placebo. Although coffee is consumed by people all over the world, few studies have focused on whether caffeine actually affects serum MT levels in normal subjects. We decided to study that particular topic. For that purpose 12 healthy individuals were tested on two occasions, one week apart. On one of these occasions they were given a capsule containing 200 mg caffeine in the evening. On the other, they received placebo. The experimental order was randomized. Serum MT levels were determined every second hour between 22:00 h and 08:00 h, and the melatonin areas under the curve (MT-AUCs) were calculated. After caffeine the serum MT level rose from 0.09 +/- 0.03 nmol/l at 22:00 h to 0.48 +/- 0.07 nmol/l at 04:00 h. The corresponding rise after placebo was less prominent (from 0.06 +/- 0.01 to 0.35 +/- 0.06 nmol/l). This was reflected by the MT-AUC which was 32% larger after ingestion of caffeine compared with placebo (MT-AUC(caffeine) 3.16 +/- 0.44 nmol/l x h vs MT-AUC(placebo) 2.39 +/- 0.40 nmol/l x h; p < 0.02). These findings imply that caffeine, ingested in the evening at a dose corresponding to two ordinary cups of coffee, augments the nocturnal serum MT level, which in turn supports the notion that cytochrome P450(CYP)1A2 is involved in the hepatic metabolism of human MT.
Maybe this is in part responsible for caffeine's antidepressant effect. Incidentally Provigil induces 1A2 so it probably lowers melatonin levels. Fluvoxamine probably raises melatonin, unless it has another mechanism that counteracts this.
This is one of those days where I wish I knew where I was talking about.
-z
Posted by ed_uk on October 15, 2005, at 16:48:59
In reply to Re: are maoi's pro-histamine? » ed_uk, posted by zeugma on October 15, 2005, at 16:21:10
Hi Z!
That's really interesting. I was (previously) under the impression that caffeine reduced melatonin levels.
Too much caffeine makes me tired. I wonder whether this is due to melatonin?
>Fluvoxamine probably raises melatonin.....
I've read that it does!
Kind regards
~Ed
This is the end of the thread.
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