From: aankrom@nyx.cs.du.edu (Anthony Ankrom)
Subject: Re: Ketamine <Fwd from daniel>
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Date: Wed, 13 Jan 93 05:06:44 GMT

In article <1993Jan12.170336.10671@midway.uchicago.edu> bagg@midway.uchic
go.edu writes:
>In article <1993Jan11.171253.29783@oucsace.cs.ohiou.edu> bwhite@oucsace.
s.ohiou.edu (William E. White ) writes:
>
>>Of course, dextromethorphan (actually it may be dextrorphan) is also an
>>NMDA antagonist (I think it's also noncompetative), as is PCP.  There's
>>something else though; PCP stimulates sigma-opiate receptors and I thin

>>Ketamine may as well; I don't know about dextro[metho]rphan or MK801.
>>Some of the effects of PCP/ketamine may be due to sigma-opioid agonist
>>activity.
>
>Yes, there's been some controversy about whether the analgesic effects
>were due some opioid mechanism.  My impression is that this probably
>isn't the case since quadazocine blocks the "analgesic" effects of opioi
 
>drugs but not PCP in a tail flick paradigm in rhesus monkeys.  But I
>haven't been following this issue too closely.
>
>>And yes, there are cases of psychosis from long-term use of dextrometho
phan
>>recreationally (although nowhere near as much as with PCP).
>>
>>>conference which argued that MK-801 induced neurotoxicity on its own. 

>>>However, I'd be surprised if the poster wasn't confused here.
>>
>>I've never seen anything indicating that MK801 (or ketamine for that ma
ter)
>>is neurotoxic.  However, in [SO: Brain-Res-Mol-Brain-Res. 1992 Aug 14(4
:
>>363-8] it was reported that chronic use of NMDA antagonists causes 
>>synthesis of D2 receptors (in rat striatum).  I can't help but wonder i

>>acute use of PCP or ketamine might not affect dopaminergic systems.
>
>There's definitely some important interactions there.  PCP squirted into
>rats' nucleus accumbems causes dopamine release, according to microdilys
s
>studies.
>
>>-- 
>>|  Bill White   +1-614-594-3434     | bwhite@oucsace.cs.ohiou.edu      
      |
>>|  31 Curran Dr., Athens OH  45701  | bwhite@bigbird.cs.ohiou.edu (alte
nate) |
>>|  SCA: Erasmus Marwick, Dernehealde Pursuivant, Dernehealde, Middle Ki
gdom  |
>
>    --Matt
>


 This is an effect that only certain PCP-like substances display. PCP
inhibits the uptake of dopamine much like cocaine. TCP (2-thienyl
cyclohexyl piperidine) has a higher affinity for the PCP receptor, but
does not effect dopamine uptake appreciably. BTCP (2-benothiophenyl
cyclohexyl piperidine) inibits uptake of dopamine much like PCP, but has
very little affinity for the PCP receptor. Interestingly enough, BTCP is a
stronger DUI, but roughly 50 less potent than cocaine as a behavioural
stimulant. I apologise for not being able to cite the reference, but with
a little coaxing I can dig it up.

St. Anthony

     
--
          / N \   O                   Mi vsi smo krizhani,
         |   \ |  || Ph               chlani izbrani
         |   | |_O-C-C-OH             mesarskega ceha...
BZ        \ / /      Ph                            aankrom@nyx.cs.du.edu
Xref: sparky alt.drugs:20635 talk.bizarre:43835