Posted by JohnX2 on March 25, 2002, at 6:14:04
In reply to long term AD upreg of d2 receptors,etc?, posted by JohnX2 on March 25, 2002, at 2:34:32
They got no AD effect at all on this experiment!John
Dizocilpine antagonizes the effect of chronic imipramine on learned helplessness in rats.Meloni D, Gambarana C, De Montis MG, Dal Pra P, Taddei I, Tagliamonte A.
Institute of Pharmacology, University of Siena, Italy.
Dizocilpine coadministered with imipramine (IMI) through an SC-implanted osmotic minipump completely prevents the occurrence of behavioral supersensitivity to quinpirole, as well as the decrease of dopamine D1 and beta-adrenergic receptor function. The present report shows that, in the same experimental conditions, dizocilpine completely antagonized the capacity of IMI to prevent the development of the learned helplessness behavior in rats. Thus suggesting that the blockade of NMDA receptors also antagonizes the antidepressant effect of IMI. Interestingly, rats acutely treated with dizocilpine 30 min before the inescapable shock session behaved similarly to naive animals during the escape test session.
PMID: 7903459 [PubMed - indexed for MEDLINE]
> What happens if these ADs go too far.
> Too much D2 upregulation, D1 downregulation, etc.
> Poop out?
> Thoughts?
>
> John
>
>
> http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8096430&dopt=Abstract
>
> Long-term imipramine effects are prevented by NMDA receptor blockade.
>
> De Montis MG, Gambarana C, Meloni D, Taddei I, Tagliamonte A.
>
> Institute of Pharmacology, University of Siena, Italy.
>
> Long-term exposure to different antidepressant treatments induces increased motor response to central stimulants, due to a selective supersensitivity of dopamine D2 receptors in the limbic areas. Such an effect is accompanied by down-regulation of dopamine D1 receptor number, and by a decreased response of adenylyl cyclase to dopamine stimulation in the limbic system. Moreover, the number of beta-adrenergic receptors and the response of adenylyl cyclase to beta-adrenergic stimulation in the cortex result to be reduced. The present data confirms that imipramine (10 mg/kg twice a day for 3 weeks) produces such effects, and shows that the co-administration of imipramine with MK-801 (administered by a subcutaneously implanted osmotic minipump delivering 0.05 mg/kg/day of the compound) prevented the occurrence of both the behavioral supersensitivity to quinpirole, and the decrease of dopamine D1 and beta-adrenergic receptor function.
>
> PMID: 8096430 [PubMed - indexed for MEDLINE]
poster:JohnX2
thread:99985
URL: http://www.dr-bob.org/babble/20020322/msgs/99997.html