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Could a male fertility pill adversely affect inhibition via allopregnanolone levels?

kofi kofi at anon.un
Fri Oct 17 11:53:19 EST 2003

One more abstract.  Did I mention TMJ featured an increase of Substance 

Pain. 2001 Aug;93(2):191-6. Related Articles, Links
    Click here to read 
    Gabapentin inhibits the substance P-facilitated K(+)-evoked release 
of [(3)H]glutamate from rat caudial trigeminal nucleus slices.

    Maneuf YP, Hughes J, McKnight AT.

    Pfizer Global Research & Development, Cambridge Laboratories, 
Cambridge University Forvie Site, Robinson Way, Cambridge CB2 2QB, UK.

    The effect of gabapentin on the release of the spinal sensory 
neurotransmitter glutamate has been investigated in an in vitro model 
using a perfused thin slice preparation from the rat brainstem 
containing the spinal trigeminal caudal subnucleus (Sp5C) and 
pre-incubated with [(3)H]glutamate. Addition of excess K(+) to the 
perfusing solution increased the content of tritium in the perfusate. 
The prior addition of substance P increased this index of glutamate 
release in a concentration-dependent manner, with the mean maximum of 
around 50% increase obtained at 1-3 microM. The action of substance P to 
increase the evoked release of glutamate was blocked by the antagonist 
CP-99994, suggesting a specific involvement of the NK(1) receptor in 
mediating the facilitatory effect. On its own, gabapentin at up to 100 
microM did not modify the baseline level of K(+)-evoked release of 
glutamate; however, gabapentin caused a concentration-dependent decrease 
of the facilitatory effect of substance P (EC(50)=6.49 microM). The 
R-(-)- and S-(+)-isomers of 3-isobutylgaba were then tested against the 
increase in K(+)-evoked release of glutamate by substance P. 
S-(+)-3-isobutylgaba (pregabalin) at 30 microM acted like gabapentin to 
reduce the substance P-mediated increase of release almost to the 
baseline level of K(+)-evoked release, while in contrast the 
R-(-)-isomer at this concentration produced no reduction, and rather a 
trend towards a further enhancement of the potentiating effect of 
substance P. In conclusion, we have found and characterized an effect of 
gabapentin that is of possible mechanistic relevance to the 
anti-hyperalgesic/allodynic actions of this compound.

    PMID: 11427331 [PubMed - indexed for MEDLINE]

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