Posted by linkadge on August 21, 2007, at 19:37:22
In reply to Re: SSRIs and bone loss » linkadge, posted by Quintal on August 21, 2007, at 18:38:09
>I remember you saying that SSRIs could cause >adrenal fatigue or something like that a while >ago, because they increase cortisol >release/production? And the HPA axis controls >cortisol release/production? I've read that >serotonin is the neurotransmitter that modulates >stress response, by activating the HPA axis and >increasing cortisol. So that is an interesting >link. How to explain the differential effects of >the secondary-amine TCAs/tertiary-amine TCAs on >serotonin though? Secondary-amine TCAs have less >affinity for the serotonin transporter don't >they?
But the HPA regulating effects of the TCA's are probably unrelated to their effects on monamine uptake. The TCA trimipramine shares with other TCA's the ability to regulate genes responsable for HPA axis regulation, wherase the SSRI's don't have any class effect on the HPA axis.
>Yet in that study they were associated with a >higher incidence of hip fractures than tertiary->amine TCAs, which have greater affinity for the >serotonin transporter, if my source is correct.
Not exactly sure. Old data may be less direct or comprehensive. One wouldn't expect the less anticholinergic tertiary TCA's to produce more falls. I would tend to think that the correlation is not directly related to affinity for the serotonin uptake pump.
Perhaps, because the tertiary amines are better tollerated, they can be used in higher doses?
>So what to make of it? Do they have different >effects on the HPA axis independent of the >serotonin transporter? Or is some other >mechanism at play, or more likely a combination >of mechanisms.
Not sure. Did they comapre those treated with AD's to age matched depression sevarity matched drug free controls? (I didn't read all of above data). Ie to exclude the possability that depression itself isn't the cause of the bone loss?
Linkadge
poster:linkadge
thread:777598
URL: http://www.dr-bob.org/babble/20070815/msgs/777660.html