Tuesday, July 12, 2011

Influence of GABA in the nucleus of the solitary tract on blood pressure in baroreceptor-denervated rats

In this article by Ito and Sved, they investigated the affects of 10 pmol Bicuculline (bic) , a GABA antagonist and glutamate (glu)  in the NTS of baroreceptor intact, chronic SAD and acute SAD animals. What they found is that the with the microinjections of bic the chronic animals had a greater decrease in MAP and HR compared to the control animals. They also compared the effect of bic of not only the control and chronic SAD, they also showed the change in MAP for partial, near complete and acute SAD animals. the chronic SAD had the greatest change in MAP followed by near complete SAD, partial SAD, acute SAD and then the control. Then they did a dose response with glu using 10 pmol, 50 pmol, and 200 pmol concentrations. The different groups responded similarly as they did to bic for each dose with the exception of 200 pmol. At 200 pmol the chronic SAD still has the greatest change in MAP but instead of the near complete SAD coming in second the acute SAD is next followed by the near complete SAD and the previous pattern continues. So these findings show that in the intact animals GABA is not playing an important role in tonic control of blood pressure. In the chronic SADs the Gaba A rectors is up regulated and plays a role in the control of bp.
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2 comments:

  1. Mueller LabJuly 14, 2011 at 11:48 PM

    Hi Mary, I have a few basic questions, Can you briefly explain the difference between chronic SAD and acute SAD animals? What anesthesia was used in this experiment? Why do they give glutamate if they want to study the influence of GABA in the NTS on blood pressure in baroreceptor-denervated rats? - Madhan

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  2. Mueller LabJuly 19, 2011 at 9:39 AM

    Chronic SADs are allowed to recover from surgery for 10-14 days.The acute SADs are allowed to recover for 2 hrs prior to the microinjections. They used halothane the same way we use isoflourane and then they switched the animal to chloralose and tubocurine via IV. As for the glutamate question, they wanted to maximally activate the NTS to get a a max response and when they gave BIC, they again wanted to see a max response. Then by comparing the different types of SADs tocontrol you will see that there is a difference. So by preventing the binding of GABA in the NTS in the SADs there have a greater decrease in bp when compared to the control meaning that GABA plays a important role in the SADs to help maintain bp. Just so you know they never injected gaba either or any gaba agonist.

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