Key result
Pharmacological inhibition of the prelimbic cortex significantly attenuated the pressor response to chemoreflex activation in conscious rats, whereas infralimbic inhibition had no effect.
The prelimbic cortex, but not the infralimbic cortex, mediates the pressor response to chemoreflex activation in conscious rats.
Does not support clinical translation; extends rodent chemoreflex models but leaves open human autonomic relevance.
The ventral portion of the medial prefrontal cortex comprises the prelimbic cortex (PL) and the infralimbic cortex (IL). Several studies have indicated that both the PL and the IL play an important role in cardiovascular control. Chemoreflex activation by systemic administration of potassium cyanide (KCN) evokes pressor and bradycardiac responses in conscious rats, in addition to an increase in respiratory frequency. We report here a comparison between the effects of pharmacological inhibition of PL and IL neurotransmission on blood pressure and heart rate responses evoked by chemoreflex activation using KCN (i.v.) in conscious rats. Bilateral microinjection of 200 nl of the unspecific synaptic blocker CoCl(2) (1 mm) into the PL evoked a significant attenuation of the pressor response, without affecting the chemoreflex-induced heart rate decrease. However, IL local synapse inhibition evoked no changes in cardiovascular responses induced by chemoreflex activation. Thus, our results suggest that the pressor but not the bradycardiac response to chemoreflex activation is, at least in part, mediated by local neurotransmission present in the PL cortex, without influence of the IL cortex.
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Granjeiro et al. (2011) studied Chemoreflex activation. Pharmacological inhibition of prelimbic (PL) and infralimbic (IL) neurotransmission using CoCl(2) was evaluated on Blood pressure and heart rate responses evoked by chemoreflex activation. Pharmacological inhibition of the prelimbic cortex significantly attenuated the pressor response to chemoreflex activation in conscious rats, whereas infralimbic inhibition had no effect.
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