Ge. Crippa et al., Cardiovascular response to the injection of acetylcholine into the anterior cingulate region of the medial prefrontal cortex of unanesthetized rats, CEREB CORT, 9(4), 1999, pp. 362-365
Injection of acetylcholine (ACh) (2.5-60 nmol) into the anterior cingulate
cortex caused dose dependent hypotensive responses (E-max = -25.3 mmHg) and
no change in the heart rate. The hypotensive response to 30 nmol of ACh wa
s blocked by local pretreatment with atropine (3 nmol) or 4-DAMP (6.7 nmol)
, a non-tropine muscarinic antagonist. When the same dose of atropine was i
njected i.v., no changes were observed in the hypotensive response to intra
cortical ACh. This observation rules out the possible leakage of ACh into t
he peripheral circulation and favors the idea of a cortical site of action.
The injection of the same dose of ACh into the corpus callosum or the occi
pital cortex did not cause changes in the cardiovascular system. The presen
t results confirm earlier evidence that the cingulate cortex is involved in
the control of the autonomic system and indicate that cholinergic muscarin
ic receptors in the cingulate cortex mediate a hypotensive response without
a change in heart rate.