The effects of lesions in the nucleus basalis of Meynert and physostigmine on rat frontal cortex acetylcholine level.
To clarify the relationship between acetylcholine (ACh) level in the frontal cortex and the area of lesion in the nucleus basalis of Meynert (nbM), we used ibotenic acid to bilaterally lesion the substantia innominata (SI), including the nbM, in rats and measured extracellular ACh by microdialysis. Baseline level of ACh (ACh-baseline) averaged 0.14 +/- 0.07 ng/40 microl/20 min (n=13) in the steady state. We also measured the size of the lesioned areas in the SI (nbM-lesion) by using a computed image analysis system. Both ACh level and nbM-lesion varied widely among animals. The bilateral nbM-lesion averaged 28 +/- 30% (n=13). The correlation coefficient between ACh-baseline and bilateral nbM-lesion was -0.871 (p<0.01). After intraperitoneal injection of physostigmine, maximum ACh levels increased to 0.18 +/- 0.06 ng/40 microl/20 min, and deltaACh (ACh-max/ACh-baseline) averaged 132 +/- 19% (n=8). There was no apparent correlation between deltaACh and bilateral nbM-lesion. These results show that the size of lesioned area in the bilateral SI was strongly correlated with the baseline ACh level in the frontal cortex, and indicate that the nbM is the major functional source of ACh in the frontal cortex. Our results also suggests that physostigmine possibly affects not only spared nbM-originated cholinergic fibers but also non-nbM-originated cholinergic fibers in the rat with the bilateral nbM lesion.
Kato
H
H
Department of Critical Care, Tokai University School of Medicine, Isehara, Kanagawa, Japan. hirotaka@is.icc.u-tokai.ac.jp
Aikawa
H
H
Shinohara
Y
Y
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D020532:Basal Nucleus of Meynert / Q000187:drug effects* / Q000473:pathology; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D005625:Frontal Lobe / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D010830:Physostigmine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D002800:Cholinesterase Inhibitors; D010830:Physostigmine; D000109:Acetylcholine