5HT Levels Research Articles

Acetylcholine and 5-hydroxytryptamine levels of the lateral geniculate bodies and superior colliculus of cats after visual deafferentation

Acetylcholine (ACh) and 5-hydroxytryptamine (5HT) levels were determined by bioassay in the lateral geniculate bodies, superior colliculus and occipital cortex of cats transected at midpontine pretrigeminal level. Three hours after visual deafferentation ACh levels were higher than in cats with intact visual apparatus. The difference was very large in the lateral geniculate body and small in the superior colliculus and cortex. No differences were found between the levels of 5HT. Visual deafferentation in midpontine pretrigeminal cats is followed by a long lasting EEG synchronization. If the synchronization was interrupted by an infusion of dl 3,4 dihydoxyphenylalanine no differences were found between the ACh contents in cats with visual deafferentation and cats with intact eyes. On the other hand, higher ACh contents were found in the lateral geniculate body of cerveau isolé cats with intact eyes in which the transection caused a permanent synchronization. The geniculate ACh content does not seem influenced, therefore, by visual deafferentation but by the degree of activation of the cats. These results suggest that a large part of ACh present in the lateral geniculate body might be related with fibers originating from the reticular formation.

THE 5-HYDROXYTRYPTAMINE CONTENT OF THE PLACENTA AND FOETUS DURING PREGNANCY IN MICE.

5-Hydroxytryptamine (5HT) levels were measured in blood and tissues from pregnant mice. Blood levels remained constant during pregnancy and were the same as those in nonpregnant female mice. Placental levels of 5HT increased throughout pregnancy as did the foetal levels. The maternal blood volume of the placenta also increased with advancing gestation. 5HT levels were measured after treatment of the mother with 5HT, and the critical placental level of 5HT observed at about the time of death of the foetus was determined. The levels of 5HT in the placenta and foetus after treatment of the mother with several monoamine oxidase inhibitors were measured, and found to show no significant increase above the normal levels in these tissues. Treatment with cyproheptadine, a 5HT antagonist, did not delay parturition.