Ha. Futuroneto et al., A COMPARISON OF THE EFFECTS OF ESERINE SULFATE ON THE ACTIVITY OF MEDULLARY RAPHE NEURONS IN THE ANESTHETIZED RABBIT AND RAT, Brazilian journal of medical and biological research, 27(6), 1994, pp. 1445-1454
1. Medullary raphe neurons are involved in the control of sympathetic
activity during desynchronized sleep (DS). Eserine sulfate induces a s
tate with the somatic and visceral signs of DS in decerebrate animals.
The rabbit and rat display diverse hemodynamic patterns during DS. 2.
To determine whether eserine sulfate provokes different responses in
the medullary raphe neuron population of these different species, the
drug (100 mg/kg, iv) was administered to urethane-anesthetized (1.2 g/
kg, iv) rabbits (1.5-3.0 kg) and rats (Wistar, 260-310 g). 3. Extracel
lular activity was recorded from 66 neurons in 30 rats. Cholinergic st
imulation provoked an increase in discharge rate (DR) in 45 neurons (6
8%), a decrease in 8 neurons (12%) and no change in 13 neurons (20%).
Recordings were obtained from 30 neurons in 11 rabbits. Stimulation of
these cells provoked an increase in DR in 17 neurons (57%), a decreas
e in DR in 7 neurons (23%) and no change in 6 neurons (20%). Interspik
e interval and auto-correlation analysis was performed on 28 rat and r
abbi t neurons. No significant difference was found between the rat an
d the rabbit with respect to the number of the neurons which were eith
er inhibited or excited by cholinergic stimulation (P > 0.05). Similar
ly, unit response to eserine was not related to whether the unit displ
ayed regular or irregular DR. 4. Therefore, we suggest that the divers
e hemodynamic patterns during DS and the distinct cardiovascular respo
nses to raphe nuclei stimulation are not due to differences in the org
anization of the raphe nuclei themselves but to differences in their a
xonal projections or in the postsynaptic receptors activated in the in
termediolateral cell column or other postsynaptic targets.