AJP - Regulatory, Integrative and Comparative Physiology, Vol 269, Issue 2 236-R244, Copyright © 1995 by American Physiological Society
A long-lasting change in the excitability of fetal brain neurons following activation of dam's hypothalamus in rats
S. Nakamura, S. Arakawa and S. Nishiike
Department of Physiology, Faculty of Medicine, Kanazawa University, Japan.
The influence of the dam's brain on the electrical activity of brain
neurons was examined in the rat fetus while the fetus was still connected
to the dam by the umbilical cord. Under urethan anesthesia, the spontaneous
or glutamate-induced discharge of single brain stem neurons in fetuses was
decreased by electrical stimulation of the dam's hypothalamus (Hyp). The
changes occurred 21-122 s after start of the stimulation and persisted
throughout the recording until the cells were lost after 2.4-9.5 min. The
effects of electrical stimulation of dam's midbrain reticular formation
(MRF) were much weaker and of shorter duration compared with Hyp
stimulation. The dam's blood pressure was increased immediately after the
beginning of MRF or Hyp stimulation. The change was always greater with MRF
than with Hyp stimulation. Activation of the dam's MRF and Hyp had no
marked influence on the blood flow in the fetal brain. These results
indicate the presence of a functional interaction between the brain of the
dam and that of its fetus mediated through the placenta.
