AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 2 214-R218, Copyright © 1985 by American Physiological Society
Subfornical organ and supraoptic nucleus connections with septal neurons in rats
A. V. Ferguson, C. W. Bourque and L. P. Renaud
Extracellular single unit recordings obtained in pentobarbital-anesthetized
male Sprague Dawley rats were utilized to examine the electrophysiology of
connections of medial septum-diagonal band of Broca (MS-DBB) neurons with
the subfornical organ (SFO), hippocampal commissure (HC), and supraoptic
nucleus (SON). Of the 119/216 cells tested that demonstrated antidromic
activation from SON, many (60%) were orthodromically excited by SFO
stimulation, whereas most (68%) were unresponsive to stimulation in the
adjacent HC. Separate populations of MS-DBB neurons that displayed
antidromic activation from the SFO (11/140 cells tested) or HC (24/78
tested) were orthodromically excited by SON stimulation. Three cells were
activated antidromically from both the SFO and SON. These observations
reveal some possible interconnections between these three brain regions and
point to the existence of an indirect pathway whereby the SFO can influence
SON neurons through an influence on MS-DBB neurons.
