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Estrogen receptor‐alpha immunoreactive neurons in the ventrolateral periaqueductal gray receive monosynaptic input from the lumbosacral cord in the rhesus monkey
Author(s) -
Vanderhorst Veronique G.J.M.,
Terasawa Ei,
Ralston Henry J.
Publication year - 2001
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.10098
Subject(s) - periaqueductal gray , neuroscience , spinal cord , lumbosacral joint , biology , anatomy , retrograde tracing , alpha (finance) , central nervous system , midbrain , medicine , construct validity , nursing , patient satisfaction
Estrogen affects female sexual behavior, analgesia, and micturition in mammals. One of the possible sites at which estrogen might exert its effect on these functions is the periaqueductal gray (PAG). The PAG is involved in each of these functions, it receives sensory input relevant to these functions from the lumbosacral cord, and contains estrogen receptor‐alpha immunoreactive (ER‐α IR) neurons. The present light (LM) and electron microscopic (EM) study seeks to determine whether there are monosynaptic projections from the lumbosacral cord to ER‐α IR neurons in the PAG of the female rhesus monkey. Tracer was injected into the lumbosacral cord to visualize the lumbosacral‐PAG projection, and the distribution of ER‐α IR neurons in the PAG was studied immunohistochemically. The medial part of the ventrolateral caudal PAG received the densest projection from the lumbosacral cord. Another prominent projection was found in the lateral PAG at the intercollicular level. Although ER‐α IR neurons were widely distributed throughout the PAG, approximately 40% of ER‐α IR PAG neurons were located as a distinct cluster in the medial portion of the ventrolateral, caudal PAG. Double labeling experiments showed that the location of this cluster precisely overlapped with the densest lumbosacral‐PAG projection. EM revealed that axons from the lumbosacral cord made asymmetrical synaptic contacts with unlabeled dendrites and ER‐α IR neuronal somata in the ventrolateral PAG. It is concluded that there exists a specific, monosynaptic pathway from lumbosacral neurons to ER‐α expressing PAG neurons in the rhesus monkey. This pathway might be involved in the mechanisms of analgesia, blood pressure, mating behavior, and micturition. J. Comp. Neurol. 443:27–42, 2002. © 2002 Wiley‐Liss, Inc.