The Journal of Neuroscience, October 15, 2000, 20(20):7722-7727
Estrous Changes in Responses of Rat Gracile Nucleus Neurons to
Stimulation of Skin and Pelvic Viscera
Heather B.
Bradshaw and
Karen J.
Berkley
Program in Neuroscience, Florida State University, Tallahassee,
Florida 32306-1270
Multi- and single-unit recording was performed in the gracile
nucleus in urethane-anesthetized rats to examine estrous variations in
responses of its neurons to brushing the hindquarters and mechanical stimulation of the uterus, vaginal canal, cervix, and colon. Six rats
each were studied in each of the four estrous stages: proestrus (P),
estrus (E), metestrus (M), and diestrus (D). The magnitude of
multi-unit responses to gentle brushing of the perineum, hip, and tail,
but not the foot and leg, was significantly greater during proestrus
than during other stages. Of 70 single units responsive to brush, 56 (80%) responded to stimulation of at least one viscus. Although this
percentage did not change with estrous stage, the direction and latency
of some responses did. Pressure on the cervix evoked significantly more
inhibitory (vs excitatory) responses in P than in E and M, and the
response latency was significantly longer in D and P than in E and M. The direction of response to vaginal distention did not change with
estrous stage, but response latency was significantly longer in D than
in P and E. Uterine distention evoked significantly more inhibitory
responses in D than in P, with no estrous changes in latency. Responses
to colon distention did not change. These variations in both magnitude of response to tactile stimulation and characteristics of response to
stimulation of reproductive organs, but not the colon, correlate with
changes in mating behaviors of the female rat, suggesting that the
gracile nucleus is a component of neural systems that control
reproductive behaviors.
Key words:
female; dorsal column; reproduction; plasticity; somatosensory; pain
Copyright © 2000 Society for Neuroscience 0270-6474/00/20207722-06$05.00/0
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