AJP - Regulatory, Integrative and Comparative Physiology, Vol 237, Issue 5 285-R290, Copyright © 1979 by American Physiological Society
Mesencephalic mechanisms for integration of female reproductive behavior in the rat
Y. Sakuma and D. W. Pfaff
Placement of bilateral electrolytic lesions in the mesencephalic central
gray (CG) of estrogen-primed ovariectomized female rats produced an
immediate decline in performance of the lordosis reflex. Lesions that
destroyed the dorsal half of the CG and the adjacent subtectal region were
effective. The decrease in individual animals in terms of the lordosis
reflex score ranged from 20 to 100% of the prelesion performance. Such
lesions abolished the facilitation of lordosis by electrical stimulation of
the ventromedial nucleus of the hypothalamus. Similar abrupt losses of
lordosis followed bilateral lesions of either a) the area between CG and
the cuneiform nucleus of the mesencephalic reticular formation (NCf); or b)
the ventrolateral quadrant of the NCf. The difference between these two
lesions was that the effect of the latter could be overridden by electrical
stimulation of the CG, whereas that of the former could not. We conclude
that the CG is an important supraspinal component of the circuit for
lordosis behavior, constituting a link between ascending somatosensory and
descending motor systems for lordosis. It probably facilitates lordosis
when activated by behaviorally relevant peripheral somatosensory and/or
ventromedial hypothalamic inputs.
