A substance P projection from the VMH to the dorsal midbrain central gray: implication for lordosis.
Substance P has been implicated in the modulation of lordosis behavior at the level of the dorsal midbrain central gray (dMCG). Bilateral injections of substance P into the dMCG facilitate estrogen-induced lordosis behavior in ovariectomized female rats. Input from the ventromedial nucleus of the hypothalamus (VMH) to the dMCG is a vital link in the central nervous system control that mediates the expression of lordosis behavior. Substance P-containing cells have been localized in the VMH and substance P binding sites are localized in the dMCG; this suggested to us that substance P neurons originating in the VMH may terminate in the dMCG. The present study examined the projection of substance P-immunoreactive neurons (SP-IR) in the VMH to the dMCG. The present study examined the projection of substance P-immunoreactive neurons (SP-IR) in the VMH to the dMCG. The retrograde tract tracer fluorogold revealed cell bodies throughout the extent of the VMH and sP immunofluorescence labelled a subpopulation of these cells particularly in the ventrolateral part of the VMH. The majority of sP-projection cells was localized in the caudal two-thirds of the VMH. Thirteen percent of the sP-IR cells were observed to project to the dMCG, while approximately 17% of the sP-IR cells of the ventrolateral part of the VMH projected to the dMCG. These results provide morphological evidence for a substance P projection from the VMH to an area where substance P has been demonstrated to facilitate lordosis behavior.(ABSTRACT TRUNCATED AT 250 WORDS)
Dornan
W A
WA
Department of Anatomy and Cell Biology, U.C.L.A. School of Medicine 90024.
Akesson
T R
TR
Micevych
P E
PE
D000818:Animals; D005260:Female; D005455:Fluorescent Antibody Technique; D008636:Mesencephalon / Q000737:chemistry / Q000502:physiology*; D009434:Neural Pathways / Q000737:chemistry / Q000502:physiology; D051381:Rats; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013373:Substance P / Q000032:analysis / Q000502:physiology*; D014697:Ventromedial Hypothalamic Nucleus / Q000737:chemistry / Q000502:physiology*
D013373:Substance P