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The sexually dimorphic output of the suprachiasmatic nucleus
Abstract
This study investigated the origin of vasopressin-immunoreactive (AVP-ir) fibers in the medial preoptic area (MPOA) in the gerbil hypothalamus. The MPOA contains a sexually dimorphic area (SDA) that has a subgroup of cells--the SDA pars compacta (SDApc)--which is absent in females in Nissl-stained preparations. It was previously found that AVP-ir fibers were clustered in a sexually dimorphic manner in the region that houses the SDApc in males: the clusters were much larger in males than in females. This study tried to determine whether these AVP-ir fibers came from the AVP cell bodies in the bed nucleus of the stria terminalis (BST), whose efferents to the SDA are sexually dimorphic, or from the suprachiasmatic nucleus (SCN). Animals in one group received cuts dorsolateral to the SDA and ventromedial to the BST, which would transect efferents from the BST. A second group of animals received cuts ventral to the SDA and immediately dorsal to the SCN, which would transect efferents from the SCN. Cuts dorsal to the SCN eliminated AVP-ir fibers to the medial SDA (mSDA) and the SDApc, whereas cuts ventromedial to the BST and dorsolateral to the SDA left intact the AVP-ir innervation of the MPOA. These results suggests that the mSDA and the SDApc receive their innervation from the SCN. In a second experiment, the retrograde tracer fluorogold was injected into the area of the SDApc of gerbils and stained sections of their brains immunocytochemically for AVP. These injections labeled AVP-ir cells in the SCN but not in the medial amygdaloid nucleus or the BST. These double-labeled cells confirm that the SCN is the most likely source of the sexually dimorphic AVP innervation of the SDA. The existence of a pathway from the SCN to the SDA might provide a neural substrate by which the SCN can organize reproductive processes into temporal patterns.
Subject Area
Neurosciences|Clinical psychology|Psychobiology
Recommended Citation
Crenshaw, Bradley John, "The sexually dimorphic output of the suprachiasmatic nucleus" (1993). Doctoral Dissertations Available from Proquest. AAI9316635.
https://scholarworks.umass.edu/dissertations/AAI9316635