ABSTRACT
Labelled cells were found in the nucleus of the tractus solitarius (NTS) after horseradish peroxidase injections in the olfactory tubercle (OT) of the rat. These results suggest a direct pathway from the NTS to the OT. The importance of this pathway in a neural circuit related to autonomic functions is discussed.
Subject(s)
Central Nervous System/anatomy & histology , Medulla Oblongata/anatomy & histology , Olfactory Bulb/anatomy & histology , Olfactory Pathways/anatomy & histology , Animals , Horseradish Peroxidase , Male , Rats , Rats, Inbred StrainsABSTRACT
To assess the relation between the suprachiasmatic nucleus and the locus coeruleus, persistent estrous was induced in female rats by damage of the suprachiasmatic nucleus followed with electrolytic damage of the locus coeruleus. Locus coeruleus lesions resulted in a transient loss of persistent estrous indicated by sustained diestrous aspect of the vaginal smears. There was a direct correlation between duration of estrous loss and the amount of locus coeruleus damage. Simultaneous damage to the periventricular gray substance, adjacent to the locus coeruleus, prevented the suppression effects of locus coeruleus damage upon persistent estrous. These results suggest a physiological role of the locus coeruleus and periventricular gray substance in the modulation of the neuroendocrine control of ovarian function due to suprachiasmatic nucleus activity.
Subject(s)
Estrus/physiology , Locus Coeruleus/physiology , Suprachiasmatic Nucleus/physiology , Animals , Female , Locus Coeruleus/anatomy & histology , Norepinephrine/physiology , Ovary/physiology , RatsABSTRACT
To assess the relation between the suprachiasmatic nucleus and the locus coeruleus, persistent estrous was induced in female rats by exposure to constant bright light followed with electrolytic damage of the locus coeruleus. Locus coeruleus lesions resulted in a transient loss of persistent estrous indicated by sustained diestrous aspect of the vaginal smears. There was a direct correlation between duration of estrous loss and the amount of locus coeruleus damage. Simultaneous damage to the periventricular gray substance adjacent to the locus coeruleus prevented the suppression effects of locus coeruleus damage upon persistent estrous. These results suggest a physiological role of the locus coeruleus and periventricular gray substance in the modulation of the neuroendocrine control of ovarian function due to suprachiasmatic nucleus activity.
Subject(s)
Estrus/physiology , Hypothalamus/physiology , Light , Locus Coeruleus/physiology , Animals , Brain Mapping , Female , Neural Pathways/physiology , Ovary/physiology , Rats , Retina/physiology , Suprachiasmatic Nucleus/physiologyABSTRACT
The microiontophoretic administration of horseradish peroxidase (HRP) to the olfactory bulb (OB) or olfactory tubercle (OT) in cats and rats yielded similar results in both species. After an OB HRP-injection ipsilateral and contralateral labelled neurons were seen in the piriform cortex, polymorphic layer of OT, magnocellular preoptic region, lateral hypothalamus, ventromedial hypothalamic nucleus and locus coeruleus (LC). In both species more labelled structures were found after an OT HRP-injection than after an OB HRP-injection. The substantia nigra in rats was more abundantly labelled after an OT injection than after an OB one. In cats the dorsal and the ventral raphe were also labelled. In either species, OT HRP-injections resulted in a higher frequency of LC labelled neurons than after OB injections. These results favor the hypothesis that the OT plays an important role as a relay station for efferent inflow from the brain stem en route to the OB.
