Immunohistochemical Demonstration of LHRH Neurons and Their Pathways in the Rat Hypothalamus

Abstract

LHRH neurons and fiber tracts have been studied immunohistochemically in rats. After the intraventricular infusion of colchicine, a number of immunoreactive LHRH neurons were consistently evident in the preoptico-septal area and in the diagonal band of Broca. The immunoreactive fiber tracts originating in those areas were classified into two groups: preoptico-terminal and preoptico-infundibular tracts. The former terminated in the OVLT. The latter was further divided into the mediobasal and laterobasal tracts; both were found to terminate in the median eminence. The mediobasal tract ran posteriorly through the ventral portion of the lateral periventricular area. The laterobasal tract ran posteriorly in the medial forebrain bundle and was accompanied by several immunoreactive neurons. The immunoreactive cell bodies were further scattered in the base of the tuberal hypothalamic area. An anterior bilateral Halász cut in the retrochiasmatic region was followed by a great reduction of the immunoreactive materials in the median eminence and by the appearance of the immunoreactive perikarya in the preoptico-septal area and in the diagonal band of Broca. A horizontal hypothalamic cut, on the other hand, which disconnected the tubero-infundibular tract between the median eminence and the arcuate nuclei, caused neither reduction of the immunoreactive materials in the median eminence nor appearance of the immunoreactive perikarya in the arcuate nuclei. Those results indicate that the bulk of the immunoreactive LHRH is synthesized in the anterior hypothalamic area and transported by the preoptico-terminal and -infundibular tracts but a minor part is produced in the cell bodies located in the basal tuberal hypothalamus and transported to the median eminence.

Roles of .GAMMA.-aminobutyric acid and serotonin in the arcuate nucleus in the control of prolactin and luteinizing hormone secretion.

“…We have recently shown that GABA inhibited spontaneous activity of most of the ARC neurons (NISHIHARA et a1.,1986). Since rat ARC is poor in LHreleasing hormone (LHRH) cell bodies (KAWANO and DAIKOKU, 1981), the inhibitory action of GABA on LH secretion might be mediated by ARC neurons other than LHRH neurons. It has been reported that injection of relatively large doses of GABA…”

The LHRH neuronal system in female rats: Relation to the medial preoptic nucleus.

“…Since the MPN is located adjacent to the OVLT where the cell bodies and fibers containing LHRH are reported to be concentrated (Setalo et al, 1976 ;Ibata et al, 1979 ;Kawano and Daikoku, 1981 ;Hoffman and Gibbs, 1982 ;King et al, 1982 ;Shivers Endocrinol. Japon.…”

Intercellular Communication within the Rat Anterior Pituitary: Immunohistochemical Study on the Relationship between the Hypothalamus, Agranular Cells and GnRH Neurons in the Pars Tuberalis and Anterior Pituitary Gland

“…Previous research has alluded to the distribution or projection of the LH-RH neurons in the brain [12,14,43]. Kawano and Daikoku [12] studied the distribution of LH-RH neurons in the diencephalon, and proposed two distinct pathways in the rat brain. One is a mediobasal pathway originating from the preoptic area, which runs straight down the sagittal center of the basal layer of the third ventricle.…”