It is well established that mast cells (MCs) occur within the CNS of many species. Furthermore, their numbers can increase rapidly in adults in response to altered physiological conditions. In this study we found that early postpartum rats had significantly more mast cells in the thalamus than virgin controls. Evidence from semithin sections from these females suggested that mast cells were transiting across the medium-sized blood vessels. We hypothesized that the increases in mast cell number were caused by their migration into the neural parenchyma. To this end, we purified rat peritoneal mast cells, labeled them with the vital dyes PKH26 or CellTracker Green, and injected them into host animals. One hour after injection, dye-filled cells, containing either histamine or serotonin (mediators stored in mast cells), were located close to thalamic blood vessels. Injected cells represented approximately 2-20% of the total mast cell population in this brain region. Scanning confocal microscopy confirmed that the biogenic amine and the vital dye occurred in the same cell. To determine whether the donor mast cells were within the blood-brain barrier, we studied the localization of dye-marked donor cells and either Factor VIII, a component of endothelial basal laminae, or glial fibrillary acidic protein, the intermediate filament found in astrocytes. Serial section reconstructions of confocal images demonstrated that the mast cells were deep to the basal lamina, in nests of glial processes. This is the first demonstration that mast cells can rapidly penetrate brain blood vessels, and this may account for the rapid increases in mast cell populations after physiological manipulations.
Background and Purpose-Perinatal hypoxia-ischemia (HI) produces acute and prolonged inflammation of the brain.Mast cells (MCs), numerous in the pia and CNS of neonatal rats, can initiate inflammation attributable to preformed mediators. MCs contribute to HI brain damage in the neonatal rat; MC stabilization protects through 48 hours of reperfusion. Here we hypothesize that HI induces early MC migration, activation, and release of proinflammatory molecules. Methods-HI
Male hamsters were maintained on long (14 h light : 10 h darkness; 14L : 10D) or short (6L : 18D) photoperiods. Animals on short-days had reduced levels of LH in the serum and anterior pituitary gland, decreased androgen in the circulation and regressed testes and accessory sex organs. These same hamsters had significantly raised concentrations of hypothalamic luteinizing hormone releasing hormone (LH-RH). There was no significant difference in the response to exogenous LH-RH between groups maintained on long- and short-days. Castration significantly reduced levels of LH-RH in the hypothalamus in the long-day animals but had little effect on this parameter in short-day animals which had already undergone testicular regression. The increased levels of LH-RH in the hyothalami of both intact and castrated hamsters on non-stimulatory photoperiods is interpreted as a decreased release of the neurohormone which subsequently results in a decreased release of LH.
Immunoreactive LHRH-like material has been found in the cells and fibers of the nervus terminalis in fetal and adult guinea pig brains. LHRH-containing neurons and axons are seen in the nasal mucosa intermingled with fibers of the olfactory nerves, in ganglia along the ventromedial surfaces of the olfactory bulbs and forebrain, and in clusters surrounding perforating branches of the anterior cerebral artery in the regions of the septal nuclei and olfactory tubercle. Nonreactive neurons are found adjacent to the LHRH-positive cells in all of the ganglia. LHRH-immunoreactive cells and axons of the nervus terminalis are in intimate contact with cerebral blood vessels and the cerebrospinal fluid along the intracranial course of this nerve, deep to the meninges. The possible involvement of these structures in the neural mechanisms of sexual behavior and the neurohormonal regulation of reproductive function are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.