Disease relevance of Median Eminence

• Blockade of TGF-alpha action in the median eminence, a site of glial-LHRH nerve terminal association, delayed puberty [1].
• Obesity on a high-fat diet: role of hypothalamic galanin in neurons of the anterior paraventricular nucleus projecting to the median eminence [2].
• Concomitant secretion of adrenocorticotropin, beta-endorphin, and gamma-melanotropin from perfused pituitary tumor cells of Cushing's disease: effects of lysine vasopressin, rat median eminence extracts, thyrotropin-releasing hormone, and luteinizing hormone-releasing hormone [3].
• Addition of rat median eminence extract significantly stimulated ACTH secretion and increased levels of intracellular cAMP in both cell preparations, and a dose-response relationship appeared to exist between the dose of rat median eminence extract added and either ACTH secretion or intracellular cAMP formation in the thymic tumor cells [4].
• The present study examined whether hyperprolactinemia also increases local cerebral glucose utilization, as determined by the 2-deoxy-D-[1-14C]glucose method, in the median eminence and other brain structures [5].

Psychiatry related information on Median Eminence

• The median eminence content of pGlu-His-Pro-Gly (TRH-Gly, a presumed immediate precursor of TRH), proTRH160-169 or TRH were not affected by food deprivation [6].
• Water deprivation had no effect on DOPAC concentrations in the neural lobe, intermediate lobe or median eminence, but increased DA concentrations in the neural lobe [7].
• Using the pregnant mare serum (PMS) model of induced ovulation and an in vitro uptake system, serotonergic activity reached peak values (p = 0.01) in the suprachiasmatic nuclear region (SNR) and median eminence (ME) (p = 0.007) during the critical period for luteinizing hormone release [8].

High impact information on Median Eminence

• The median eminence of the pituitary is rich in opioid receptors, and exogenous opioids have major effects on the release of adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), prolactin, growth hormone (GH) and thyrotropin [9].
• Vasopressin (arginine vasopressin, AVP) is present in two types of nerve fibres in the median eminence (ME) [10].
• Magnocellular axons in passage through the median eminence release vasopressin [10].
• We report here that a substance recognized by this antibody is present in GnRH-containing neurones of the rat brain and appears to coexist with GnRH in secretory granules of nerve terminals in the median eminence [11].
• Co-localization of corticotropin-releasing factor and vasopressin in median eminence neurosecretory vesicles [12].

Chemical compound and disease context of Median Eminence

• Characterization of in vitro dopamine synthesis in the median eminence of rats with haloperidol-induced hyperprolactinemia and bromocriptine-induced hypoprolactinemia [13].
• Hypoglycemia enhances turnover of corticotropin-releasing factor and of vasopressin in the zona externa of the rat median eminence [14].
• Chronic fluoxetine treatment significantly attenuated the anorexia and body weight loss, as well as the depletion of CRH-41 from the median eminence and the elevation in serum corticosterone levels induced by LPS [15].
• Haloperidol-induced hyperprolactinemia also caused a delayed (at 6 and 12 h) increase in median eminence DOPAC concentrations in these animals which was blocked by PRL-AB [16].
• The effect of chronic hyperprolactinemia was studied on (a) GABA concentration in the pituitary anterior lobe; (b) GABA biosynthesis enzyme, glutamate decarboxylase (GAD) activity in the hypothalamic median eminence, and (c) GABA degradation enzyme GABA-transaminase (GABA-T) activity at both levels [17].

Biological context of Median Eminence

• The tight link between GAL and LHRH neuronal systems is strengthened by the observation that during the estrous cycle of the rat, rGAL and LHRH contents in the median eminence show an identical profile (r = 1.00) [18].
• Our previous studies have shown that stimulation of the anteroventral third ventricle (AV3V) region of the brain increases atrial natriuretic peptide (ANP) release, whereas lesions of the AV3V region or median eminence of the tuber cinereum block the release of ANP caused by blood volume expansion [19].
• The presence of putative melatonin receptors in the suprachiasmatic nuclei and median eminence of these rodent species suggests that these brain regions are important loci for melatonin effects on circadian rhythms and reproduction [20].
• The mRNA encoding vasopressin has recently been documented within the magnocellular hypothalamo-neurohypophyseal projections of the rat such as the median eminence (ME) and the posterior pituitary (PP), suggesting the possibility of its axonal transport [21].
• The six classic phenotypes were identified in histological sections with rabbit antisera to neurotransmitters (or related enzymes), nuclear bromodeoxyuridine was detected with a mouse monoclonal antibody, and an axonal projection to the median eminence was determined with the fluorescent retrograde tracer fast blue [22].

Anatomical context of Median Eminence

• These results show that the arcuate nucleus is the origin of the GRF-containing fibres that project to the median eminence and establish the MSG-treated rat as an in vivo model for studying growth hormone secretion in the absence of neurohumoral GRF [23].
• Parvocellular cell bodies in the paraventricular nucleus (PVN) which project to the external zone of the median eminence can be stained for both CRF and VP after adrenalectomy, and there is light microscopic immunocytochemical evidence that neurophysin (NP) may be located within some of the CRF-containing axons [12].
• The medial preoptic and hypothalamic areas, including the median eminence, contain noradrenaline-containing terminals which originate from discrete noradrenaline-containing cell groups in the lower brain stem [24].
• However, in contrast to the findings for TRH, no staining was observed in axon terminals of the median eminence [25].
• Depolarization- and ionophore-induced release of octacosa somatostatin from stalk median eminence synaptosomes [26].

Associations of Median Eminence with chemical compounds

• It is produced by hypothalamic neurones, secreted in a pulsatile manner into the capillary plexus of the median eminence and effects the release of luteinizing hormone and follicle stimulating hormone from gonadotropic cells in the anterior pituitary [27].
• MSG treatment results in the complete loss of GRF-immunoreactive cell bodies within this nucleus and provokes a selective disappearance of GRF-immunoreactive fibres in the median eminence [23].
• Gonadotropin-releasing hormone and dopamine were identified simultaneously in the same block of tissue from the median eminence of the rat brain [28].
• AMPA and kainate appear to act primarily at the arcuate nucleus/median eminence, the site of GnRH nerve terminals [29].
• Enkephalins, SP, angiotensin II, and cholecystokinin-like immunoreactivity are also found in nerve terminals in the external layer of the median eminence of some species [30].

Gene context of Median Eminence

• This may reflect lateralized hypothalamic and/or suprahypothalamic function resulting in CRH-responsive lateralized secretion of AVP from parvocellular and/or magnocellular axons in the median eminence and the posterior pituitary [31].
• Exogenous administration of leptin to fasted animals restored PC1 levels in the median eminence (ME) and the PVN to approximately the level found in fed control animals [32].
• CRF receptor expression in hypothalamic neurosecretory structures, including the paraventricular nucleus and median eminence, is generally low [33].
• Moreover, B or T MPOA implants also decreased resting-state levels of AVP but not CRH in the median eminence, and these effects were correlated with ACTH responses to restraint [34].
• Infundibular nucleus (including median eminence) NPY ICC staining or mRNA expression, and AGRP ICC staining, increased with premorbid illness duration [35].

Analytical, diagnostic and therapeutic context of Median Eminence

• We demonstrate in this report, using post-embedding electron microscopic immunocytochemistry on serial ultrathin sections, that CRF, VP and NP-VP are contained not only in the same axons and terminals, but in the same 100-nm NSVs in the median eminence of both normal and adrenalectomized rats [12].
• Radioimmunoassay determinations indicated in vitro biosynthesis of leukotriene C4 in most regions of the brain, with the highest levels obtained in the hypothalamus and the median eminence [36].
• Finally, using the indirect immunofluorescence technique, nerve endings in the median eminence and cell bodies in the preoptic area reacting with antibodies raised against leukotriene C4 were observed [36].
• The addition of lysine vasopressin and rat median eminence extracts (MEE) to the perfusion system concomitantly enhanced the release of ACTH-LI, beta-EP-LI, and gamma-MSH-LI, although the dose-response relationship was clear-cut only in the case of MEE [3].
• Immediate release of prolactin and biphasic effects on growth hormone release following electrical stimulation of the median eminence [37].

References