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  • 1
    Electronic Resource
    Electronic Resource
    Single unit recordings in the rat pineal gland: Evidence for habenulo-pineal neural connections (1980)
    Springer
    Experimental brain research 39 (1980), S. 187-192 
    Details
    ISSN: 1432-1106
    Keywords: Pineal ; Single unit recording ; Habenula stimulation ; Habenulo-pineal pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Extracellular potentials were recorded in the pineal gland of urethane-anesthetized rats. Two distinct populations of excitable pineal “cells” were found, the silent “cells” which were driven by habenula stimulation and the spontaneously active cells. In the former case 17 of the responses (median latency of 1.2 ms) showed a positive-negative potential, and 6 (about 1 ms latency) showed only positive potential of 1–2 ms duration. The remaining cells (114), which could not be driven by habenula stimulation, exhibited spontaneous activity with a firing frequency from less than 1 Hz to greater than 100 Hz with a median firing frequency of 10 Hz. These experiments clearly demonstrate a direct habenulo-pineal fiber pathway and furthermore show that there are neuronal elements in the pineal which are only activated by habenula stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237549
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    In vivo GABA release from the medial preoptic area of diestrous and ovariectomized rats (1982)
    Springer
    Experimental brain research 46 (1982), S. 69-72 
    Details
    ISSN: 1432-1106
    Keywords: GABA ; Push-pull ; LH ; Preoptic area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The push-pull cannula technique was used to examine the endogenous release of GABA from the medial preoptic area (MPO) of unanesthetized rats. In diestrous females the mean resting release of GABA was 27.1±2.0 pmol/min. GABA release was significantly elevated by increasing the potassium concentration in the perfusion solution to 50 mM, whereas it was dramatically inhibited by mercaptoproprionic acid (1.0 mM), a glutamic acid decarboxylase inhibitor. A comparison between diestrous females and chronically castrated animals indicated that endogenous GABA release in OVX animals was only 60–70% of that in diestrous animals. A model for the presynaptic inhibition of NE by estrogen receptive GABAergic neurons in the MPO is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238099
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Involvement of preoptic-anterior hypothalamic GABA neurons in the regulation of pituitary LH and prolactin release (1983)
    Springer
    Experimental brain research 52 (1983), S. 356-362 
    Details
    ISSN: 1432-1106
    Keywords: Preoptic ; anterior hypothalamic area ; GABA ; Muscimol ; Norepinephrine turnover ; LH ; Prolactin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of intraventricular injections of the highly specific gamma-amino-butyric acid (GABA) agonist muscimol (5 nmol/animal) on blood LH and prolactin levels were measured in ovariectomized (ovx) and in ovx estrogen-progesterone (OEP) primed rats. While the drug stimulated pituitary prolactin release in both experimental groups, pituitary LH release was significantly inhibited in the ovx animals. Muscimol was without any effect on LH levels in ovx-OEP primed rats. Bilateral implantation of tubes containing a muscimol-mannitol mixture into the medial preoptic/ anterior hypothalamic (MPO/AH) area abolished pulsatile LH release whereas blood prolactin values were elevated. The intraventricular injection of GABA (8 μmol) also reduced LH and increased prolactin levels in the blood. Measurements of catecholamine turnover rates in the MPO/AH and in the mediobasal hypothalamus (MBH) yielded reduced preoptic but unchanged hypothalamic norepinephrine (NE) and stimulated hypothalamic dopamine (DA) turnover. In view of the well known stimulatory involvement of the NE system in the mechanism of pulsatile LH release and the inhibitory effect of GABA and its agonist muscimol on pulsatile LH release, it is suggested that GABA inhibits NE release in the MPO/AH by the mechanism of presynaptic inhibition. The observation that muscimol is unable to suppress LH release in vox OEP-primed rats may indicate that those estrogen receptive neurons in the MPO/AH which mediate the negative feedback action of the steroid may use GABA as neurotransmitter and that they are the neurons which inhibit NE release. The inhibitory effect of locally implanted muscimol into the MPO/AH also supports this hypothesis. The facilitatory action of this implanted GABAergic drug on prolactin release points to the involvement of control mechanisms for the regulation of prolactin secretion which reside in the MPO/ AH. The stimulatory effect of intraventricularly injected GABA on hypothalamic DA turnover makes it likely that other than dopaminergic mechanisms are involved in mediating the stimulatory effect of GABA on prolactin release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238029
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Hyperpolarization of hypothalamic parvocellular neurons by 17 β-estradiol and their identification through intracellular staining with procion yellow (1980)
    Springer
    Experimental brain research 40 (1980), S. 440-447 
    Details
    ISSN: 1432-1106
    Keywords: Parvocellular neurons ; Intracellular recordings ; Procion yellow ; Estrogen ; Humoral control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intracellular recordings and injections of procion yellow (PY) were made in parvocellular neurons in hypothalamic slices of female guinea pigs. Eighty-five neurons, with an average resting membrane potential of -35 mV, were recorded in the arcuate (ARC) ventromedial (VM), and in the cellpoor zones between the ARC and VM. Eleven of the ARC neurons and four neurons from the cell-poor zone could be driven antidromically by median eminence (ME) stimulation, nine other neurons from the three areas could be driven orthodromically by stria terminalis (ST) stimulation. Twenty-eight parvocellular neurons were tested with 17 β-estradiol (E2), which was applied in the bathing medium as the free steroid. Eleven neurons (nine ARC and two cell-poor-zone neurons) were hyperpolarized 2 to 24 mV by 10−10 M E2 concentrations. 10−8 M estrone concentration was without effect on three of these cells. Through the intracellular injection of PY, the estrogen-sensitive neurons (N = 11) were identified as small fusiform cells with few dendrites. Spine-like appendages were found on only one of these cells. None of the larger pyramidal-like neurons of these areas responded to the application of E2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236152
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    In vivo release of neurotransmitters in the medial basal hypothalamus of the monkey (1984)
    Springer
    Experimental brain research 54 (1984), S. 575-578 
    Details
    ISSN: 1432-1106
    Keywords: Push-pull cannula ; Hypothalamus ; Neurotransmitters ; LH ; Prolactin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In vivo release rates of norepinephrine (NE), epinephrine (E), dopamine (DA), gammaaminobutyric acid (GABA), glutamate (GLU) and beta-endorphin (βE) in the medial basal hypothalamus (MBH) of unanaesthetized female macaca fascicularis monkey, and the effects thereon of estrogen (E2) treatment, have been estimated using pushpull perfusion methodology. DA, NE, E, GABA, GLU and βE were all detectable in 30 min perfusate fractions. No direct correlation between their release rates and those of LH and PRL could be observed. E2 induced an initial decrease, then an increase, in LH and PRL secretion, and concomitant changes in the release patterns of DA, NE, E. GABA and GLU were apparent. This study demonstrates that in vivo push-pull perfusion methodology may be applied to the unanaesthetized monkey, and when combined with venous catheterization for serial blood sampling may prove to be a powerful tool in the investigation of the central molecular events governing neuroendocrine functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235484
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    Paper (German National Licenses)
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