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NMDA receptor-mediated long term modulation of electrically evoked field potentials in the rat medial vestibular nuclei (1992)

Capocchi, G. ; Torre, G. Della ; Grassi, S. ; [et al.]

Springer

Experimental brain research 90 (1992), S. 546-550

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ISSN: 1432-1106

Keywords: Medial vestibular nuclei ; Potentiation ; Depression ; AP5 ; Rat

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary The effect of high frequency stimulation (HFS) of the primary vestibular afferents on field potentials recorded in the ipsilateral Medial Vestibular Nuclei (MVN) was studied. Our results show that potentiation and depression can be induced in different portions of MVN, which are distinguishable by their anatomical organization. HFS induces potentiation of the monosynaptic component in the ventral portion of the MVN, whereas it provokes depression of the polysynaptic component in the dorsal portion of the same nucleus. The induction of both potentiation and depression was blocked under AP5 perfusion, thus demonstrating that NMDA receptor activation mediates both phenomena. Furthermore, the finding that the field potentials were not modified during perfusion with DL-AP5, as previously reported, supports the hypothesis that NMDA receptors are not involved in the normal synaptic transmission from the primary vestibular afferent fibres, but are only activated following hyperstimulation of this afferent system. Our results suggest that the mechanisms of long term modification of synaptic efficacy observed in MVN may underlie the plasticity phenomena occurring in vestibular nuclei.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00230937

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Cyclic nucleotides and haemoglobin concentration in rabbit bone marrow cell suspensions stimulated by purified erythropoietin (1984)

Fanò, G. ; Menchetti, G. ; Secca, T. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Cell Biochemistry and Function 2 (1984), S. 119-124

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ISSN: 0263-6484

Keywords: Bones ; bone marrow ; cAMP ; cGMP ; erythropoietin ; Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: This study was conducted to determine the possible correlations between cyclic nucleotides cyclic adenosine monophosphate (cAMP) and cyclic guanine monophosphate (cGMP), and haemoglobin (Hb) concentration in nucleated cell suspensions of rabbit bone marrow incubated with erythropoietin (Ep). The levels of cAMP and cGMP were measured following the addition of different Ep concentrations to the suspensions. The Hb concentration was also measured in suspensions treated with Ep, dibutyryl cAMP (db-cAMP) or dibutyryl cGMP (db-cGMP), respectively. The following results were obtained: (1) upon the addition of 1 IU ml-1 Ep, an increase of cAMP levels was related to an increase in Hb concentration; while a decrease of Hb concentration was related to an increase of cGMP levels obtained when 0.1 IU ml-1 Ep was present in the incubation mixture. (2) A mimetic effect on Hb concentration was obtained upon the addition of db-cAMP or db-cGMP to the suspensions. (3) A quantitative correlation was found between the cAMP/cGMP ratio and Hb levels in cellular suspensions. This rapport was reviewed with respect to the controls as a decrease in Hb concentration when the ratio is less than one and an increase in Hb concentration when the ratio is greater than one.

Additional Material: 7 Ill.