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- Diaz-Cabiale, Z., et al.
(författare)
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Long-term modulation by postnatal oxytocin of the α2-adrenoceptor agonist binding sites in central autonomic regions and the role of prenatal stress
- 2004
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Ingår i: Journal of neuroendocrinology (Print). - : Wiley. - 0953-8194 .- 1365-2826. ; 16:3, s. 183-190
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to evaluate whether oxytocin administered in male rats subcutaneously early in life in the absence or presence of food restriction during pregnancy has life-long effects on the α2-agonist binding sites in the nucleus of the solitarii tract (NTS), in the hypothalamus and the amygdala, as evaluated by quantitative receptor autoradiography. Maternal food restriction alone increased the affinity of the α2-agonist [3H]UK14.304 binding sites exclusively in the NTS. In offspring from ad libitum fed dams, oxytocin treatment significantly increased the density of α2-agonist binding sites in the NTS and in the hypothalamus. The Kd value of the α2-agonist binding sites in the hypothalamus of these rats, but not in the other regions studied, was also significantly increased. In offspring from food-restricted dams, oxytocin treatment produced a significant increase of the Bmax values in the hypothalamus and the amygdala and the Kd value of the α2-agonist binding sites in the NTS of these rats also was selectively and significantly increased. These results suggest that a postnatal, oxytocin-induced increase of regional α2-adrenoceptor function can be seen in adulthood by a persistent, regionally selective increase in the density of central α2-adrenoceptor agonist binding sites, in the absence of an affinity change in the NTS. Such a regional increase of α2-adrenoceptor signalling in adulthood may contribute to the anti-stress action of postnatal oxytocin. By contrast, after prenatal stress, the potential increase in α2-adrenoceptor signalling takes place via selective increases of density with no changes of affinity of the α2-agonist binding sites in the hypothalamus and the amygdala.
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- Diaz-Cabiale, Z, et al.
(författare)
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Oxytocin/alpha(2)-Adrenoceptor interactions in feeding responses
- 2000
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Ingår i: Neuroendocrinology. - : S. Karger AG. - 0028-3835 .- 1423-0194. ; 71:3, s. 209-218
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Tidskriftsartikel (refereegranskat)abstract
- The modulation of α<sub>2</sub>-adrenoceptor-induced food intake by oxytocin has been evaluated in studies on food intake and by quantitative receptor autoradiography in the hypothalamus and the amygdala of the rat. The effects of lateral intracerebroventricular administration of clonidine and oxytocin were evaluated on food intake in satiated animals. Food consumption was measured at 30, 90, 240 min and 22 h (1,320 min) after injection. The coinjection of oxytocin and clonidine was found to counteract the increase in food intake produced by clonidine (p < 0.001) in satiated rats. Receptor autoradiographic experiments showed that oxytocin significantly increased the K<sub>d</sub> values of [<sup>3</sup>H]<i>p</i>-aminoclonidine α<sub>2</sub>-agonist-binding sites in the hypothalamus. Effective oxytocin concentrations ranged between 0.3 and 1 n<i>M</i> (p < 0.05) with a maximal action of 250% at 1 n<i>M</i>. The B<sub>max</sub> value was significantly increased (p < 0.05) for all concentrations of oxytocin. In the amygdala, oxytocin also increased both the K<sub>d</sub> of [<sup>3</sup>H]<i>p</i>-aminoclonidine-binding sites by about 190% at 1 n<i>M</i> and the B<sub>max</sub> values at 1 and 3 n<i>M</i> (p < 0.05). Oxytocin (1 n<i>M</i>) also significantly and substantially (p < 0.01) increased the K<sub>d</sub> and B<sub>max</sub> values of the [<sup>3</sup>H]UK 14.304 α<sub>2</sub>-agonist-binding sites in the hypothalamus and amygdala in agreement with the results obtained with the other agonist of the α<sub>2</sub>-adrenoceptor [<sup>3</sup>H]<i>p</i>-aminoclonidine. This effect was partially blocked by the presence of the specific oxytocin receptor antagonist, CAP. These findings suggest the existence of an antagonistic oxytocin/α<sub>2</sub>-receptor interaction in the hypothalamus and amygdala that may be of relevance for the demonstrated modulation of α<sub>2</sub>-adrenoceptor-induced feeding responses by oxytocin.
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