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The aim of the research was to monitor the influence of neonatal thymectomy on the reactivity of chicken spleen structures. The investigations were carried out on chickens with the thymus removed on the 1st day after hatching and with antigen administered in the form of sheep erythrocytes (SRBC) at the age of 12 weeks. On days 6, 14 and 21 after antigen administration the spleen was taken out and histological slides were prepared. On the established area of HE slides germinal centres were counted and mature centres of type I and immature ones of type II were distinguished. Reaction to the acid phosphatase (APh) was done by the Gomori method. The results of the reaction was read on the established area within the periarterial lymphatic tissue (PAL) using the Thomson point method. It was found that neonatal thymectomy leads to a decrease in the number of germinal centres and simultaneously to the reduction of the intensity of APh reaction within the spleen PAL. Following immunization of the thymectomized chickens, in comparison to the control (group) a change of kinetics of germinal centers formation was discovered, mainly of type I. It was ascertained that in the succeeding days after the antigen administration the intensity of APh reaction within PAL was directly proportional to the number of immature germinal centres of type II. The results demonstrated a distinct association between the bursodependent and thymodependent spleen structures reactivity and confirmed the importance of the functional state of the thymus.
The aim of study was to evaluate the participation of central κ-opioidergic receptors in the modulatory/ inhibitory effect of compound U 50,488H, a highly selective -opioid receptor agonist, on the spike burst activity of the rumen, reticulum and antrum prior to and 10 min after a one-minute i.c.v. infusion of norbinaltorphimine, a competitive κ-opioid receptor antagonist, in conscious sheep. U 50,488H was infused i.c.v. at doses of 0.1, 0.25 and 1.0 µg·kg⁻¹ b.w., norbinaltorphimine at doses 10 times higher. All the doses of U 50,488H infused i.c.v. nonsignificantly changed myoelectrical activity of the wall of the rumen, reticulum and antrum. The effects of U 50,488H were not changed by norbinaltorphimine previously infused at doses of 1.0, 2.5 and 10.0 µg·kg⁻¹ b.w. (i.e. at doses 10 times higher than U 50,488H). The results obtained indicate that central κ-opioid receptors did not participate in any action on myoelectrical activity of forestomachs and antrum in sheep.
The present study examined the participation of central µ-opioidergic receptors in the modulatory/inhibitory effect of D-Ala², N-Me-Phe⁴, Gly⁵-ol enkephalin (DAGO), a selective mu-opioid receptor agonist, on the spike burst activity of the rumen, reticulum and antrum prior to and 10 min after the intracerbroventriculary (i.c.v) - during 1 min - infusion of naloxonazine, a competitive mu-opioid receptor antagonist in sheep. DAGO was infused i.c.v. at a doses 0.02, 0.05, 0.1 and 1.0 µg × kg⁻¹, naloxonazine at doses 5 times higher. All the doses of DAGO administered i.c.v. significantly inhibited myoelectrical activity of the wall of the rumen, reticulum and abomasum. The effects of DAGO were prevented by naloxonazine previously infused at doses of 0.1, 0.5, 1.0 and 5.0 µg × kg⁻¹ (i.e. at a doses 5 times higher in comparison to doses of DAGO). The results of this present study indicate that central µ-opioid receptors participated in the inhibitory action of a specific opioid (DAGO) on myoelectrical activity of the forestomaches and antrum in sheep. Furthermore, this result suggests that it is a specific mu-receptor stimulation, because naloxonazine, a competitive µ-receptor antagonist, prevented the modulatory action of DAGO on the reticular, ruminal and antral motility in sheep.
The present study examined the participation of central δ-opioidergic receptors in the modulatory/ inhibitory effect of [D-Pen²-D-Pen⁵-enkephalin] (DPDPE), a highly selective delta-opioid receptor agonist, on the spike burst activity of the rumen, reticulum and antrum prior to and 10 min after the i.c.v. - during 1 min - infusion of naltrindole, a competitive ä-opioid receptor antagonist in conscious sheep. DPDPE was infused i.c.v. at the doses of 0.25, 0.5 and 1.0 mg × kg⁻¹ B.W., whereas naltrindole - at doses 10 times higher. All the doses of DPDPE infused i.c.v. significantly inhibited myoelectrical activity of the wall of the rumen and reticulum. The effects of DPDPE were prevented by naltrindole previously infused at the doses of 2.5, 5.0 and 10.0 mg × kg⁻¹ B.W. (i.e. at doses 10 times higher than those of DPDPE). The results obtained indicate that central δ-opioid receptors participated in the inhibitory action of specific opioid peptide (DPDPE) on myoelectrical activity of the forestomachs in sheep. Furthermore, these results suggest that it is a specific delta-receptor stimulation, because naltrindole, a compeptitive δ-receptor antagonist, prevented the modulatory/inhibitory action of DPDPE on the reticular and ruminal motility in sheep.
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