Browsing by Subject "Clonidine"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Publication
    Open Access
    Modifications in the distribution of met-enkephalin in the cat spinal cord after administration of clonidine. An immunocytochemical study
    (Murcia : F. Hernández, 1998) Vazquez, J.; Covenas, R.; Muñoz Madrid, Juan; Garcia, J.A.; Victoria, A.
    We have studied the modifications in the distribution of methionine-enkephalin in the cat spinal cord after intravenous or intrathecal administration of clonidine by using an immunocytochemical technique. In animals not treated with the substance, a very high density of immunoreactive fibers was found in layers I and 11; a high density in the dorso-lateral funiculus and in the reticular formation; a moderate density in layers 111, IV and V; and a low density in layer VI. However, after intravenous or intrathecal administration of clonidine a decrease in fibers containing met-enkephalin was observed in layers I and I1 (high or moderate density), the dorso-lateral funiculus, and the reticular formation (moderate or low density), and in layers IV and V (low or very low density). In all cases, the decrease in the immunoreactivity was more marked when clonidine was administered intrathecally. Our results suggest that clonidine induces the release of metenkephalin in the spinal cord. They further suggest that the opioid peptide released could be involved in the control of nociceptive transmission by inhibiting the release of neurotransmitters (e.g., substance P). In summary, our study shows that clonidine could be involved in antinociceptive mechanisms in the cat spinal cord.
  • Thumbnail Image
    Publication
    Open Access
    Modifications in the distribution of met-enkephalin in the pons of the cat, following the intravenous administration of clonidine: An immunocytochemical experimental study
    (Murcia : F. Hernández, 1998) Vazquez, J.; Muñoz Madrid, Juan; García, J.C.
    The distribution of rnet-enkephalin in the cat and its rnodifications following the stirnulation by intravenous clonidine, was studied with indirect irnrnunocytochernical techniques. We observed a decrease in the irnrnunoreactivity of rnet-enkephalin following the adrninistration of clonidine, relative to the controls, in the following structures: locus coeruleus, nucleus cuneforrnis, forrnatio reticularis, nucleus gigantocellularis, nucleus reticularis lateralis, nucleus reticularis, nucleus reticularis parvocellularis, nucleus sensorius superior n. trigernini, nucleus raphes, substantia grisea periventricularis, nucleus erninentiae teretis, colliculus inferior, nucleus rnotorius n. trigemini, nucleus tracto spinalis n. trigernini, tractus spinalis n. trigernini and nucleus tracto rnesencephalici n. trigernini. These experimental observations link the irnrnunoreactivity changes to the structures that are associated with the direct action of clonidine and conclude that the pars rnetencephalinergicus of the efferent pontine pathway of pain is in rnorpho-functional relationship with the analgesia produced by clonidine; an analgesic of an endogenous opiate character.