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Involvement of periaqueductal gray matter in intestinal effect of centrally administered morphine
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Involvement of periaqueductal gray matter in intestinal effect of centrally administered morphine. - M. Sala, D. Parolaro, G. Crema, L. Spa& G. Giagnoni, R. Cesana and E. Gori, Europ. J. Pharmacol., 91 (1983) 251-254. Recent evidence indicates that the inhibition of intestinal motility by opioids is centrally and peripherally mediated. In this paper it is shown that microinjections of morphine in the rat periaqueductal gray matter (PAG) inhibited intestinal transit in linear relation to the log of the dose administered (in the range from 5 to 20 pg/rat). This linear regression was parallel with that obtained on intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) administration of morphine and the intracerebral (i.c.) route was calculated to be 4 times more potent than the i.c.v. route and 189 times more potent than the i.p. route. Monolateral electrolytic lesions into the PAG abolished the intestinal effect of i.c.v. morphine to a large extent. PAG, containing a high density of p-type opiate receptors subserves not only the analgesic effect of morphine but appears to be an important site for the central component of morphine’s intestinal effect.
PEPTIDES Preferential immunohistochemical localization of vasoactive intestinal polypeptide (VIP) in the sacral spinal cord of the cat: light and electron microscopic observations. - C.N. Honda, M. Rethelyi and P. Petrusz, J. Neurosci., 3 (1983) 2183-2196. This paper compares the distribution of dynorphin with that of other endogenous opioid peptides and concludes that although there is some gross overlap, the distribution of dynorphin is distinct from that of the other opioid peptides. For example, in the dorsal horn, both enkephalin and dynorphin fibers are found in laminae I and IIa, while a dense enkephalin network also occupies lamina IIb. Differences were also observed in the distribution of dynorphin and enkephalin in the medulla, mesencephalon, hypothalmus and forebrain. Dynorphin-immunoreactive neurons in the central nervous system of the rat. - S.R. Vincent, T. Hiikfelt, I. Christensson and L. Terenius, Neurosci. Lett., 33 (1982) 185-190. In this study, the distribution in the spinal cord of vasoactive intestinal polypeptide-like immunoreactivity (VIP) was compared to that of substance P, somatostatin and cholecystokinin-8 (CCK). The major finding is that, whereas substance P, somatostatin and CCK are present in the superficial dorsal horn throughout the length of the spinal cord, VIP is concentrated at sacral levels. Similar results have been reported by Basbaum and Glazer in Somatosensory Research, Vol. 1, pages 69-82,1983 and by DeGroot et al., Journal of the Autonomic Nervous System, Vol. 7, pages 339-350, 1983.
Involvement of periaqueductal gray matter in intestinal effect of centrally administered morphine. - M. Sala, D. Parolaro, G. Crema, L. Spa& G. Giagnoni, R. Cesana and E. Gori, Europ. J. Pharmacol., 91 (1983) 251-254. Recent evidence indicates that the inhibition of intestinal motility by opioids is centrally and peripherally mediated. In this paper it is shown that microinjections of morphine in the rat periaqueductal gray matter (PAG) inhibited intestinal transit in linear relation to the log of the dose administered (in the range from 5 to 20 pg/rat). This linear regression was parallel with that obtained on intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) administration of morphine and the intracerebral (i.c.) route was calculated to be 4 times more potent than the i.c.v. route and 189 times more potent than the i.p. route. Monolateral electrolytic lesions into the PAG abolished the intestinal effect of i.c.v. morphine to a large extent. PAG, containing a high density of p-type opiate receptors subserves not only the analgesic effect of morphine but appears to be an important site for the central component of morphine’s intestinal effect.
PEPTIDES Preferential immunohistochemical localization of vasoactive intestinal polypeptide (VIP) in the sacral spinal cord of the cat: light and electron microscopic observations. - C.N. Honda, M. Rethelyi and P. Petrusz, J. Neurosci., 3 (1983) 2183-2196. This paper compares the distribution of dynorphin with that of other endogenous opioid peptides and concludes that although there is some gross overlap, the distribution of dynorphin is distinct from that of the other opioid peptides. For example, in the dorsal horn, both enkephalin and dynorphin fibers are found in laminae I and IIa, while a dense enkephalin network also occupies lamina IIb. Differences were also observed in the distribution of dynorphin and enkephalin in the medulla, mesencephalon, hypothalmus and forebrain. Dynorphin-immunoreactive neurons in the central nervous system of the rat. - S.R. Vincent, T. Hiikfelt, I. Christensson and L. Terenius, Neurosci. Lett., 33 (1982) 185-190. In this study, the distribution in the spinal cord of vasoactive intestinal polypeptide-like immunoreactivity (VIP) was compared to that of substance P, somatostatin and cholecystokinin-8 (CCK). The major finding is that, whereas substance P, somatostatin and CCK are present in the superficial dorsal horn throughout the length of the spinal cord, VIP is concentrated at sacral levels. Similar results have been reported by Basbaum and Glazer in Somatosensory Research, Vol. 1, pages 69-82,1983 and by DeGroot et al., Journal of the Autonomic Nervous System, Vol. 7, pages 339-350, 1983.