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Regional haemodynamic effects of μ‐, δ‐, and κ‐opioid agonists microinjected into the hypothalamic paraventricular nuclei of conscious, unrestrained rats
Author(s) -
Bachelard Hélène,
Pître Maryse
Publication year - 1995
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1995.tb14976.x
Subject(s) - endocrinology , medicine , agonist , vasodilation , hemodynamics , damgo , enkephalin , opioid , vasoconstriction , opioid peptide , blood pressure , chemistry , opioid receptor , receptor
1 The cardiovascular effects of bilateral injection into the hypothalamic paraventricular nuclei of selective μ‐, δ‐, and κ‐opioid receptor agonists were investigated in conscious, unrestrained Wistar Kyoto rats, chronically instrumented with pulsed Doppler flow probes for measurement of regional haemodynamics. 2 The selective μ‐agonist [D‐Ala 2 , MePhe 4 , Gly 5 ol]enkephalin (DAMGO), injected bilaterally into the hypothalamic paraventricular nuclei (0.01‐1.0 nmol), caused increases in blood pressure, tachycardias, vasoconstriction in renal and superior mesenteric vascular beds and substantial vasodilatation in the hindquarter vascular bed. 3 The administration of increasing doses (0.01–5.0 nmol) of the selective δ‐agonist [D‐Phe 2,5 ]enkephalin (DPDPE) or the selective κ‐agonist, U50488H into the paraventricular nuclei (PVN) had no significant effect on blood pressure, heart rate, or regional haemodynamics. 4 Together, the present results are further evidence of a role for opioid peptides, especially acting at μ‐receptors in the PVN, in the central regulation of the cardiovascular system, whereas a role for opioid peptides, acting at δ‐ and κ‐receptors in the PVN, seems less obvious from the present results.