Effect of opioid peptides on the paraventricular nucleus of the guinea pig hypothalamus is mediated by mu-type receptors.
The effects of opioid peptides on paraventricular neurones were investigated by using intracellular recordings from hypothalamic slices of the guinea pig. Forty-eight out of 128 neurones were hyperpolarized by DAGO, a synthetic structural analogue of enkephalin selective for mu-receptors. This effect was concentration-dependent and reversibly suppressed by naloxone. DPLPE, a selective delta-agonist, and U-50,488, a selective kappa-agonist, had no effect. The localization and the size of the recorded perikarya were assessed following injection of the fluorescent dye Lucifer yellow. Most of the DAGO-responsive neurones were located within the paraventricular nucleus, some of them in the region of the nucleus which is rich in vasopressin-containing cells, as shown by immunocytochemistry. DAGO-sensitive cells were found among magnocellular as well as parvocellular neurones.
Wuarin
J P
JP
Department of Physiology, University Medical Center, Geneva, Switzerland.
Dubois-Dauphin
M
M
Raggenbass
M
M
Dreifuss
J J
JJ
D000818:Animals; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D017450:Receptors, Opioid, mu
D004745:Enkephalins; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009270:Naloxone