Participation of opiate pathways in the lateral hypothalamic area in the control of renal electrolyte and water excretion.
Injection of Met-enkephalin (0.05, 0.25 and 0.50 micrograms in 1 microliter) solutions into the lateral hypothalamic area (LHA) of unrestrained and unanesthetized rats caused a significant decrease of sodium (0.39 +/- 0.13 to 0.07 +/- 0.01, P less than 0.05) and potassium (0.61 +/- 0.17 to 0.21 +/- 0.04, P less than 0.05) excretion. When the blocking agent naloxone (0.20 micrograms in 1 microliter) was injected alone, a significant increase of sodium (0.34 +/- 0.04 to 0.96 +/- 0.28, P less than 0.05) and potassium (0.76 +/- 0.13 to 1.72 +/- 0.30, P less than 0.05) excretion was observed. However, a dose-response relationship was not observed. However, when in another experiment naloxone was injected before Met-enkephalin into the same area, reversal of the effect of naloxone occurred, with decreased sodium and potassium excretion. We conclude that the enkephalinergic pathway of the LHA when stimulated with Met-enkephalin plays an inhibitory role in the control of sodium and potassium excretion.
Perez
S E
SE
Departamento de Ciências da Saúde, Universidade Federal de São Carlos, SP, Brasil.
Silveira
J E
JE
Silva-Netto
C R
CR
D000818:Animals; D004334:Drug Administration Schedule; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000037:antagonists & inhibitors*; D007026:Hypothalamic Area, Lateral / Q000502:physiology*; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology*; D011188:Potassium / Q000652:urine*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000652:urine*
D009270:Naloxone; D004744:Enkephalin, Methionine; D012964:Sodium; D011188:Potassium