Opioid binding sites in jerboa (Jaculus orientalis) brain: a biochemical comparative study in the awake-active and induced hibernating states.
1. Using tritiated ligands [3H]DADLE, [3H]DAGO, [3H]EKC and [3H]Bremazocine, we have demonstrated the presence of delta, mu and kappa sites in brain membranes from jerboa (Jaculus orientalis), a desert rodent and a true hibernator. 2. A comparative study was realized in the case of the induced hibernating state, indicating a reduction of binding capacities during the hibernation state. 3. Using radioimmunoassay, the endogenous pentapeptide methionine-enkephalin (Met-enk) was evaluated in different areas of jerboa brain in comparison with the effect of induced hibernation on the level of Met-enk. 4. A thermodynamic analysis of the effect of temperature on the binding of opioids, indicates that the hibernating and the active state are energetically different. delta G degrees, delta H degrees and delta S degrees were calculated. A break of the Van't Hoff plot was observed in the active state at 15 degrees C, indicating a possible transition state of membranous phospholipids and/or proteins. 5. The role of phospholipids was studied, using the effect of phospholipase A2 and membrane reconstitution. Phospholipids play a key role in the opioid binding.
Bourhim
N
N
Laboratoire de Biochimie, Biologie Cellulaire et Moléculaire, Faculté des Sciences Ain chock, Casablanca, Morocco.
Elkebbaj
M S
MS
Ouafik
L
L
Chautard
T H
TH
Giraud
P
P
Oliver
C
C
D000818:Animals; D001923:Brain Chemistry / Q000502:physiology*; D004744:Enkephalin, Methionine / Q000032:analysis; D005260:Female; D006605:Hibernation / Q000502:physiology*; D008297:Male; D008563:Membrane Lipids / Q000737:chemistry; D008566:Membranes / Q000737:chemistry; D009474:Neurons / Q000737:chemistry; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010743:Phospholipids / Q000737:chemistry; D011863:Radioimmunoassay; D011869:Radioligand Assay; D011957:Receptors, Opioid / Q000032:analysis*; D012377:Rodentia / Q000378:metabolism*; D013696:Temperature; D014851:Wakefulness / Q000502:physiology*
D008563:Membrane Lipids; D010743:Phospholipids; D011957:Receptors, Opioid; D004744:Enkephalin, Methionine; D010741:Phospholipases A; D054467:Phospholipases A2