Effects of naloxone on c-jun/AP-1 in met-enkephalin-and FMRFamide-immunreactive neurons of a gastropod snail.
1. Opioid- and FMRFamide (FMRFa)-ergic systems are believed to play antagonistic behavioral roles in both higher and lower animals. In our previous experiments on a snail, behavioral choice has been demonstrated to be dependent on a balance between FMRFa and enkephalins [7]. Here, we examined if the disturbance of the balance causes changes in the activity of both systems. Opiate receptor blocker naloxone was applied and its effect on c-jun expression of met-enkephalin (MEnk)- and FMRFa-ergic neurons was examined immunocytochemically in terrestrial gastropod snail Cepaea nemoralis. 2. In control, untreated snails, central neurons with c-jun/AP-1-like-immunoreactivity were found to occur. These included MEnk-, FMRFa- and 5HT-immunoreactive (-ir) neurons, as was revealed by double-labelling. 3. After treatment with naloxone for 4 h, the following changes were observed: (i) increase in the number of MEnk-ir neurons; increase in the number of neurons showing c-jun/AP-1 and MEnk double-labeling; (ii) disappearance of c-jun/AP-1-immunoreactivity from some FMRFa-ir neurons. 4. It is suggested that immediate early genes are involved in the mechanisms responsible for the reciprocal regulation of the opioid and antiopioid neuropeptide systems.
Dyakonova
V
V
Institute of Developmental Biology, Russian Academy of Sciences, Moscow.
Elofsson
R
R
Carlberg
M
M
Sakharov
D A
DA
D000818:Animals; D004744:Enkephalin, Methionine / Q000378:metabolism*; D019835:FMRFamide / Q000494:pharmacology*; D007150:Immunohistochemistry; D009270:Naloxone / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D012908:Snails
D009270:Naloxone; D004744:Enkephalin, Methionine; D019835:FMRFamide