Changes in the activity of rat cortical and hippocampal neurones after the iontophoretic administration of beta-endorphin, glutamate and GABA.
The effect of microiontophoretically administered beta-endorphin on the activity of 62 cortical and hippocampal neurones was studied in acute experiments on 14 rats. The effectiveness of beta-endorphin was first of all verified in the isolated guinea pig ileum, the mouse was deferens and in a study if its analgetic and catatonic effect in rats. Beta-endorphin only mildly depressed the spontaneous activity of cortical neurones, but markedly inhibited the activity stimulated by the microiontophoretic administration of glutamate. In the hippocampus, beta-endorphin stimulated the activity of all the studied neurones when only low ejection currents were used and activation persisted for 1-4 min after terminating administration. With higher ejection currents, the discharge frequency rose enormously and not even GABA blocked this effect. The excitatory effect of beta-endorphin on the hippocampal neurones may possibly be the basis of the epileptogenic action of this substance.
Strejcková
A
A
Jakoubek
B
B
Kraus
M
M
Mares
P
P
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004594:Electrophysiology; D004723:Endorphins / Q000008:administration & dosage* / Q000494:pharmacology; D005971:Glutamates / Q000008:administration & dosage* / Q000494:pharmacology; D018698:Glutamic Acid; D006168:Guinea Pigs; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007478:Iontophoresis; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage* / Q000494:pharmacology
D004723:Endorphins; D005971:Glutamates; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D001615:beta-Endorphin