Pineal response to isoproterenol in rats chronically treated with electroconvulsive shock.
Chronic electroconvulsive shock (ECS) has been shown to induce a downregulation of beta 1-adrenergic receptors in the rat cerebral cortex. Because the secretion of melatonin in the pineal gland is regulated primarily by beta 1-adrenoceptors, in the present study we investigated the effect of chronic administration of ECS on pineal beta-adrenergic responsiveness to isoproterenol. To this purpose, young adult male rats received once daily for 8 days ECS (80 mA, 0.5 s) or sham ECS. On the day after the last ECS or sham treatment, they were injected with isoproterenol hydrochloride (1 mg/kg SC) or volume-matched saline at 1600 h. Two hours later they were killed by decapitation. Results showed that the isoproterenol-induced increase in the pineal melatonin content was blunted in rats treated with ECS as compared to sham-treated animals (shock x drug interaction = p < 0.01). These data indicate that chronic ECS treatment affects beta 1 receptor-mediated melatonin production in the pineal gland. Further studies need to elucidate whether the blunted melatonin response to isoproterenol in ECS-treated rats is due to a downregulation of pinealocyte beta-adrenergic receptors.
Institute of Psychiatry, First Medical School, University of Naples, Italy.
P
P
Monteleone
M
M
D'Istria
B
B
De Luca
I
I
Serino
M
M
Maj
D
D
Kemali
D000704:Analysis of Variance; D000818:Animals; D004597:Electroshock; D004830:Epilepsy, Tonic-Clonic / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D008550:Melatonin / Q000097:blood / Q000378:metabolism*; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism
D011943:Receptors, Adrenergic, beta; D008550:Melatonin; D007545:Isoproterenol