Involvement of melatonin metabolites in the long-term inhibitory effect of the hormone on rat spinal nociceptive transmission.
There is evidence that melatonin and its metabolites could bind to nuclear sites in neurones, suggesting that this hormone is able to exert long-term functional effects in the central nervous system via genomic mechanisms. This study was designed to investigate (i) whether systemically administered melatonin can exert long-term effects on spinal cord windup activity, and (ii) whether blockade of melatonin degradation with eserine could prevent this effect. Rats receiving melatonin (10 mg/kg ip), the same dose of melatonin plus eserine (0.5 mg/kg ip), or saline were studied. Seven days after administration of the drugs or saline, spinal windup of rats was assessed in a C-fiber reflex response paradigm. Results show that rats receiving melatonin exhibited a reduction in spinal windup activity. This was not observed in the animals receiving melatonin plus eserine or saline, suggesting a role for melatonin metabolites in long-term changes of nociceptive transmission in the rat spinal cord.
Mondaca
Mauricio
M
Institute of Nutrition and Food Technology (INTA), University of Chile, P.O. Box 138-11, Santiago, Chile.
Hernández
Alejandro
A
Valladares
Luis
L
Sierralta
Walter
W
Noseda
Rodrigo
R
Soto-Moyano
Rubén
R
D008735:5-Methoxytryptamine / Q000378:metabolism; D000581:Amidohydrolases / Q000037:antagonists & inhibitors; D000818:Animals; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D004558:Electric Stimulation; D008297:Male; D008550:Melatonin / Q000378:metabolism* / Q000494:pharmacology*; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects*; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects*
D002800:Cholinesterase Inhibitors; D008735:5-Methoxytryptamine; D010830:Physostigmine; D000581:Amidohydrolases; C072890:melatonin deacetylase; C019665:amidase; D008550:Melatonin