Periaqueductal grey matter stimulation produces naloxone sensitive inhibition of reticular neurones in rat caudal medulla.
Neurones in the caudal medulla reticular formation (CRF) are excited by peripheral noxious stimuli and thus may have a role in nociceptive information processing. Stimulation of sites within the dorsal periaqueductal grey matter (PAG) produced a prolonged inhibition of CRF neurones. On 11 of 16 neurones tested microiontophoretic application of naloxone was found to attenuate these inhibitions suggesting that the neurotransmitter involved may have been an endogenous opioid. Histochemical localization of beta endorphin-like immunoreactivity (beta ELI) showed fibres containing beta ELI in the vicinity of PAG stimulation sites and scattered individual fibres with short collateral branches in the vicinity of recording sites in CRF.
D000698:Analgesia; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D009270:Naloxone / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats
D009270:Naloxone