[The neurochemical mechanisms of the inhibitory influences of stimulation of the central gray substance on the high-threshold reflex activity of the reticular formation].
Influences of bulbar microinjections of some neuromodulator antagonists (methysergide, haloperidol, naloxone) on depression dynamics of spino-bulbo-spinal (SBS) reflex from the periaqueductal grey (PAG) stimulation were studied in chloralose anesthetized rats. Microinjections were made into the reticular gigantocellular nucleus which is a main supraspinal centre of SBS reflexes. It is found that methysergide administration (10(-5) mol/l) causes a considerable (two to four times as less) decrease of SBS-reflex depression evoked by PAG stimulation by a short high-frequency series of stimuli. Long-lasting depression evoked usually by a long train of PAG stimuli is less reduced: from 6-10 to 2.5-4 min. A considerable (2 to 5 times) shortening of this depression is revealed after naloxone injections (10(-5)-10(-4) mol/l). The most expressed diminution of all types of inhibitions is shown to occur after haloperidol administration. Data obtained evidence that all the studied neuromodulatory systems (5-HT, catecholamine and opioidergic ones) are involved to inhibitory action of PAG on high-threshold reflex activity of the reticular formation. Some properties of neurochemical mechanisms of the studied PAG-evoked depression are discussed.
M V
MV
Karpukhina
A P
AP
Gokin
N E
NE
Tikhomirov
D000818:Animals; D004298:Dopamine / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D008636:Mesencephalon / Q000187:drug effects / Q000502:physiology*; D008784:Methysergide / Q000494:pharmacology; D008845:Microinjections; D009270:Naloxone / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology*; D051381:Rats; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D012154:Reticular Formation / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology
D018377:Neurotransmitter Agents; D012701:Serotonin; D009270:Naloxone; D006220:Haloperidol; D004298:Dopamine; D008784:Methysergide
Neĭrokhimicheskie mekhanizmy ugnetaiushchikh vliianiĭ stimuliatsii tsentral'nogo serogo veshchestva na vysokoporogovuiu reflektornuiu aktivnost' retikuliarnoĭ formatsii.