The actions of two monoamines on spinal motoneurons from stimulation of the locus coeruleus in the cat.
The present study investigates the role of the two putative amine transmitters (norepinephrine and serotonin) in mediating the facilitatory action following locus coeruleus (LC) stimulation on hindlimb flexor and extensor monosynaptic reflexes (MSRs) in unanesthetized, decerebrate cats. When administered sequentially, in either order, methysergide (a serotonergic blocker) and prazosin (an alpha 1-adrenergic blocker) were observed to cause subtotal, decremental changes in the potentiation of gastrocnemius-soleus and common peroneal MSRs by stimuli applied in the LC. These changes were determined to be independent of the blood pressure changes induced by the aminergic blockers. These results support the hypothesis that the facilitation of the group Ia reflex transmission in cat spinal cord by stimulation of LC is mediated in part by alpha 1-noradrenergic and serotonergic mechanisms.
Lai
Y Y
YY
Department of Physiology, Texas Tech University Health Sciences Center, Lubbock 79430.
Strahlendorf
H K
HK
Fung
S J
SJ
Barnes
C D
CD
D000320:Adrenergic Fibers / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D004558:Electric Stimulation; D006614:Hindlimb / Q000294:innervation; D008125:Locus Coeruleus / Q000187:drug effects / Q000502:physiology*; D008784:Methysergide / Q000494:pharmacology; D009046:Motor Neurons / Q000502:physiology*; D011224:Prazosin / Q000494:pharmacology; D012023:Reflex, Monosynaptic / Q000187:drug effects*; D012701:Serotonin / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D012701:Serotonin; D011224:Prazosin; D008784:Methysergide