Manometric patterns of rat colonic motor activity and defecation. Effect of selective 5HT1A agonist 8-OH-DPAT.
We investigated in conscious and unrestrained rats, the major patterns of colonic pressure waves, as related to defecation. A manometric low compliance perfusion system, which was set at a very low flow rate (0.03 ml/min), permitted simultaneous recordings of intraluminal pressure in the proximal, transverse, and distal colon. Pressure waves in control rats reflected two types of motor activity: short-duration waves (< 15 sec), that were frequent throughout the colon (about 40-90/hr with aborally decreasing frequency), and propulsive, long-duration, high-amplitude waves (> 15 sec, > 15 mm Hg) that occurred only occasionally (1/hr or less) in the transverse and distal, but not in the proximal colon; these waves appeared to migrate aborally and were associated with defecation. The serotonin 5HT1A agonist 8-OH-DPAT dramatically and dose-dependently increased the frequency of long-duration, high-amplitude waves in the transverse and distal colon, and concurrently promoted defecation; these effects were prevented by the putative 5HT1A antagonist pindolol. We conclude that 5HT1A agonists such as 8-OH-DPAT may promote defecation and occurrence of propulsive waves through the same serotoninergic mechanism.
Croci
T
T
Research Center Sanofi-Midy S.p.A., Milano, Italy.
Basilisco
G
G
Bassani
A
A
Manara
L
L
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D003106:Colon / Q000187:drug effects*; D003672:Defecation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005769:Gastrointestinal Motility / Q000187:drug effects*; D008297:Male; D008365:Manometry; D008991:Monitoring, Physiologic; D051381:Rats; D015203:Reproducibility of Results
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin