Cholinergic giant migrating contractions in conscious mouse colon assessed by using a novel noninvasive solid-state manometry method: modulation by stressors - PubMed (original) (raw)

Cholinergic giant migrating contractions in conscious mouse colon assessed by using a novel noninvasive solid-state manometry method: modulation by stressors

G Gourcerol et al. Am J Physiol Gastrointest Liver Physiol. 2009 May.

Abstract

There is a glaring lack of knowledge on mouse colonic motility in vivo, primarily due to unavailability of adequate recording methods. Using a noninvasive miniature catheter pressure transducer inserted into the distal colon, we assessed changes in colonic motility in conscious mice induced by various acute or chronic stressors and determined the neurotransmitters mediating these changes. Mice exposed to restraint stress (RS) for 60 min displayed distal colonic phasic contractions including high-amplitude giant migrating contractions (GMCs), which had peak amplitudes >25 mmHg and occurred at a rate of 15-25 h(-1) of which over 50% were aborally propagative. Responses during the first 20-min of RS were characterized by high-frequency and high-amplitude contractions that were correlated with defecation. RS-induced GMCs and fecal pellet output were blocked by atropine (0.5 mg/kg ip) or the corticotrophin releasing factor (CRF) receptor antagonist astressin-B (100 microg/kg ip). RS activated colonic myenteric neurons as shown by Fos immunoreactivity. In mice previously exposed to repeated RS (60 min/day, 14 days), or in transgenic mice that overexpress CRF, the duration of stimulation of phasic colonic contractions was significantly shorter (10 vs. 20 min). In contrast to RS, abdominal surgery abolished colonic contractions including GMCs. These findings provide the first evidence for the presence of frequent cholinergic-dependent GMCs in the distal colon of conscious mice and their modulation by acute and chronic stressors. Noninvasive colonic manometry opens new venues to investigate colonic motor function in genetically modified mice relevant to diseases that involve colonic motility alterations.

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Figures

Fig. 1.

Conscious mouse colon contractile pressure changes and signal analysis. Miniature pressure transducer catheters were placed in the colon of mice (2 and 4 cm proximal to the anus) under brief isoflurane anesthesia. Upon recovery from anesthesia, mice were placed in a partial restraint tube and colonic pressures were simultaneously recorded. A: representative colon pressure raw traces at 4 and 2 cm. Note the distinctive signature of the sharp rising and short-duration pressure excursions that simultaneously occur at the 2- and 4-cm sites (*) owing to abdominal muscle contractions and the slow and long-duration pressure excursions that occur owing to colonic contractions. B: colon traces smoothed with 2-s time constant. Pressure changes due to abdominal contractions and breathing are removed by the 2-s smoothing whereas the colonic pressure changes are not (arrows show aboral propagation). C: real-time area under the curve (AUC) of contraction of the colon. Numbers are distance (cm) of the pressure sensor from the anal verge. D_–_F: arrows show propagative (aboral or oral) contractions, and solid lines show simultaneously occurring contractions or those that were seen only at 1 site.

Fig. 2.

Distal colon contractions pattern in conscious mouse placed in partial restraint tube. A miniature pressure transducer catheter was placed in the distal colon of mice (2 cm proximal to the anus) under brief isoflurane anesthesia. A: representative raw distal colon pressure trace. Note the enhanced contractile response during the first 20 min of placement of mice in the tube that becomes stable and low after 20 min. B: time course of AUC (mmHg × min) over a 60-min period. C: mean AUC of the phasic component of the intraluminal pressure trace (pAUC; mmHg × min) of the first 20 min (0–20) vs. the mean pAUC (mmHg*min) of the subsequent 40 min (20–60); n = 12/group. *P < 0.05 vs. 0–20 min; ANOVA.

Fig. 3.

Distal colonic contraction profile (amplitude, duration, and frequency of contractions) in acutely stressed conscious mice. A miniature pressure transducer catheter was placed in the distal colon of mice (2 cm proximal to the anus) under brief isoflurane anesthesia. A: plots showing distal colonic contractions profile [number (Nb), duration, and amplitude] during the first 20 min and during the 20- to 60-min stress period. B: frequency of contractions as a function of amplitude or duration of contractions; 732 contractions from n = 12 mice were analyzed. *P < 0.05 vs. the corresponding 0–20 min time period; ANOVA.

Fig. 4.

Propagative characteristics of conscious mouse distal colonic contractions. A miniature pressure transducer catheters were placed in the distal colon of mice (2 and 4 cm proximal to the anus) under brief isoflurane anesthesia. A: number of propagated and nonpropagated contractions. B: correlation between the amplitude of contractions and their chance to be propagated. C: mean amplitude of propagated vs. nonpropagated contractions; n = 8 mice. *P < 0.05 vs. nonpropagated contractions.

Fig. 5.

Corticotropin releasing factor (CRF) receptor antagonist astressin-B blocked acute restraint stress-induced distal colonic contraction in conscious mice. A miniature pressure transducer catheter was placed in the distal colon of mice (2 cm proximal to the anus) under brief isoflurane anesthesia. Mice were pretreated (−3–5 min) with either saline (0.1 ml ip) or astressin-B (100 μg/kg ip) and placed for 60 min in a partial restraint tube for distal colonic pressure recording. A: representative raw trace of distal colon pressure changes of saline- (top) or astressin-B- (bottom) pretreated mice. B: time course (during 60 min) AUC of the distal colon. C: AUC of distal colon pressure changes at different time intervals during the 60-min recording period. D: frequency of contractions as a function of amplitude or duration of contractions. *P < 0.05 vs. the corresponding saline; saline n = 12, astressin-B n = 8; ANOVA.

Fig. 6.

Differential effects of cholinergic or nitrergic blockade on conscious mouse distal colon contractions pattern. A miniature pressure transducer catheter was placed in the distal colon of mice (2 cm proximal to the anus) under brief isoflurane anesthesia. Mice were pretreated (3–5 min) with either saline (0.1 ml ip), atropine (0.5 mg/kg ip) or

-NAME (10 mg/kg ip) and placed in a partial restraint tube for distal colonic pressure recording for 60 min. A: representative raw traces of distal colonic contractions. B: time course of colonic pAUC (mmHg × min) during the 60-min period. C: mean colonic pAUC (mmHg × min) of the 0- to 10-, 10- to 20-, and 20- to 60-min periods. *P < 0.05 vs. the respective saline group; n = 6/group; ANOVA.

Fig. 7.

Acute partial restraint stress activates distal colonic myenteric neurons. Distal colon longitudinal muscle myenteric plexus (LMMP) whole mount tissue from control and mice submitted to 60 min of acute partial restraint stress were processed for Fos immunohistochemistry. A: photomicrographs of distal colon LMMP from control (no stress) and acute stress mice. B: number of Fos immunoreactive LMMP neurons (nb/ganglia) in control and stressed mice (n = 6/group). *P < 0.05 vs. no-stress (control). Scale bar = 100 μm.

Fig. 8.

Effect of chronic stress on distal colonic contractions in conscious mice. A miniature pressure transducer catheter was placed in the distal colon of mice (2 cm proximal to the anus) under brief isoflurane anesthesia. CRF-overexpressing (OE) mice (n = 10), a genetic model of chronic stress or control (wild-type littermates and C57Bl/6) mice submitted to 15 consecutive sessions of partial restraint stress (60 min/day, for 15 days, colon contractions monitored on the 15th day, n = 6) or control mice (no prior stress, n = 12) were placed in the partial restraint stress tube and distal colonic contractions recorded. A: representative raw trace of distal colon in mice submitted to a single acute stress (top), mice submitted to chronic stress [15 consecutive sessions of acute partial restraint stress (60 min·h−1·day−1) (middle), and CRF-OE mice (bottom)]. B: time course (during 60 min) AUC of the distal colon in the acute vs. the chronic stress groups. C: AUC of distal colonic at different time intervals during the 60-min recording period. D: frequency of contractions as a function of amplitude or duration of contractions. *P < 0.05 vs. the corresponding 0- to 10-min time period, #P < 0.05 vs. the corresponding acute stress; ANOVA.

Fig. 9.

Correlation of distal colonic contractions and fecal pellet output. A miniature pressure transducer catheter was placed in the distal colon of mice (2 cm proximal to the anus) under brief isoflurane anesthesia and mice were placed for 60 min in a partial restraint tube. Distal colonic pressure changes as well as the 60-min fecal pellet output were monitored. Distal colon contractility during the first 20 min is positively correlated with the 60-min fecal pellet expulsion in conscious mice (n = 60, r = 0.43, P < 0.05).

Fig. 10.

Effect of interoceptive stress, abdominal surgery, on distal colonic contractions in conscious mice. Under brief isoflurane anesthesia mice underwent either sham treatment (only anesthesia) or abdominal surgery (abdominal incision, opening of the peritoneum, and palpation of the cecum for 1 min) and suturing of the incision. Colonic contractions before the surgery (30 min) and after surgery (60 min) were recorded and compared. A: representative raw trace of distal colonic contractions in sham (top) and surgery mice (bottom). B: time course of the baseline and postsurgery period AUC in sham and surgery groups. C: total baseline and postsurgery AUC in sham and surgery groups. *P < 0.05 vs. baseline and sham; n = 6/group; ANOVA.

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Cholinergic giant migrating contractions in conscious mouse colon assessed by using a novel noninvasive solid-state manometry method: modulation by stressors - PubMed (original) (raw)