Figure 1.
Chemical structures of A = NGD 98-2∶5-(2-Methoxy-4-trifluoromethoxyphenyl)-[N-(1-ethyl)propyl]-3-methoxy-6-methylpyrazine-2-amine tosylate.
B = NGD 9002∶5-(6-isopropyl-2-methylaminopyridin-3-yl)-[N-(1-ethyl)propyl]-3-methoxy-6-methylpyrazine-2-amine hydrochloride.
Figure 2.
Subcutaneous injection of CRF1 antagonists, NGD 9002 or NGD 98-2 prevents central (icv) or systemic (ip) CRF-induced stimulation of propulsive colonic motor function in conscious rats.
A: Rats with chronic icv cannula were pretreated sc with vehicle, NGD 98-2 or NGD 9002 and 60 min later were injected icv with saline or CRF and FPO monitored for 60 min. B: Rats were pretreated sc with either vehicle or NGD 98-2 (3, 10, 30 mg/kg) and 60 min later, they were injected ip with CRF or saline. As a positive control, a group of rats was injected sc with a known CRF1 antagonist, CP154,526, 60 min prior to ip CRF and FPO monitored for 60 min. Each bar represents the mean and SEM of 8 rats/group. *p<0.05 compared with sc vehicle+icv saline group (A) or vs sc vehicle+ip saline group (B); #p<0.05 compared with sc vehicle+icv CRF (A), or vs sc vehicle+ip CRF B), ANOVA, Student-Newman-Keuls.
Figure 3.
Oro-gastric (og) administration of CRF1 antagonist, NGD 98-2 or NGD 9002 blunts icv CRF-induced defecation and diarrhea in rats with chronic icv cannula.
NGD 98-2 (3, 10 and 30 mg/kg) or saline was given og 180 min before icv CRF or saline and fecal output (A) and diarrhea (B) were monitored for 1 h post icv injection. NGD 9002 (3, 10, 30 mg/kg) or saline was given 60 min before icv CRF and FPO (C) and diarrhea (D) monitored for 1 h post icv injection. Each bar in A and C represents the mean and SEM while each bar in B and D represents mean % of 8 rats/group. *p<0.05 compared with og vehicle+icv saline group (A-D); #p<0.05 compared with og vehicle+icv CRF (A-D), ANOVA, Student-Newman-Keuls; t-test; Fisher Exact test.
Figure 4.
Oro-gastric (og) administration of NGD 9002 exerted a non-significant trend towards reduction of ip CRF-induced FPO and diarrhea in rats.
Vehicle or NGD 9002 (3, 10 and 30 mg/kg) was given og 60 min before ip CRF-induced FPO (A) and diarrhea (B) which were monitored for the 60 min post ip injection. As a positive control, group of rats were pretreated with ip astressin (30 µg/kg), a non selective CRF1 and CRF2 receptor antagonist, just prior to ip CRF. Each bar in A represents the mean and SEM of FPO while in B they represent the mean % of 8 rats/group. *p<0.05 vs saline+vehicle or saline+NGD 9002 (30 mg/kg); #p<0.05 compared with the corresponding ip astressin+ip CRF. ANOVA, Student-Newman-Keuls; t-test; Fisher Exact test.
Figure 5.
Oro-gastric (og) administration of NGD CRF1 antagonist, NGD 98-2 or NGD 9002 reduces acute water avoidance stress (WAS)-induced stimulation of colonic propulsive motor function in rats.
Vehicle or NGD 98-2 (A) or NGD 9002 (B) at 3, 10 and 30 mg/kg was administered po and 180 min later (for NGD 98-2 group) or 60 min later (for NGD 9002 group), rats were exposed to WAS for 60 min. FPO was monitored during the 60 min stress session. Each bar represents the mean and SEM of 8 rats/group. *p<0.05 compared with vehicle og+no stress; #p<0.05 compared with vehicle og+WAS, ANOVA, Student-Newman-Keuls.
Figure 6.
Oro-gastric (og) pretreatment with NGD 98-2 blunts repeated tonic colorectal distention (CRD)-induced visceral sensitization response in conscious rats.
Representative trace of abdominal muscle electromyogram (EMG) of rats pretreated with vehicle (A) or NGD 9002 (B). Percent difference in the area under the curve of contraction (AUC) between the 1st and the 2nd dissentions is shown in C. Rats were chronically implanted with abdominal electrodes and ∼10 days later were pretreated og with vehicle or NGD 98-2 (30 mg/kg). After 30 min of habituation and 10 min basal recording, rats were submitted to the first CRD (10 minutes at 60 mm Hg) followed by a 30 min rest and a 2nd 10 min distention at 60 mmHg. Values are mean and SEM of percent differences between the first and second responses to CRDs of 9–10 rats/group. *p<0.05 versus vehicle, t-test or ANOVA, Student-Newman-Keuls.
Figure 7.
Oro-gastric (og) pretreatment with NGD 9002 blunts repeated tonic colorectal distention (CRD)-induced visceral sensitization response in conscious rats.
Rats were chronically implanted with abdominal electrodes and ∼10 days later were pretreated og with vehicle or NGD 9002 (0, 10 or 30 mg/kg). After 30 min of habituation and 10 min basal recording, rats were submitted to the 1st CRD (10 minutes at 60 mm Hg) followed by a 30 min rest and a 2nd 10 min distention at 60 mmHg. Representative trace of abdominal muscle electromyogram (EMG) of rats pretreated with vehicle (A) or NGD 9002 (B). Percent difference in the area under the curve of contraction (AUC) between the 1st and the 2nd dissentions in saline and NGD 9002 treated rats is shown in C. Values are mean and SEM of percent differences between the first and second responses to CRDs of 8–22 rats/group. *p<0.05 versus vehicle, t-test or ANOVA, Student-Newman-Keuls.