Serotonin receptor 2B induces visceral hyperalgesia in rat model and patients with diarrhea-predominant irritable bowel syndrome

Table 1 Gene primer sequences (5’-3’)

Gene	Primer sequences (5’-3’)
ACTB	Forward	GGCTGTATTCCCCTCCATCG
	Reverse	CCAGTTGGTAACAATGCCATGT
5-HT2B receptor	Forward	AGAACCAGGGGAATACAG
	Reverse	GGGAAATGGCACAGAGA
TRPV1	Forward	TGAAGCCGTTGCTCAGAATAACTG
	Reverse	CTCAGGGTCTTTGAACTCGTT

5-HT_2B receptor: Serotonin receptor 2B; TRPV1: Transient receptor potential vanilloid type 1.

Table 2 Characteristics of the study subjects, n (%)

Clinical characteristics	Subjects (n = 43)			IBS subtype (n = 28)
	IBS (n = 28)	Control (n = 15)	P value	IBS-D (n = 18)	IBS-C (n = 18)	P value
Age	51.2 (10.2)	51.1 (10.3)	0.96	51.4 (9.8)	51.0 (11.5)	0.93
Sex			0.86
Male	12 (42.9)	6 (40.0)		8 (44.4)	4 (40.0)	1.00
Female	16 (51.7)	9 (60.0)		10 (55.6)	6 (60.0)
Severity of abdominal pain			< 0.001			0.49
Absent (0)	0 (0.0)	8 (53.4)		/	/
Mild (1)	10 (35.7)	7 (46.7)		7 (38.9)	3 (30.0)
Relevant (2)	12 (42.9)	0 (0.0%)		8 (44.4)	4 (40.0)
Severe (3)	6 (21.4)	0 (0.0)		3 (16.7)	3 (30.0)
Frequency of abdominal pain			< 0.001			0.88
Absent (0)	0 (0.0)	9 (60.0)		/	/
Up to 1 day/week (1)	9 (32.1)	6 (40.0)		6 (33.3)	3 (30.0)
2 or 3 days/week (2)	14 (50.0)	0 (0.0)		9 (50.0)	5 (50.0)
4-6 days/week (3)	4 (14.3)	0 (0.0)		2 (11.1)	2 (20.0)
Daily (4)	1 (3.57)	0 (0.0)		1 (5.6)	0 (0.0)

Depending on the distribution of the variables, Student's t-test, Chi-square test, or Wilcoxon rank sum was used to test for differences in parameters between groups. Continuous variables are presented as arithmetic mean ± SD. Categorical variables are presented as numbers (percentages). IBS: Irritable bowel syndrome; IBS-D: IBS with diarrhea; IBS-C: IBS with constipation.