Effects of nitric oxide on gastric ulceration induced by nicotine and cold-restraint stress

Table 1 Effects of nicotine and acute nitric oxide treatment on gastric ulceration and adhesion mucus content in rats

Experimentalgroup	No. of rats with lesions	Ulcer index (mm)	Adhesion mucus content (μg/g wet glandular tissue)
A. No stress (unrestrained at 22 °C for 2 hours)
Tap water	2 (7)	0.04 ± 0.03	382 ± 38
Nicotine alone	3 (8)	0.05 ± 0.03	283 ± 27a
Nicotine + NO (acute)	2 (8)	0.06 ± 0.04	276 ± 28a
B. Stress (restrained at 4 °C for 2 hours)
Tap water	8 (8)c	6.0 ± 0.7	200 ± 17b
Nicotine alone	8 (8)c	19.0 ± 1.7ad	152 ± 14ab
Nicotine + NO (acute)	7 (7)c	17.8 ± 1.7ad	143 ± 15ab

Values are mean ± SD. Number of rats in each group is shown in parentheses. Lesions: Only petechiae in stomach were seen in non-stressed condition. Both petechiae and haemorrhagic ulcer in stomach were observed in stressed condition. Tap water: Rats drank water as control. Nicotine alone: Rats drank nicotine water (50 µg/ml) for 20 days. Nicotine + NO (acute): Rats drank nicotine water (50 µg/ml) for 20 days. Rats were given NO donor 60 min and 10 min twice by oral gavages before stress.

^aP < 0.05 when compared to its own tap water control in A or B.

^bP < 0.05,

^cP < 0.01,

^dP < 0.001 when compared to the corresponding control in A.

Table 2 Changes of ulcer index and adhesion mucus content after quit nicotine intake alone or with chronic nitric oxide donor (NO) treatment

Experimental group	No. of rats with lesions	Ulcer index (mm)	Adhesion mucus content (μg/g wet glandular tissue)
A. No stress (unrestrained at 22 °C for 2 hours)
Tap water	2 (7)	0.03 ± 0.02	391 ± 39
Quit nicotine	3 (8)	0.04 ± 0.02	278 ± 29a
Quit nicotine + NO (chronic)	2 (7)	0.04 ± 0.03	386 ± 37
B. Stress (restrained at 4 °C for 2 hours)
Tap water	8 (8)c	6.2 ± 0.7d	190 ± 18d
Quit nicotine	8 (8)c	9.0 ± 0.9ad	142 ± 16c
Quit nicotine + NO (chronic)	7 (7)b	5.8 ± 0.8d	210 ± 19d

Values are mean ± SD. Number of rats in each group is shown in parentheses. Lesions: Only petechiae in stomach were seen with non-stressed condition. Both petechiae and haemorrhagic ulcer in stomach were observed in stressed condition. Tap water: Rats drank water as control. Quit nicotine: Rats drank nicotine (50 µg/ml) for 20 days, then, nicotine was replaced by water for another 10 days. Quit nicotine + NO (chronic): Rats drank nicotine (50 µg/ml) for 20 days, then, nicotine was replaced by water, and rats were given NO donor three times daily by oral gavages for 10 days before experiment.

^aP < 0.05 when compared to its own tap water control in A or B.

^bP < 0.05,

^cP < 0.01,

^dP < 0.001 when compared to the corresponding control in A.

Table 3 Change in mucosal MPO activity after nicotine intake and nitric oxide donor (NO) treatment

	Tap water + no stress	Tap water + stress	Nicotine + stress	Nicotine + stress + NO (acute)	Quit nicotine + stress	Quit nicotine +stress + NO (chronic)
MPO (u/g protein):	6.3 ± 0.7	9.3 ± 1.1a	9.1 ± 1.0a	7.9 ± 0.9	9.4 ± 1.2a	5.7 ± 0.9b

Values are mean ± SD. Each group had 8 rats. Stress: restrained at 4 °C for 2 hours. Tap water: Rats drank water (control). Nicotine: Rats drank nicotine 50 μg/ml for 20 days. Quit nicotine: Rats drank nicotine (50 µg/ml) for 20 days, then, nicotine was replaced by water for another 10 days. NO (acute): Rats drank nicotine (50 µg/ml) for 20 days, the rats were then given NO donor 60 and 10 min by oral gavages before stress. NO (chronic): Rats drank nicotine (50 µg/ml) for 20 days, then, nicotine was replaced by water, the rats were given NO donor three times daily by oral gavages for 10 days before experiment.

^aP < 0.05 vs its own corresponding group in tap water + no stress control.

^bP < 0.05 vs its own corresponding group in tap water + stress control.