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To investigate the protective effects of berberine on ethanol-induced gastric ulcer in mice.Gastric ulcers were induced by oral ingestion of ethanol. Nitric oxide (NO) content was measured, and mRNA expression of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) were analyzed by reverse transcription-polymerase chain reaction (RT-PCR).The ulcer index (UI) at 1 h, 2 h, 3 h and 6 h after oral administration of ethanol was 23.8+/-1.4, 23.3+/-2.2, 22.3+/-1.2 and 20.8+/-1.1, respectively. The UI in the berberine-treated groups (5 mg/kg and 50 mg/kg) was less than the control group. The content of NO in the control group was 73.3+/-7.3 microL/L, 94.0+/-9.2 microL/L, 109.6+/-6.4 microL/L and 138.2+/-10.2 microL/L in gastric juice and 5.8+/-1.1 micromol/g protein, 8.3+/-1.1 micromol/g protein, 9.8+/-1.1 micromol/g protein and 11.9+/-1.2 micromol/g protein in gastric tissue at 1 h, 2 h, 3 h and 6 h, respectively, after the oral administration of ethanol. The content of NO in the berberine-treated groups (5 mg/kg and 50 mg/kg) was higher than the control group at 1 h after the oral administration of ethanol (P0.05), and was lower at 6 h (P0.05). Analysis by RT-PCR showed that expression of eNOS was inhibited but iNOS expression was enhanced by ethanol. However, the expression of eNOS could be enhanced and iNOS expression could be inhibited by berberine (P0.01).Berberine could significantly protect gastric mucosa from damage by ethanol. This effect may be related to the increased expression of eNOS mRNA and inhibited expression of iNOS mRNA.

To further investigate the action mechanisms of berberine (Ber), and assess the effects of Ber on the in vitro formation of cGMP and cAMP in the isolated rabbit corpus cavernosum.Isolated segments of the rabbit corpus cavernosum were exposed to different concentrations of Ber, and, the dosage-dependent accumulations of cGMP and cAMP were determined in the tissue samples by means of 125I radioimmunoassay. Responses of the isolated tissue preparations to Ber were compared with those obtained with the reference compound sildenafil (Sil).Ber increased cGMP concentrations directly (P0.05). In the presence of sodium nitroprusside (SNP), a stimulatory agent of cGMP, both Ber and Sil increased cGMP with increasing dosage (P0.01), the EC, values being 1.32 and 0.67 micromol/L respectively. With the same concentration, neither Ber nor Sil influenced the cAMP level significantly (P0.05). In the presence of PGE1, a stimulator of cAMP, Ber and Sil also raised the cAMP level concentration (P0.01 ), the EC, values being 4.90 (Ber) and 6.53 (Sil) micromol/L respectively.Ber can increase cGMP and cAMP concentrations in the corpus cavernosum smooth muscles, which may contribute to its action of relaxing corpus cavernosum smooth muscles.