Biochemical characterization of epidermal growth-factor receptor in Syrian hamster buccal pouch

Strychnos nux-vomica extract and its ultra-high dilution reduce voluntary ethanol intake in rats

OBJECTIVES

To see whether Strychnos nux-vomica extract (mother tincture [MT]), its potency Nux 30c, and its principal alkaloid, strychnine, could reduce voluntary ethanol intake in rats. To analyze the solution structure of Nux MT, Nux 30c, 90% ethanol, and ethanol 30c by means of electronic (ES) and nuclear nuclear magnetic resonance (NMR) spectra.

DESIGN

Potentially alcoholic rats were first given 20% ethanol and then kept on a two-choice bottle, one with 20% ethanol and another with tap water. These rats were given the following oral treatments for 15 days: group 1, control; group 2, strychnine at 0.36 mg/kg per day; group 3, ethanolic extract of S. nux-vomica seeds (Nux MT) at 3.6 mg/kg per day; and group 4, Nux 30c at 0.05 mL/d per rat. Nux 30c was prepared by successive dilution of Nux MT and 90% ethanol (1:100) and sonication at 20 kHz for 30 seconds in 30 steps.

RESULTS

Both Nux MT and Nux 30c significantly reduced ethanol intake and increased water intake in rats. ES of two dilutions of Nux MT and Nux 30c showed intersections at more than one point suggesting existence of molecular complexes. ES of Nux MT in CCl4 showed a red shift when 90% ethanol was added indicating molecular complexation and charge transfer interaction between ethanol and Nux compounds. NMR spectra of Nux MT, 90% ethanol, ethanol 30c, and Nux 30c indicated a change in solution structure of the medium (90% ethanol) of Nux 30c.

CONCLUSION

Nux MT and Nux 30c could reduce ethanol intake in rats. The altered solution structure of Nux 30c is thought to mimic Nux MT and produce ethanol aversion in rats.

Effects of in vivo treatments of nicotine and benzo[a]pyrene on the epidermal growth factor receptor in hamster buccal pouch

This study was conducted to investigate the effects of two major ingredients in cigarette smoke, benzo-alpha-pyrene (BP) and nicotine (Nic), on epidermal growth factor (EGF) receptor in hamster buccal pouch. Adult male Syrian hamsters were treated by apically swabbing the buccal pouch with mineral oil (Control), 0.5 microgram/ml of BP, Nic or BP+Nic in mineral oil, twice a day, 5 days a week for 4 weeks. The BP+Nic treatment resulted in a significant reduction of submandibular gland (SG) EGF (Control vs. BP+Nic, 6.93 +/- 1.31 vs. 4.77 +/- 0.26* ng/g wet tissue, mean +/- S.D., n=5,*P < 0.05). Treatment with BP or Nic also caused a reduction, although not statistically significant, of EGF in SG extract. For the receptor study, all treatments significantly increased [125I]EGF binding to membrane preparations of buccal pouch as compared to Control (Control, BP, Nic, BP+Nic; 12.2 +/- 0.9, 20.5 +/- 2.2*, 17.0 +/- 1.3*, 21.2 +/= 1.6* fmol/mg prot. (mean +/- S.E.M.), n=5, P < 0.05). Scatchard analysis revealed that the higher EGF binding to the BP+Nic-treated sample was due to the higher number of receptors, but not higher affinity. Data from protein kinase study indicate that EGF stimulated phosphorylation of 170- and 150-kDa proteins in buccal membrane preparations. Treatment of BP+Nic resulted in reductions in EGF-stimulated phosphorylation of 170- and 150-kDa proteins by 19 and 72%, respectively. The present study has established an animal model which will benefit investigation of the mechanism by which tobacco alters the EGF receptor in oral buccal mucosa.

Transforming growth factor-alpha and epidermal growth factor in hamster tissues: biochemical and immunohistochemical studies

In Syrian golden hamster kidneys and submaxillary glands, the levels of EGF, determined by radioimmunoassay, were much lower than in the same organs of two other rodent species, mouse and rat. In submaxillary glands, the EGF/TGF-alpha receptor-binding activities were also much lower in hamster than in mouse and rat. In contrast, the TGF-alpha content of hamster kidneys, determined by radioimmunoassay, was higher than in the kidneys of the other animals, as was the EGF/TGF-alpha receptor-binding activity. Using immunohistochemistry, the TGF-alpha immunoreactivity in hamster kidneys was localized both in proximal and distal tubules with the exception of the macula densa area. The levels of TGF-alpha in the submaxillary glands were very low in all the animals tested. Hamster kidney extracts contained a specific immunoreactive protein with the M(r) and the N-terminal amino acid sequence (VVSHFNECPD) expected for mature hamster TGF-alpha. Western blot analysis of hamster renal solubilized membrane proteins using anti-EGF receptor antibodies revealed three immunoreactive protein bands of which one had the M(r) expected for the EGF/TGF-alpha receptor. The immunohistochemical pattern of this receptor in hamster kidneys proximal tubular cells was very similar to the other tested rodent species.