OBJECTIVETo determine the O/W partition coefficient of geniposide in fructus gardeniae extract and investigate the absortion kinetics of geniposide in whole small intestine and different intestinal segments of rats.

METHODThe shake-flask method was employed to determine the O/W partition coefficient of geniposide; an in situ intestinal perfusion model was employed to investigate the absorptive kinetics of geniposide.

RESULTThe partition coefficient (P) of geniposide was 0.1077, logP was -0.9678; the absorptive rate constants (K) of geniposide at the concentration of 0.078, 0.311, 0.780 g x L(-1) were (0.130 +/- 0.007), (0.056 +/- 0.003), (0.031 +/- 0.006) h, respectively. The K of geniposide were (0.019 +/- 0.003), (0.015 +/- 0.002), (0.012 +/- 0.002) h at duodenum, jejunum, ileum, respectively.

CONCLUSIONAccording to the P and the logP, it could be indicated that the absorption of geniposide at small intestine was poor absorption; The absorption rate was increased with the decrease of the extract concentration; Their absorption was first-order process besides the passive diffusion mechanism, and facilitated diffusion and active transport may also take part in the transport process. Geniposide was absorbed at all smallintestinal segments of rats, but the duodenal absorption ratewas higher more than other section.

Animals ; Drugs, Chinese Herbal ; chemistry ; pharmacokinetics ; Gardenia ; chemistry ; Intestinal Absorption ; drug effects ; Intestines ; drug effects ; physiology ; Iridoids ; chemistry ; pharmacokinetics ; Kinetics ; Male ; Random Allocation ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo observe the influence of betahistine on the expression of histamine H3 receptor in the medial vestibular nucleus (MVN) following unilateral labyrinthectomy (UL).

METHODSFifty-six healthy guinea pigs were randomly divided into three groups:the sham-operated group (group I), the UL group[group II, and UL+betahistine (BET) group (group III)], BET was intraperitoneally injection at 2.17 mg×kg(-1)×d(-1) for 7 days. The expression of histamine H3 receptor was analyzed by immunohistochemistry at 1 day, 3 days and 7 days after UL.

RESULTSH3 receptors were presented in the MVN and the expression of histamine H3 receptor were increased significantly in the ipsilateral MVN at 1 and 3 days after UL(P < 0.05), the change turned into the normal value at 7 days(P > 0.05). In the UL+BET group, the intensity of histamine H3 receptor was lower than that in the UL at 1 day and 3 days(4.25 ± 0.71, 3.50 ± 0.92 vs 5.75 ± 0.71, 5.50 ± 0.93, P < 0.05). However, the changes turned into the normal values at 3 and 7 days (P > 0.05).

CONCLUSIONSThe early stage of the vestibular compensation process may be associated with the change of H3 receptor expression in MVN. In the UL+BET group the histamine H3 receptor recovered quickly.

Animals ; Betahistine ; metabolism ; Ear, Inner ; Guinea Pigs ; Otologic Surgical Procedures ; Receptors, Histamine H3 ; metabolism ; Vestibular Nuclei ; metabolism ; Vestibule, Labyrinth ; surgery