The effect of neonatal capsaicin treatment on gustatory behavior in the albino rat

Salivary cystatins influence ingestion of capsaicin-containing diets in the rat

Dietary capsaicin consumed by rats over several days induces cystatin-like substances in submandibular saliva. Yet the physiological role of these salivary proteins has not been thoroughly investigated. Salivary cystatins in the rat submandibular glands are known to be induced by chronic treatment with the sympathetic beta-agonist, isoproterenol. In the present study, the possible roles of the salivary proteins on food intake were examined by comparing consumption of a capsaicin-adulterated (0.05%) diet in rats with and without isoproterenol pretreatment (0.1 and 5.0 mg/kg, 5 days). Electrophoretic analysis performed prior to feeding trials revealed that the group pretreated with 5 mg/kg isoproterenol had large amounts of cystatin in the saliva compared with the group pretreated with 0.1 mg/kg isoproterenol and control group. The group treated with 5 mg/kg isoproterenol showed greater consumption of the capsaicin-adulterated diet than the other groups until the 3rd day of trials. Bilateral removal of the submandibular and sublingual glands neutralized the effects of isoproterenol. Induction of salivary cystatins by isoproterenol treatment was not mimicked by systemic and intragastric administration of capsaicin. These results suggest that cystatins are included in the salivary proteins induced by capsaicin and that they contribute to enhanced ingestion of the capsaicin diet. Induction of salivary cystatins may be triggered by irritation of the oral mucosa by capsaicin.

Cutaneous wounds produced by capsaicin treatment of newborn rats are due to trophic disturbances

The purpose of this study was to show that the occurrence of skin ulcers observed in animals neonatally treated with the neurotoxin capsaicin coincide with trophic disturbances. In addition, cutaneous lesions increased when self-grooming and scratching behaviors reached maturity. The temporal course of cephalic cutaneous wounds in neonatally capsaicin-treated rats was evaluated in animals wearing and not wearing plastic collars from postnatal day (P) 21 until P45. The collars were used to prevent self-grooming and scratching. Beginning on P21, capsaicin-treated rats under both conditions showed transient skin ulcers distributed throughout the head and neck regions. In the capsaicin-treated group without collars, lesions reached their greatest severity by P40, when self-grooming and scratching behaviors obtained adult characteristics. Furthermore, no lesions were detected after 25 days. In the capsaicin-treated rats that wore plastic collars, the widest distribution of skin lesions occurred on P55, after which time lesions vanished detection by 25 days. In this latter group, the cutaneous lesions were exacerbated when collars were removed. Data suggest that transient cutaneous wounds associated with neonatal capsaicin administration may be mediated via capsaicin-sensitive sensory neurons that are involved in trophic and regenerating neural mechanisms.

Ethanol consumption and taste preferences in C57BL/6ByJ and 129/J mice

Mice of the C57BL/6ByJ (B6) and 129/J (129) strains were offered different concentrations of taste solutions in 48-hr, two-bottle choice tests. In comparison with the 129 strain, the B6 strain had higher preferences for ethanol, sucrose, and citric acid. They had lower preferences for NaCl and similar preferences for capsaicin and quinine hydrochloride. These data are consistent with the hypothesis that the higher ethanol intake by B6 mice depends, in part, on higher hedonic attractiveness of its sweet taste component.