Immunoreactivity for calretininin interneurons of the hippocampal CA1 field and dentate gyrus in adult rats after administration of habanero peppers (Capsicum chinense Jacq.).

Calretinin (CR), a calcium-binding protein from EF-hand family, is localised in non-pyramidal GABA-ergic interneurons of the hippocampus. CR takes part in maintaining calcium binding homeostasis, which suggests its neuroprotective role. Hippocampal neurons contain membrane transient receptor potential vanilloid 1 (TRPV1) which binds to capsaicin (CAP) contained in habanero pepper fruits. Few in vivo studies have revealed the effect of CAP on interneurons containing CR. The aim of the present study was to investigate the CR immunoreac- tivity in interneurons of the hippocampal CA1 field and dentate gyrus (DG) in adult rats after intragastric admin- istration of the habanero pepper fruits. Wistar rats received a peanut oil - control group (C), and oil suspension of habanero pepper fruits at doses of 0.025 g dm/kg b.w. - group I and 0.08 g dm/kg b.w. - group II for 28 days. After euthanasia, the brains were collected and embedded in paraffin blocks using a routine histological tech- nique. Frontal hippocampal sections were immunohistochemically stained for CR by using a peroxidase-antiper- oxidase method. CR immunoreactive (CR-IR) interneurons were morphologically and morphometrically ana- lyzed under a light microscope. The results showed similar shapes and distribution of cells in both areas of the brain in group C and I of animals. However, CR-IR interneurons in the hippocampal CA1 field and in DG were occasionally observed in the group II of rats. The results of morphometric studies did not reveal statistically significant differences in the surface area and shape index of cells between examined brain regions from groups I and II compared to group C. Only in group II of rats, an increase in the digital immunostaining intensity of CR-IR interneurons was found in DG. Low number of CR-IR interneurons in the hippocampal CA1 field and in the DG, under the influence of a large dose of habanero pepper fruits containing CAP, may be caused by the activation of TRPV1 receptors and the increase in Ca2+ ions in these cells. This phenomenon may ultimately lead to neuronal death and may disturb neuronal conduction.

Systemic and local effects of intragastric administration of the habanero fruit (Capsicum chinense Jacquin c.v.) in rats.

The fruits of the habanero plant (Capsicum chinense Jacq.) are commonly used as spices. Their exceptionally hot flavour is the result of the substantial content of capsaicin that has among others the anticancer action. The experiments assess the impact of intragastric administration of a suspension of dried matter (dm) habanero fruit in peanut oil on the state of the digestive tract and parenchymal organs of rats. Habanero fruit with three different doses (0.08, 0.05 and 0.025 g of dry matter (d.m.) habanero fruit/kg b.w.) in 2 equal doses every 12 hours during 28 days was administered intragastrically in male rats. In day 8, 15 and 29 blood proofs were obtained to measure hematological parameters and alanine aminotransferase (ALT), aspartate aminotransferase (AST) activity, total bilirubin (BIL), total cholesterol (CHOL), glucose (GLUC), urea (U), and creatinine (CREA) content. Internal organs of rats were examined anatomopathologically. Between the study groups and control group there were no statistically significant differences in studied parameters. Post-mortem examinations as well as histological findings showed no pathological changes in the organs of rats. The study demonstrated a high level safety of the fruit habanero (Capsicum chinense Jacq.) administration in rats. There were no hematological, biochemical or post-mortem changes at doses that due to the amount of capsaicin can exhibit antitumor properties.