Evidence of Aquaporin 4 Regulation by Thyroid Hormone During Mouse Brain Development and in Cultured Human Glioblastoma Multiforme Cells.

Accumulating evidence indicates that thyroid function and the thyroid hormones L-thyroxine (T4) and L-triiodothyronine (T3) are important factors contributing to the improvement of various pathologies of the central nervous system, including stroke, and various types of cancer, including glioblastoma multiforme (GBM). Low levels of T3 are correlated with the poorest outcome of post-stroke brain function, as well as an increased migration and proliferation of GBM tumor cells. Thyroid hormones are known to stimulate maturation and brain development. Aquaporin 4 (AQP4) is a key factor mediating the cell swelling and edema that occurs during ischemic stroke, and plays a potential role in the migration and proliferation of GBM tumor cells. In this study, as a possible therapeutic target for GBM, we investigated the potential role of T3 in the expression of AQP4 during different stages of mouse brain development. Pregnant mice at gestational day 18, or young animals at postnatal days 27 and 57, received injection of T3 (1 µg/g) or NaOH (0.02 N vehicle). The brains of mice sacrificed on postnatal days 0, 30, and 60 were perfused with 4% paraformaldehyde and sections were prepared for immunohistochemistry of AQP4. AQP4 immunofluorescence was measured in the mouse brains and human GBM cell lines. We found that distribution of AQP4 was localized in astrocytes of the periventricular, subpial, and cerebral parenchyma. Newborn mice treated with T3 showed a significant decrease in AQP4 immunoreactivity followed by an increased expression at P30 and a subsequent stabilization of aquaporin levels in adulthood. All GBM cell lines examined exhibited significantly lower AQP4 expression than cultured astrocytes. T3 treatment significantly downregulated AQP4 in GBM-95 cells but did not influence the rate of GBM cell migration measured 24 h after treatment initiation. Collectively, our results showed that AQP4 expression is developmentally regulated by T3 in astrocytes of the cerebral cortex of newborn and young mice, and is discretely downregulated in GBM cells. These findings indicate that higher concentrations of T3 thyroid hormone would be more suitable for reducing AQP4 in GBM tumorigenic cells, thereby resulting in better outcomes regarding the reduction of brain tumor cell migration and proliferation.

Toxicological, Antidiarrheal and Spasmolytic Activities of Solanum paniculatum.

Solanum paniculatum is popularly known as "jurubeba-verdadeira". In folk medicine, its roots, stems, and leaves are used as tonics, anti-inflammatories, carminatives, diuretics, and for gastrointestinal disorders. This species is listed in the Brazilian Pharmacopoeia and belongs to the "Relação Nacional de Plantas Medicinais de Interesse ao SUS". Based on folk medicine data of the Solanum genus, we decided to investigate whether the crude ethanol extract from S. paniculatum aerial parts presents toxicological, antidiarrheal, and spasmolytic activities. The crude ethanol extract from S. paniculatum aerial parts did not produce in vitro or in vivo toxicity and showed dose-dependent antidiarrheal activity, inhibiting equipotently both the defecation frequency (ED50 = 340.3 ± 35.1 mg/kg) and liquid stool formation (ED50 = 370.1 ± 19.4 mg/kg) in mice. Conversely, the crude ethanol extract from S. paniculatum aerial parts did not inhibit normal intestinal transit, even though it has shown a dose-dependent reduction of both the castor oil-induced intestinal transit (Emax = 36.9 ± 1.3 %, ED50 = 242.0 ± 8.6 mg/kg) and intestinal fluid content (Emax = 74.8 ± 2.4 %, ED50 = 328.9 ± 15.9 mg/kg). Additionally, the crude ethanol extract from S. paniculatum aerial parts was approximately 2-fold more potent in antagonizing the phasic contractions induced with histamine (IC50 = 63.7 ± 3.5 µg/mL) than carbachol 10(-6) M (IC50 = 129.3 ± 14.1 µg/mL). Therefore, we concluded that the crude ethanol extract from S. paniculatum aerial parts presents antidiarrheal activity in mice related to the inhibition of small intestinal motility and secretion as well as nonselective spasmolytic activity on the guinea pig ileum.

Antidiarrheal activity of Solanum asterophorum in mice

Several species of Solanum are used in folk medicine to treat diarrhea. Therefore, the aim of this study was to investigate and compare possible antidiarrheal activity of methanol extracts from roots (Sast-MeOH R) and leaves (Sast-MeOH L) of Solanum asterophorum Mart., Solanaceae, in mice. Sast-MeOH R was shown to significantly and dose-relatedly inhibit the frequency of both solid (ED50 309.6±28.5 mg/kg) and liquid (ED50 152.1±32.5 mg/kg) stools. Conversely, Sast-MeOH L significantly inhibited solid stool frequency only when dosed at 500 and 750 mg/kg (48.7±7.4 and 42.3±9.8 percent, respectively), but also significantly and dose-relatedly inhibited liquid stools (ED50 268.4±35.2 mg/kg). Thus, Sast-MeOH R was twice as potent as Sast-MeOH L in diarrhea inhibition. Neither extracts (when dosed up to 500 mg/kg) inhibited intestinal transit. However, both extracts significantly and dose-relatedly inhibited intestinal fluids, and Sast-MeOH R (ED50 38.3±10.4 mg/kg) was again twice as potent as Sast-MeOH L (ED50 78.6±6.4 mg/kg). Results suggest that antidiarrheal effects of Sast-MeOH R and Sast-MeOH L involve changes on intestinal secretion. In addition, active metabolites with antidiarrheal activity may be more concentrated in the roots of this species. However further studies are needed to elucidate the action mechanism involved in this activity.