Dopamine D2 receptor antagonist counteracts hyperglycemia and insulin resistance in diet-induced obese male mice.

Obesity leads to insulin resistance (IR) and type 2 diabetes. In humans, low levels of the hormone prolactin (PRL) correlate with IR, adipose tissue (AT) dysfunction, and increased prevalence of T2D. In obese rats, PRL treatment promotes insulin sensitivity and reduces visceral AT adipocyte hypertrophy. Here, we tested whether elevating PRL levels with the prokinetic and antipsychotic drug sulpiride, an antagonist of dopamine D2 receptors, improves metabolism in high fat diet (HFD)-induced obese male mice. Sulpiride treatment (30 days) reduced hyperglycemia, IR, and the serum and pancreatic levels of triglycerides in obese mice, reduced visceral and subcutaneous AT adipocyte hypertrophy, normalized markers of visceral AT function (PRL receptor, Glut4, insulin receptor and Hif-1α), and increased glycogen stores in skeletal muscle. However, the effects of sulpiride reducing hyperglycemia were also observed in obese prolactin receptor null mice. We conclude that sulpiride reduces obesity-induced hyperglycemia by mechanisms that are independent of prolactin/prolactin receptor activity. These findings support the therapeutic potential of sulpiride against metabolic dysfunction in obesity.

The Diversity of Gut Microbiota at Weaning Is Altered in Prolactin Receptor-Null Mice.

Maternal milk supports offspring development by providing microbiota, macronutrients, micronutrients, immune factors, and hormones. The hormone prolactin (PRL) is an important milk component with protective effects against metabolic diseases. Because maternal milk regulates microbiota composition and adequate microbiota protect against the development of metabolic diseases, we aimed to investigate whether PRL/PRL receptor signaling regulates gut microbiota composition in newborn mice at weaning. 16SrRNA sequencing of feces and bioinformatics analysis was performed to evaluate gut microbiota in PRL receptor-null mice (Prlr-KO) at weaning (postnatal day 21). The normalized colon and cecal weights were higher and lower, respectively, in the Prlr-KO mice relative to the wild-type mice (Prlr-WT). Relative abundances (Simpson Evenness Index), phylogenetic diversity, and bacterial concentrations were lower in the Prlr-KO mice. Eleven bacteria species out of 470 differed between the Prlr-KO and Prlr-WT mice, with two genera (Anaerotruncus and Lachnospiraceae) related to metabolic disease development being the most common in the Prlr-KO mice. A higher metabolism of terpenoids and polyketides was predicted in the Prlr-KO mice compared to the Prlr-WT mice, and these metabolites had antimicrobial properties and were present in microbe-associated pathogenicity. We concluded that the absence of the PRL receptor altered gut microbiota, resulting in lower abundance and richness, which could contribute to metabolic disease development.

EGFR and p38MAPK Contribute to the Apoptotic Effect of the Recombinant Lectin from Tepary Bean (Phaseolus acutifolius) in Colon Cancer Cells.

Previous works showed that a Tepary bean lectin fraction (TBLF) induced apoptosis on colon cancer cells and inhibited early colonic tumorigenesis. One Tepary bean (TB) lectin was expressed in Pichia pastoris (rTBL-1), exhibiting similarities to one native lectin, where its molecular structure and in silico recognition of cancer-type N-glycoconjugates were confirmed. This work aimed to determine whether rTBL-1 retained its bioactive properties and if its apoptotic effect was related to EGFR pathways by studying its cytotoxic effect on colon cancer cells. Similar apoptotic effects of rTBL-1 with respect to TBLF were observed for cleaved PARP-1 and caspase 3, and cell cycle G0/G1 arrest and decreased S phase were observed for both treatments. Apoptosis induction on SW-480 cells was confirmed by testing HA2X, p53 phosphorylation, nuclear fragmentation, and apoptotic bodies. rTBL-1 increased EGFR phosphorylation but also its degradation by the lysosomal route. Phospho-p38 increased in a concentration- and time-dependent manner, matching apoptotic markers, and STAT1 showed activation after rTBL-1 treatment. The results show that part of the rTBL-1 mechanism of action is related to p38 MAPK signaling. Future work will focus further on the target molecules of this recombinant lectin against colon cancer.

Quantum Dot Labelling of Tepary Bean (Phaseolus acutifolius) Lectins by Microfluidics.

Lectins are bioactive proteins with the ability to recognize cell membrane carbohydrates in a specific way. Diverse plant lectins have shown diagnostic and therapeutic potential against cancer, and their cytotoxicity against transformed cells is mediated through the induction of apoptosis. Previous works have determined the cytotoxic activity of a Tepary bean (Phaseolus acutifolius) lectin fraction (TBLF) and its anti-tumorigenic effect on colon cancer. In this work, lectins from the TBLF were additionally purified by ionic-exchange chromatography. Two peaks with agglutination activity were obtained: one of them was named TBL-IE2 and showed a single protein band in two-dimensional electrophoresis; this one was thus selected for coupling to quantum dot (QD) nanoparticles by microfluidics (TBL-IE2-QD). The microfluidic method led to low sample usage, and resulted in homogeneous complexes, whose visualization was achieved using multiphoton and transmission electron microscopy. The average particle size (380 nm) and the average zeta potential (-18.51 mV) were determined. The cytotoxicity of the TBL-IE2 and TBL-IE2-QD was assayed on HT-29 colon cancer cells, showing no differences between them (p ≤ 0.05), where the LC50 values were 1.0 × 10-3 and 1.7 × 10-3 mg/mL, respectively. The microfluidic technique allowed control of the coupling between the QD and the protein, substantially improving the labelling process, providing a rapid and efficient method that enabled the traceability of lectins. Future studies will focus on the potential use of the QD-labelled lectin to recognize tumor tissues.