High fat programming induces glucose intolerance in weanling Wistar rats

We sought to determine whether maintenance on a high fat diet during defined periods of gestation and lactation induced glucose intolerance in weanling Wistar rats or affected food intake, weight, and glucose concentrations in mothers. Experimental groups comprised mothers and their weanling offspring maintained on a high fat diet during gestation and lactation (HFGL), during gestation only (HFG), or during lactation only (HFL). Maternal food intake, body weight, and fasting blood glucose concentrations were determined during lactation. Glucose tolerance was measured in the three-week-old weanling offspring. After overnight fasting, oral glucose tolerance tests were performed in the weanlings. Glucose was collected at (0), 10, 15, 30 and 60 min. HFGL and HFL weanlings had greater glucose concentrations compared to control weanlings at 10, 15, 30 and 60 min. For HFG weanlings, greater glucose concentrations were only found at 30 min, which normalized at 60 min. In all of the experimental groups, the highest glucose concentrations were demonstrated at 30 min, whereas the peak was achieved at 15 min in the control weanlings. Overt glucose intolerance was induced in weanlings maintained on a high fat diet throughout both gestation and lactation or throughout lactation only. Further, weanlings maintained on a high fat diet solely throughout gestation displayed milder glucose intolerance. Developmental programming with a high fat diet during defined periods of gestation and lactation induces glucose intolerance in weanling rats.

Islet cell response in the neonatal rat after exposure to a high-fat diet during pregnancy

Although pancreatic beta-cells are capable of adapting their mass in response to insulin requirements, evidence has shown that a dietary insult could compromise this ability. Fetal malnutrition has been linked to low birth weight and the development of type 2 diabetes later in life, while reduced beta-cell mass has been reported in adult rats fed a high-fat diet (HFD). Reported here are the effects of exposure to a HFD, during different periods of gestation, on neonatal rat weight and beta- and alpha-cell development. The experimental groups were composed of neonatal offspring obtained from Wistar rats fed a high-fat (40% as energy) diet for either the first (HF1), second (HF2), or third (HF3) week, or all three (HF1-3) weeks of gestation. Neonatal weights and circulating glucose and insulin concentrations were measured on postnatal day 1, after which the pancreata were excised and processed for histological immunocytochemical examination and image analysis. HF1 and HF2 neonates were hypoglycemic, whereas HF1-3 neonates were hyperglycemic. Low birth weights were observed only in HF1 neonates. No significant differences were detected in the circulating insulin concentrations in the neonates, although beta-cell volume and numbers were reduced in HF1-3 neonates. beta-cell numbers also declined in HF1 and HF3 neonates. alpha-cell volume, number and size were, however, increased in HF1-3 neonates. alpha-cell size was also increased in HF1 and HF3 neonates. In neonates, exposure to a maternal HFD throughout gestation was found to have the most adverse effect on beta-cell development and resulted in hyperglycemia.

Transcription factors, pancreatic development, and β-cell maintenance

Transcription factors play an important role during pancreatic development ensuring normal differentiation of the islet endocrine cells. In mature beta-cells, expression of specific transcription factors is essential in maintaining normal beta-cell function.

Immunolocalization of plasma kallikrein in human brain

Plasma kallikrein (PK) is a cofactor in blood coagulation and modulates inflammation through the release of bradykinin. Previously it was believed that plasma prekallikrein (PPK), the precursor of PK and a member of the serine protease superfamily, was synthesized exclusively by hepatocytes and secreted into circulation. However, recent studies show that the human brain contains a high level of PPK mRNA. In this study we sought to determine which areas of the brain express PK. Tissue from the spinal cord and 13 different regions of the human brain were collected at autopsy within 24h from death. Sections were probed using polyclonal antibodies (characterized by Western blotting) specific for PK. PK concentrations in extracts of these tissues were measured by ELISA. Immunolabeling of PK was observed in the cell bodies of the neurons of the hypothalamus, thalamus, spinal cord, cerebral cortex and brainstem. Positive PK immuno-reactivity was also demonstrated in the cytoplasm of the ependymal cells in sections of the hypothalamus and spinal cord. In addition, some fibre tracts of the pons, medulla and hippocampus as well as secretory cells of the pituitary gland also labeled. No immunoreactive PK was visualized in the choroid plexus or cerebellum. Our data demonstrate the cellular localization of PK in human brain. This work is supported by other studies that demonstrate PK mRNA in human heart, lung, trachea and brain. The cellular distribution of PK and kinin receptors in specific brain areas suggests a role for PK in the nervous system.