No abstract

The discovery of hormone leptin has led to better understanding of the energy balance control. In addition to its effects on food intake and energy expenditure, leptin has now been implicated as a mediator of diverse physiological functions. Recently, leptin has been cloned in several domestic species. The sequence similarity suggests a common function or mechanism of this peptide hormone across species. Leptin receptors are expressed in most of tissues, which is consistent with the multiplicity of leptin functions. The main goal of this review was to summarize knowledge about effect of leptin on physiology of farm animals. Experiments point to a stimulatory action of leptin on growth hormone (GH) secretion, normal growth and development of the brain. Surprisingly, leptin is synthesized at a high rate in placenta and may function as a growth factor for fetus, signalling the nutritional status from the mother to her offspring. Maturation of reproductive system can be stimulated by leptin administration. Morphological and hormonal changes, consistent with a major role of leptin in the reproductive system, have also been described, including the stimulation of the release of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin. Leptin has a substantial effect on food intake and feeding behaviour in animals. Administration of leptin reduces food intake. Its level decrease within hours after initiation of fasting. Leptin also serves as a mediator of the adaptation to fasting, and this role may be the primary function for which was the molecule evolved.

There seems to be general agreement that oxidative stress is involved in many pathological conditions including Parkinson’s, Alzheimer’s, and other neurodegenerative diseases, and overall aging. Cerium oxide nanoparticles, also known as nanoceria (CeO2–NPs), have shown promise as catalytic antioxidants, based on their ability to switch between Ce3+ and Ce4+ valence states. In the present work we have synthesized and characterized CeO2–NPs, examined the effect of CeO2–NPs on amyloidogenesis of insulin, and analyzed the impact of CeO2–NPs on oxidative stress and biocompatibility in vitro in three types of invasive cancer cells, and in vivo in the preclinical model of the chorioallantoic membrane (CAM) of quail embryos. The different experimental techniques revealed a high stability and homogeneity of the “naked” CeO2–NPs synthesized by precipitation from a reversal microemulsion. The CeO2–NPs were 5–6 nm in diameter (TEM) and monodispersed and have a ζ +46.9 mV ζ potential in Milli-Q water. We demonstrated for the first time that CeO2–NPs affect insulin fibrillation in a dose-dependent manner. The inhibiting, IC50, and disassembling, DC50, concentrations were calculated to be ∼100 ± 3.5 and ∼200 ± 5.5 μg/mL, respectively. Furthermore, CeO2–NPs demonstrated reliable biocompatibility and sufficient uptake by glioma and breast cancer cells. The presence of a high concentration of CeO2–NPs within the cells resulted only in local changes in metabolic activity and generation of oxidative stress at a low level. Moreover, high biocompatibility with CeO2–NPs was shown in vivo in the CAM.