Influence of nutrition on male development and reproduction in Tribolium castaneum

Insect Models in Nutrition Research

Insects are the most diverse organisms on earth, accounting for ~80% of all animals. They are valuable as model organisms, particularly in the context of genetics, development, behavior, neurobiology and evolutionary biology. Compared to other laboratory animals, insects are advantageous because they are inexpensive to house and breed in large numbers, making them suitable for high-throughput testing. They also have a short life cycle, facilitating the analysis of generational effects, and they fulfil the 3R principle (replacement, reduction and refinement). Many insect genomes have now been sequenced, highlighting their genetic and physiological similarities with humans. These factors also make insects favorable as whole-animal high-throughput models in nutritional research. In this review, we discuss the impact of insect models in nutritional science, focusing on studies investigating the role of nutrition in metabolic diseases and aging/longevity. We also consider food toxicology and the use of insects to study the gut microbiome. The benefits of insects as models to study the relationship between nutrition and biological markers of fitness and longevity can be exploited to improve human health.

Inhibition of ghrelin signaling improves the reproductive phenotype of male ob/ob mouse

OBJECTIVE

To investigate whether ghrelin signaling is involved in the pathogenesis of male factor infertility induced by leptin deficiency.

DESIGN

Experimental study.

SETTING

University academic medical center.

ANIMAL(S)

Ten-week-old C57BL/6J mice and ob/ob mice.

INTERVENTION(S)

Western blotting, (quantitative) reverse transcription-polymerase chain reaction (qRT-PCR), immunohistochemistry, and in situ end labeling of fragmented DNA.

MAIN OUTCOME MEASURE(S)

Expression levels of ghrelin and its functional receptor growth hormone (GH) secretagogue receptor 1a (GHS-R1α) were examined by Western blotting and immunohistochemistry. Ob/ob mice were injected IP with specific GHS-R1α antagonist, and thereafter germ cell apoptosis and steroidogenic capability were assessed by TUNEL assay, (q) RT-PCR, and radioimmunoassay.

RESULT(S)

Expression of GHS-R1α and its endogenous ligand ghrelin was both up-regulated in ob/ob testis. Inhibition of the ghrelin pathway restored androgen synthesis, reduced germ cell apoptosis, and thereby resulted in improved sperm production in ob/ob mice.

CONCLUSION(S)

Ghrelin, as an antagonistic partner of leptin in the endocrinic/paracrine circuit, may be involved in the pathogenesis of male factor infertility induced by leptin deficiency.