Assignment #4 - Article Review

Assignment # 4 - Article Review

Paper: Bobes, R. J., Castro, J. I., & Miranda, C. C. (2001). Insulin modifies the proliferation and function of chicken testis cells. Poultry Science, 80(5), 637-642

Paper can be retrieved from: http://ps.fass.org/content/80/5/637.full.pdf+html

Summary

As mentioned in the previous blogs, the main role of insulin is glucose homeostasis. However, it was also mentioned that insulin has several other roles such as stimulating lipogenesis, diminishing lipolysis, modulating transcription, and stimulating growth. 

Bobes et al. (2000) conducted an experiment to investigate whether insulin plays a role in the proliferation and the androgen production of chick testis cells since insulin is already present in the chick embryo. This is the first study to examine this. To see if insulin did in fact have an effect on chick testis cell proliferation and androgen production, Bobes et al. used testes from 18 day old chick embryos or newly hatched chicks. The testes were dissociated, the cells were pre-cultured and then cell suspensions were made and each were exposed to varying concentrations of insulin and human chorionic gonadotropin (hCG) for varying amounts of time. 

                                          Figure 1:  chick embryo at 18 days of development

Bobes et al. found that when incubated with insulin for one hour, the androgen production of the chick embryo testis cells was not directly affected. However, incubating the cells in insulin for an hour did modify how the cells responded to hCG in that it resulted in a slight but significant increase in androgen production. The opposite occurred when the concentration of insulin increased.  These results are shown in figure 1 of the paper.  On the other hand, the testes cells from the newly hatched chickens showed a large increase in the production of androgens (testosterone) with the addition of increasing dosages of insulin. These results are shown in figure 4.

Bobes et al. also found that insulin enhances the proliferation of embryonic cells by observing that insulin significantly increased the uptake of H-thymidine by testes cells as shown in figure 3 of the paper. 

In conclusion, the experiment shows that insulin does effect the proliferation and the androgen production of chick testis cells and that the stage of maturity affects the cells’ response to the hormone. It also demonstrates that insulin has a slight stimulatory on hCG-dependent androgen production in embryonic chick testis cells. 

Critique

Overall, the paper is well written. It is very easy to understand and is presented in an organized manner. The experiment is explained in a way that can be easily followed by the reader.  Also, the figures are very basic but effective at displaying the results of the experiment. I like that the paper did not include an overwhelming amount of statistical analysis. 

I would have liked a better explanation in the discussion as to why the embryo testes cells did not show an increase in the androgen production in the presence of insulin but the newly hatched chick testes cells did. Saying that sensitivity to insulin depends on stage of maturity seemed like an insufficient explanation.  

A little more background information in the introduction section would have aided in the understanding of the results obtained.

The results of the experiment did seem to support to the authors’ claims and it was interesting to read how the authors’ previous experiment tied in with the one conducted in this paper.

For future experiments, it is mentioned in the paper that while the results show that insulin does influence cell proliferation and androgen production of the chick testes cells, the mechanism of how this occurs needs further investigation. It would also be interesting to conduct this same experiment on another species to see if similar results are obtained.





*References can be accessed through links on pictures and citations.*