Cold Ischemia Time Influences Spermatogenesis in a Testicular Ischemia/Reperfusion Injury Model

Postnatal testicular development in the Chinchilla rabbit

The Chinchilla rabbit is a breed with high commercial value and nowadays is increasingly used in various fields of biomedical research, however, its postnatal reproductive biology has been little studied. The aim of the present study was to investigate the postnatal development of the testis in this rabbit breed to determine both the proliferative periods and apoptosis. 30 rabbits aged 3-100 days old were used in the study. Determination of the period of differentiation of gonocytes to spermatogonia (50dpp), the periods of proliferation and apoptosis of their cells, as well as the beginning of spermatogenesis (60dpp) and the different stages of the seminiferous epithelium cycle were made. We found that these testicular developments were closer to that of humans when compared with rats, a species commonly employed in reproductive research. On comparing these results with those obtained from other breeds, there are clear differences favoring the use of this species as a research model in the field of male reproductive biology.

Renal protection from prolonged cold ischemia and warm reperfusion in hibernating squirrels

BACKGROUND

We have previously shown that cold ischemia (CI) results in massive increases in caspase-3 activity, tubular apoptosis, and brush border injury (BBI) in mouse kidneys. During hibernation, the 13-lined ground squirrel (GS) cycles through repeated CI during torpor, followed by warm ischemia/reperfusion (WI) during interbout arousal (IBA). We sought to determine whether CI and WI during hibernation caused caspase-3 activation, tubular apoptosis, acute tubular necrosis, or BBI, and reduced renal function. We also determined whether protection was dependent on the stage of hibernation.

METHODS

Radiotelemeters were implanted in 1-year-old GS, and core body temperature was remotely monitored. GS kidneys at various stages of hibernation were subjected to ex vivo CI.

RESULTS

Tubular apoptosis was not detected and caspase-3-like activity was not different between hibernating and summer kidneys. Despite prolonged CI followed by WI and reperfusion, acute tubular necrosis and apoptosis did not occur in hibernating kidneys. BBI was absent in torpid kidneys but significantly increased in IBA kidneys and associated with an increase in caspase-3-like activity, suggesting that IBA kidneys are more susceptible to injury than summer or torpid kidneys. Renal function and urine concentrating ability diminished during torpor but returned during IBA.

CONCLUSIONS

Despite BBI, IBA kidneys clear serum creatinine and concentrate urine. Kidneys from both summer and hibernating animals tolerated ex vivo CI, confirming that protection from apoptotic and necrotic cell death is independent of the stage of hibernation. An understanding of how renal protection occurs during hibernation may help in understanding the pathophysiology of delayed graft function.