Flow cytometry as a sensitive tool to assess testicular damage in rat

The aim of this study was to compare results obtained by flow cytometry (FC M) with those obtained from testicular histopathology with regard to testic ular damage following acute exposure of adult rats to the known testicular toxicant, methoxyacetic acid (MAA). Special emphasis was given to defining the sensitivity of three-parameter FCM compared with testicular histopathol ogy. Furthermore, the effect on the male reproductive system of a single or al dose of MAA was evaluated with traditional methods, e.g. testicular sper m head counts, and organ weights. Adult, male Han/Wistar rats were randomly assigned to four groups of ten animals to be treated with a single dose of 0, 65, 325 and 650 mg MAA/kg body wt. (p.o., gavage). The animals were kil led 2 days after treatment, and testicular and epididymal weights were reco rded. One testis and the corresponding epididymis were used for histopathol ogy. The other testis was used partly to determine sonication-resistant, te sticular sperm-head counts (SHC), and partly for enzymatic digestion follow ed by FCM. The results obtained in this study are in agreement with the lit erature, and show that, in the adult male rat, 2 days after administering a single oral dose of MAA, specific depletion of spermatocytes is evident. D etectable testicular effects were produced by the high (650 mg/kg body wt.) and mid (325 mg/kg body wt.) doses, whilst the low dose (65 mg/kg body wt. ) did not produce any noticeable effect. There was a strong correlation bet ween results obtained by FCM and those obtained by testicular histopatholog y, and no difference in sensitivity between the two methods was observed. T n summary, three-parameter FCM represents a sensitive and reliable method f or the detection of testicular injury in the rat. It requires only small am ounts of tissue, and the sensitivity was shown to be similar to that of his topathology. Moreover, FCM has the advantages of being quick and objective, which permits large numbers of cells to be analysed. The potential use of this method as a fast screening tool for testicular toxicity in routine tox icology studies should be considered.