Reply: environmental estrogens and sperm function

Sebastiano Andò

Department of Cell Biology,Faculty of Farmacy,University of Calabria,Arcavacata di Rende-Cosenza, 87030, Italy e-mail: sebastiano{at}ando.unical.it

Dear Sir,

The mechanism of the induction of sperm capacitation remains enigmatic and many paracrine or endocrine candidates have been proposed.

As to the question raised by the authors mentioned in our paper (Adeoya-Osiguwa et al., 2003Go), we would like to point out that the most important finding in our paper (Aquila et al., 2003Go) is the evidence that autonomous estrogen production through enzymatically active P450 aromatase in human ejaculated spermatozoa may trigger the events occurring in capacitation and afterwards in acrosome reaction. In other words, according to our study it emerges that estradiol (E2) and aromatizable androgens per se may prime the events of sperm capacitation in vitro without the concomitant presence of capacitating factors (CaCl2, BSA, HCO3–, etc).

This priming effect of estrogen by some mechanism is reinforced by the experiments of the authors who observed that E2 and environmental estrogens, in the presence of still uncapacitated spermatozoa, significantly accelerated ‘the rate of capacitation and then promoting "overcapacitation" in at least some of the cells, resulting in the acrosome reaction’ (Adeoya-Osiguwa et al., 2003Go). To discriminate the direct effect of steroids tested on ejaculated spermatozoa, we compared the effect elicited by the different steroids either in the presence or total absence of capacitating factors. As a result, we would consider the assumption of the authors that the ‘only physiologically sound approach would have been to use a capacitating medium for all investigations and look for steroid-induced acceleration of capacitation-dependent parameters’ somewhat biased. Therefore, we suggest that to evaluate the influence of the aromatizable and not-aromatizable substrates per se on ejaculated spermatozoa they are prepared in uncapacitating medium, as we did in the following way: after liquefaction, normal semen samples were pooled and subjected to centrifugation (800 g) The pellet is washed twice with uncapacitating medium (Earle’s balanced salt solution medium without CaCl2, BSA, sodium pyruvate, sodium lactate, sodium bicarbonate or other capacitating factors) and then resuspended in the same medium in the presence (experimental) or absence (control) of different amounts of the E2 or aromatizable or not aromatizable substrates (as we reported in our paper).

Under these experimental conditions we have obtained reproducible results of the acrosin activity (µIU acrosin/106sperm), consistent with the Figure 6 in our paper (Aquila et al., 2003Go).

On the basis of these observations, it is not substantially relevant that we reported in our paper, due to a misquote, that ‘further support for this assumption is raised by the recent finding that estradiol stimulates capacitation in uncapacitating medium’ instead of ‘in uncapacitated sperm’ (Adeoya-Osiguwa et al., 2003Go). In the same vein it would be productive for any possible collaboration between our groups if the authors, in order to sustain their arguments, could be motivated to check the influence of estrogens or aromatizable androgens on ejaculated spermatozoa maintained in the experimental conditions reported in our study.

References

Adeoya-Osiguwa SA, Markoulaki S, Pocock V, Milligan SR and Fraser LR (2003) 17{beta}-Estradiol and environmental estrogens significantly affect mammalian sperm function. Hum Reprod 18,100–107.[Abstract/Free Full Text]

Aquila S, Sisci D, Gentile M, Carpino A, Middea E, Catalano S, Rago V and Andò S (2003) Towards a physiological role for cytochrome P450 aromatase in ejaculated human sperm. Hum Reprod 18,1650–1659.[Abstract/Free Full Text]





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