Constitutive and heat-shock induced expression of Hsp70 mRNA during chicken testicular development and regression.

The constitutive and heat shock induced expression of Hsp70 mRNA was investigated in normal adult chicken testis and in adult testis after testicular regression induced by diethylstilbestrol (DES) treatment. In addition to the canonical form of Hsp70 mRNA, we have detected transcripts with an extended 5'UTR and transcripts containing, in the 5'UTR, sequences of the 18S ribosomal RNA. Hsp70 was expressed in unstressed male gonads in adult and regressed testis, being the expression much lower in regressed testis. Upon heat shock at 44 degrees C or 46 degrees C, Hsp70 was highly induced in both tissues. However, when testicular seminiferous tubules were incubated at the chicken internal temperature of 39 degrees C, no induction of Hsp70 was observed in mature testis, while the expression markedly increased in regressed testis. Induction at 39 degrees C was completely inhibited in the presence of 6 mM aspirin. Aspirin in the range 3-10 mM decreases the expression of Hsp70 in unstressed and stressed testicular cells, in striking contrast with the effect observed in other tissues as liver. These data suggest that the expression of Hsp70 is regulated in a specific manner in chicken testis and particularly in the male gonad undergoing regression.