DIFFERENTIAL REGULATION OF CYCLIC ADENOSINE-3',5'-MONOPHOSPHATE (CAMP) RESPONSE ELEMENT-BINDING PROTEIN AND CAMP RESPONSE ELEMENT MODULATORMESSENGER-RIBONUCLEIC-ACID TRANSCRIPTS BY FOLLICLE-STIMULATING-HORMONE AND ANDROGEN IN THE ADULT-RAT TESTIS

Hormonal regulation of the expression of mRNA transcripts for cAMP res ponse element-binding protein (CREB) and cAMP response element modulat or (CREM) during spermatogenesis was studied in the adult rat testis. Northern analysis of CREB and CREM identified two mRNA transcripts for CREM (2.4 and 1.6 kb) and one transcript for CREB (2.0 kb). Analysis of mRNAs from isolated testicular cells by reverse transcriptase polym erase chain reaction (RT/PCR) showed that CREM mRNAs were expressed by the germ cells but not the Sertoli or interstitial cells, whereas CRE B mRNA was located in germ cells, Sertoli cells, and interstitial cell s. RNA was isolated and analyzed from the testes of 1) rats treated fo r 24 h with FSH, 2) rats in which androgen withdrawal had been induced by ethane dimethane sulphonate (EDS) treatment 6 days earlier (EDS-tr eated), 3) EDS-treated rats supplemented with testosterone (EDS + T), or 4) intratesticular administration of dibutyryl cAMP (dbcAMP) in the preceding 24 h. CREM mRNA transcript expression was found to be decre ased after all of these treatments in samples from intact testis and f rom isolated cells. Expression of the CREB transcript was also decreas ed by EDS-induced androgen withdrawal, but not by FSH or EDS + T. In s itu hybridization of paraffin-embedded testis sections probed with dig oxigenin-labeled riboprobes confirmed the localization of CREB and CRE M mRNA to the same cell types as found with RT/PCR. No stage-dependent expression of CREM mRNA transcripts could be observed. Hybridization of the CREB probe was highest around the base of stage VII-VIII tubule s, and this was shown to be androgen-dependent. The data presented sug gest that regulation of the expression of CRE-binding protein mRNAs in Sertoli and germ cells during spermatogenesis is dependent on both an drogen and FSH. However, the effects of androgen or FSH on the regulat ion of CRE-binding protein mRNAs are different.