title: Temporal gene expression is restored concomitantly with germ cells in the experimentally regressed rat testis.
abstract: The present study was designed to examine the effect of hypophysectomy and subsequent testosterone administration on germ cell numbers and germ cell- and Sertoli cell-specific mRNA levels in adult rats. Rats were hypophysectomized and 4 weeks later received 24-cm testosterone-containing polydimethylsiloxane (PDS) implants. Sham-hypophysectomized rats received an empty PDS implant. At 0 and 3 days, and at 1, 2, 4, and 8 weeks, rats were killed. One testis from each rat (n = 4/group) was used to prepare total RNA; the other testis was used to enumerate stage VII-VIII germ cells. cDNA probes for germ cell and Sertoli cell products were used to monitor germ cell- and Sertoli cell-specific mRNAs on Northern blots. Four weeks after hypophysectomy (0 days), preleptotene and pachytene spermatocytes and round and elongating spermatids were reduced in number to 54%, 12%, 1%, and 0%, respectively, of the control values. Testosterone administration caused a time-dependent increase in germ cell numbers; after 8 weeks of testosterone treatment, preleptotene and pachytene spermatocytes and round and elongating spermatids were 75%, 79%, 74%, and 22%, respectively, of control values. Lactate dehydrogenase-C, phosphoglycerate kinase-2, protamine-1, and sulfated glycoprotein-2 mRNA levels (on a per micrograms RNA basis) were 34%, 34%, less than 1%, and 580% of control values, respectively, 4 weeks after hypophysectomy and 79%, 87%, 61%, and 192% of control values, respectively, after 8 weeks of testosterone treatment. Pachytene spermatocyte and round spermatid numbers increased, while Sertoli cell sulfated glycoprotein-2 mRNA levels decreased, with respect to 4 week hypophysectomy values, as early as 3 days after implantation of testosterone capsules. In contrast, germ cell (lactate dehydrogenase-C, phosphoglycerate kinase-2, and protamine-1) mRNA levels increased to the greatest extent between 1-4 weeks after the start of testosterone treatment and, after a short lag period, reflected increases in germ cell type and number. The results indicate that cell-specific mRNAs appear concomitantly with germ cell reappearance in a time-dependent manner in the testes of testosterone-treated hypophysectomized adult rats.
authors.affiliation: Department of Pediatrics, McGill-Montreal Children's Hospital Research Institute, Quebec, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: Trasler
authors.forename: A A
authors.initials: AA
authors.lastname: Alcivar
authors.forename: C A
authors.initials: CA
authors.lastname: Awoniyi
authors.forename: R
authors.initials: R
authors.lastname: Santulli
authors.forename: B R
authors.initials: BR
authors.lastname: Zirkin
authors.forename: N B
authors.initials: NB
authors.lastname: Hecht
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D051152:Clusterin; D004343:Drug Implants; D015870:Gene Expression; D006023:Glycoproteins / Q000235:genetics; D007016:Hypophysectomy; D007770:L-Lactate Dehydrogenase / Q000235:genetics; D008297:Male; D018832:Molecular Chaperones; D009929:Organ Size / Q000187:drug effects; D010735:Phosphoglycerate Kinase / Q000235:genetics; D011479:Protamines / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012708:Sertoli Cells / Q000378:metabolism*; D013076:Sperm Count; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*; D013737:Testis / Q000187:drug effects / Q000502:physiology*; D013739:Testosterone / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D051152:Clusterin; D004343:Drug Implants; D006023:Glycoproteins; D018832:Molecular Chaperones; D011479:Protamines; D012333:RNA, Messenger; D013739:Testosterone; D007770:L-Lactate Dehydrogenase; D010735:Phosphoglycerate Kinase