biostudies-literatureUnknown16(2)Goericke-Pesch SFollowing the downregulation of testicular endocrine and germinative function by slow-release gonadotropin-releasing hormone (GnRH)-agonist implants, testicular functions are quickly restored after implant removal. As an intact blood-testis barrier (BTB) is crucial for normal spermatogenesis and its integrity is FSH- and androgen-dependent, alterations in the BTB gene and protein expressions during downregulation and subsequent restart seem inevitable. We investigated <i>occludin</i> (<i>OCLN</i>), <i>claudin</i> (<i>CLDN</i>) <i>3</i>, <i>5</i>, <i>11,</i> and <i>connexin</i> (<i>CX</i>) <i>43</i> mRNA-, and CLDN11 and CX43 protein expressions during GnRH implant-induced downregulation (W0) and restart of spermatogenesis after implant removal (week, W, 3-12). Untreated juvenile (JG) and aAnimals : an open access journal from MDPI254https://www.ebi.ac.uk/biostudies/studies/S-EPMC12837560biostudies-literatureTesticular Gap (<i>CX43</i>) and Tight Junction (<i>OCLN</i>, <i>CLDN3</i>, <i>5</i> and <i>11</i>) Components in the Dog Are Affected by GnRH-Mediated Downregulation.PMC12837560Frimodt Ronnow AKorber HWallrabenstein SLangeheine MGoericke-Pesch SPackeiser EMFietz DRohrs LBrehm RWehrend AHoffmann BfalseTesticular Gap (<i>CX43</i>) and Tight Junction (<i>OCLN</i>, <i>CLDN3</i>, <i>5</i> and <i>11</i>) Components in the Dog Are Affected by GnRH-Mediated Downregulation.Following the downregulation of testicular endocrine and germinative function by slow-release gonadotropin-releasing hormone (GnRH)-agonist implants, testicular functions are quickly restored after implant removal. As an intact blood-testis barrier (BTB) is crucial for normal spermatogenesis and its integrity is FSH- and androgen-dependent, alterations in the BTB gene and protein expressions during downregulation and subsequent restart seem inevitable. We investigated <i>occludin</i> (<i>OCLN</i>), <i>claudin</i> (<i>CLDN</i>) <i>3</i>, <i>5</i>, <i>11,</i> and <i>connexin</i> (<i>CX</i>) <i>43</i> mRNA-, and CLDN11 and CX43 protein expressions during GnRH implant-induced downregulation (W0) and restart of spermatogenesis after implant removal (week, W, 3-12). Untreated juvenile (JG) and a2026-01-01T00:00:00Z2026 Jan2026-06-12T03:16:56.931Z2026-06-12T03:11:26.354ZS-EPMC128375604159444310.3390/ani16020254