Charakterisierung der induzierbaren Kontraktionen des Ductus deferens - Ihre Bedeutung für den Weitertransport der Spermatozoen
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Beschreibung
The spermatozoa stored in the distal epididymal tail are transported into the urethra during ejaculation by mainly adrenergically controlled contractions. However, the intricate process of emission is not yet fully understood. Earlier studies by our research group have shown that oxytocin (OT) in the distal epididymal tail (segment 19), equivalent to the transmitter noradrenaline (NA), was able to trigger strong contractions that led to the visible ejection of spermatozoa.
Following the sperm passage towards the urethra, the contractility of the vas deferens (ductus deferens) and its responsiveness to OT in comparison to NA should now be clarified in this work. Previous organ bath studies on the vas deferens led in part to contradictory results, which could be due, among other things, to the fact that only some parts of the vas deferens were examined.
In this study, the entire length of the vas deferens of the rat (from the epididymis to the prostate), consisting of the 1st loop, pars epididymica, pars libera and pars prostatica, was divided into smaller sections of approx. 3 mm each and investigated for contractile effects. For the first time, live imaging with pixel-precise analysis was used to assess the contractility of the tissue without pretensioning the tissue and to detect multidirectional effects if present.
The substances NA and OT had regionally different contractile effects in the vas deferens regions. With NA, the contractile effect decreased from the pars epididymica distally to the last part of the pars prostatica (pars epididymica > pars libera > pars prostatica). For both NA and OT, the strongest effect was observed in the pars epididymica, with NA having a stronger effect in all areas. Only in the pars prostatica both substances were similarly weak. While the contractions triggered by NA were almost equally strong in the pars epididymica and in the distal epididymal tail, they were significantly weaker with OT in the pars epididymica than in the distal epididymal tail. The examinations also showed that the vas deferens contracted mainly in the longitudinal direction and that the effect on the lumen was barely visible. Surprisingly, a single spontaneously contracting region was found at the transition from pars epididymica to pars libera.
Our results indicate that, in addition to the distal epididymal tail (segment 19), the strong contractions in the area of the pars epididymica are particularly important for the process of sperm expulsion. It is therefore conceivable that influencing both the adrenergic and OT signalling pathways could be used for the treatment of ejaculation disorders. However, this requires further investigation.
Autor*in
Helena Alexandra Baum
Themen in »Charakterisierung der induzierbaren Kontraktionen des Ductus deferens - Ihre Bedeutung für den Weitertransport der Spermatozoen«
Samenleiter (Ductus deferens) Kontraktilität, Kontraktionsverhalten Oxytocin (OT) vs. Noradrenalin (NA) Pars epididymica, Pars libera, Pars prostatica Live-Imaging, Gewebeanalyse Ejakulationsmechanismus, Spermienaustreibung Nebenhodenschweif Adrenerg