Ex Vivo Evaluation of Buserelin Permeation Across Porcine Endometrial Tissue: A Pilot Study.
Buserelin permeated over 61% of porcine endometrial tissue in 8 hours, with early enhancement from diluted semen but no overall difference in cumulative diffusion.
Where it sits
this study against the rest of the buserelin corpusSummary and findings
This study evaluated the diffusion of buserelin across porcine endometrial tissue using an ex vivo model. The primary objective was to determine the permeation of buserelin, either alone or with extended boar semen, through sow uterine tissue. Results indicated that over 61% of buserelin permeated the tissue within 8 hours, with no significant difference between the two groups.
Abstract
Buserelin, a gonadotropin-releasing hormone (GnRH) analog, is commonly used in swine to induce ovulation and facilitate fixed-time artificial insemination (FTAI). Supplementation of diluted semen with buserelin has been developed as a less invasive approach to synchronize ovulation and potentially enhance litter size in gilts. This study evaluated the diffusion of buserelin across porcine endometrial tissue using an ex vivo Franz diffusion cell system. The primary objective was to determine whether buserelin, either alone or in combination with extended boar semen, could penetrate sow uterine tissue. Endometrial tissues were collected post-mortem from six sows confirmed to be in the follicular phase by macroscopic examination of the reproductive tract. Each uterine sample was divided into two portions and assigned to either a buserelin group or a buserelin plus diluted semen group. Boar semen used for the diluted semen group was prepared using a commercial extender, and the pH of all test samples was measured prior to analysis. Diffusion studies were performed using vertical Franz diffusion cells maintained at 37 °C, with phosphate-buffered saline (pH 7.4) serving as the receptor medium. To standardize the total drug dose applied (rather than the concentration or application volume), tissue samples were treated either with 4 µg of buserelin acetate in 1 mL of solution or with 4 µg of buserelin acetate in 1 mL of solution mixed with 1 mL of diluted semen. Receptor fluid was collected over an 8-h period for quantification of permeated and absorbed buserelin using high-performance liquid chromatography (HPLC). The overall percentage of buserelin permeation through porcine endometrial tissue was similar between the buserelin group (61.3 ± 7.8%; range 54.0-73.7%) and the buserelin plus diluted semen group (62.2 ± 4.6%; range 48.6-68.9%), with no significant difference (<i>p</i> = 0.840). During the first 0.75 h (0-45 min), the cumulative permeation did not differ between treatments (10.2 ± 2.4% vs. 11.8 ± 2.4%, <i>p</i> = 1.000). However, at 1.5 h, the permeation rate was lower in the buserelin group than in the buserelin plus diluted semen group (18.0 ± 2.4% vs. 29.2 ± 2.4%, <i>p</i> = 0.032). From this point onward, the buserelin plus diluted semen group maintained higher permeation until approximately 6 h, after which permeation values became comparable (<i>p</i> = 0.174). The steady-state fluxes (<i>J</i><sub>ss</sub>) were 0.21 and 0.28 µg/cm<sup>2</sup>·h, with corresponding apparent permeability coefficients (<i>P</i><sub>app</sub>) of 0.052 and 0.069 cm/h, respectively. In conclusion, this ex vivo pilot study showed that more than 61% of the administered buserelin permeated porcine endometrial tissue within 8 h, irrespective of semen supplementation. The addition of diluted semen enhanced permeation during the early phase but did not affect the overall cumulative diffusion.
Background
This paper addresses the permeation of buserelin, a gonadotropin-releasing hormone analog, through porcine endometrial tissue. Previous studies have indicated its use in swine for ovulation induction, but the specifics of its tissue penetration remain unclear. Understanding the diffusion characteristics of buserelin is important for optimizing its use in reproductive management in swine.
Methods
The study utilized an ex vivo Franz diffusion cell system to evaluate buserelin permeation. Endometrial tissues were collected post-mortem from six sows in the follicular phase. Each sample was treated with either 4 µg of buserelin alone or mixed with diluted semen, and diffusion was assessed over an 8-hour period.
Results
The primary endpoint showed that 61.3 ± 7.8% of buserelin permeated through the endometrial tissue in the buserelin group, while 62.2 ± 4.6% permeated in the buserelin plus diluted semen group, with no significant difference (p=0.840). At 1.5 hours, the permeation rate was significantly lower in the buserelin group compared to the combination group (p=0.032).
Interpretation
The findings suggest that while buserelin can permeate porcine endometrial tissue effectively, the addition of diluted semen enhances early permeation rates. However, the overall cumulative diffusion was similar between the two groups, indicating that the clinical relevance of this enhancement may be limited. The small sample size and ex vivo model may confound the applicability of these results to in vivo situations.
Key findings
- 61.3 ± 7.8% buserelin permeation in the buserelin group, n=6.
- 62.2 ± 4.6% buserelin permeation in the buserelin plus diluted semen group, n=6, p=0.840.
- Cumulative permeation at 0.75 h: 10.2 ± 2.4% vs. 11.8 ± 2.4%, p=1.000.
- At 1.5 h, permeation was 18.0 ± 2.4% for buserelin and 29.2 ± 2.4% for buserelin plus diluted semen, p=0.032.
- Steady-state fluxes were 0.21 µg/cm²·h for buserelin and 0.28 µg/cm²·h for buserelin plus diluted semen.
- Apparent permeability coefficients were 0.052 cm/h for buserelin and 0.069 cm/h for buserelin plus diluted semen.
Limitations
- small n=6
- ex vivo model may not replicate in vivo conditions
- short follow-up period of 8 hours