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BMC veterinary research2025; 21(1); 572; doi: 10.1186/s12917-025-05025-y

Alterations in the penile artery blood flow hemodynamics and hormonal profile in jacks (Equus asinus) after a single administration of human chorionic gonadotropin (hCG).

Abstract: The penis of the donkey is a musclocavernous type as the erection of the penis is dependent on the blood flow within the cavernous tissue inside the penis,This current study aimed for the first time to determine the effect of human chorionic gonadotropin (hCG) injection on penile artery blood flow hemodynamics and erection process after carefully studying the anatomical architecture of the penile blood supply. This study was conducted on 23 donkeys as 3 Male cadavers were used for anatomical findings and the other 20 live jacks were subdivided into two equal groups (Group I [treated jacks;  = 10] and Group II [control males;  = 10]). The arterial supply of the penis of the horse is oriented by external pudendal, internal pudendal and obturator arteries. The penile artery Doppler indices were declined ( < 0.05) in the hCG group after a single injection of hCG by 2,4 and reached the lowest level at 6 h. The penile blood flow volume reached the highest level 6 h after injection. The levels of both nitric oxide (NO), estradiol (E2), and follicle-stimulating hormone (FSH) were elevated, reaching the peak point after 6 h. of injection for E2 and NO and 4 h for FSH. There was a positive correlation between penile blood flow and both NO and E2 (NO with  = 0.66;  = 0.01, and E2 with r = 0.69;  = 0.01). In conclusion, the single administration of hCG improves the penile artery vascularity and hormonal levels at 6 h. post-injection, which positively affects penile function and the erection process in jacks ).
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Publication Date: 2025-10-03 PubMed ID: 41044793PubMed Central: PMC12492599DOI: 10.1186/s12917-025-05025-yGoogle Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Alterations in penile artery blood flow and hormonal profile were investigated in donkeys (jacks) after a single injection of human chorionic gonadotropin (hCG), revealing improved penile vascularity and hormonal changes that enhance penile function and erection.

Study Purpose and Background

  • The research aimed to explore, for the first time, how a single dose of hCG affects penile artery blood flow and erection in donkeys (Equus asinus).
  • The penis in donkeys is of the musclocavernous type, meaning erection mainly depends on increased blood flow within cavernous tissue.
  • Understanding the anatomical blood supply was key to assessing hemodynamic changes induced by hCG.

Subjects and Methods

  • Total of 23 donkeys studied: 3 male cadavers for anatomical analysis and 20 live jacks for physiological experiments.
  • The 20 live jacks were divided into two groups:
    • Group I: 10 treated jacks receiving single hCG injection.
    • Group II: 10 control jacks receiving no treatment.
  • Doppler ultrasound was used to measure penile artery blood flow parameters and hemodynamic indices.
  • Hormonal assays were performed to measure levels of nitric oxide (NO), estradiol (E2), and follicle-stimulating hormone (FSH) at various times after injection.
  • Anatomical findings showed penile arterial supply comes from external pudendal, internal pudendal, and obturator arteries, aligning with equine vascular anatomy.

Key Findings on Hemodynamics

  • Doppler indices of the penile arteries (parameters such as resistance index and pulsatility index) significantly decreased after hCG injection, indicating vasodilation.
  • The decline was noted at 2 and 4 hours post-injection and reached its lowest (maximum vasodilation) at 6 hours.
  • Penile blood flow volume increased substantially, peaking at 6 hours after hCG administration.
  • The increased blood flow suggests improved vascularity and enhanced conditions for erection.

Hormonal Changes Post-hCG Injection

  • Plasma levels of nitric oxide (NO), estradiol (E2), and follicle-stimulating hormone (FSH) rose significantly after hCG administration.
  • E2 and NO peaked at 6 hours post-injection, while FSH peaked slightly earlier at 4 hours.
  • There was a strong positive correlation between penile blood flow and levels of NO (correlation coefficient r = 0.66) and E2 (r = 0.69), both statistically significant (p = 0.01).
  • These correlations suggest that hormonal changes directly influence penile hemodynamics.

Conclusions and Implications

  • A single dose of hCG significantly enhances penile artery vascularity and elevates important hormones that facilitate erection in donkeys.
  • The peak improvements in vascular and hormonal responses occur approximately 6 hours post-injection.
  • This finding suggests potential clinical or reproductive applications for hCG in managing penile function or erectile performance in jacks.
  • Overall, hCG acts as a pharmacological agent improving the physiological factors that regulate penile erection by modulating blood flow and hormone levels.

Significance of the Study

  • This is the first study to link hCG administration with direct effects on penile hemodynamics and hormonal profiles in donkeys.
  • The research contributes to veterinary reproductive physiology and could aid in treatment protocols aimed at improving male reproductive performance in equines.

Cite This Article

APA
Karmoty AFE, Fathi M, Emam IA, Tolba A, Abdelnaby EA, Alhaider AK, Abouelela YS. (2025). Alterations in the penile artery blood flow hemodynamics and hormonal profile in jacks (Equus asinus) after a single administration of human chorionic gonadotropin (hCG). BMC Vet Res, 21(1), 572. https://doi.org/10.1186/s12917-025-05025-y

Publication

BMC veterinary research
ISSN: 1746-6148
NlmUniqueID: 101249759
Country: England
Language: English
Volume: 21
Issue: 1
Pages: 572
PII: 572

Researcher Affiliations

Karmoty, Amr F El
  • Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Cairo University, Giza Squarem, 12211, Egypt.
Fathi, Mohamed
  • Department of Theriogenology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
Emam, Ibrahim A
  • Department of Surgery, Anesthesiology and Radiology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt.
Tolba, Ayman
  • Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Cairo University, Giza Squarem, 12211, Egypt.
Abdelnaby, Elshymaa A
  • Department of Theriogenology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
  • Department of Clinical Sciences, College of Veterinary Medicine, King Faisal University, P.O. Box 400, 31982, Al‑Ahsa, Saudi Arabia.
Alhaider, Abdulrahman K
  • Department of Clinical Sciences, College of Veterinary Medicine, King Faisal University, P.O. Box 400, 31982, Al‑Ahsa, Saudi Arabia.
Abouelela, Yara S
  • Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Cairo University, Giza Squarem, 12211, Egypt. yarasayed89@cu.edu.eg.

Conflict of Interest Statement

Declarations. Ethics approval and consent to participate: Our study was operated, including animal manipulation and sampling according to the approval of the Veterinary Animal Care and Use Committee of the Faculty of Veterinary Medicine, Cairo University in strict compliance with the ARRIVE Guidelines 2.0 for reporting animal research, the National Institute of Health Guide for Care and Use of Laboratory Animals (NIH Publication no. 85–23, revised 2011) and the UK Animals (Scientific Procedures) Act 1986 with Approval number Vet CU 08072023724. Consent for publication: All authors read and approved the manuscript. Competing interests: The authors declare no competing interests.

References

This article includes 47 references
  1. Hong S, Choi W, Lee KW, Lee YT, Kwon T. Penile length and circumference: are they related to nose size?. Transl Androl Urol 2023;12(5):708–14.
    doi: 10.21037/tau-22-869pmc: PMC10251097pubmed: 37305632google scholar: lookup
  2. Love CC, McDonnell SM, Kenney RM. Manually assisted ejaculation in a stallion with erectile dysfunction subsequent to paraphimosis. J Am Vet Med Assoc 1992;200(9):1357–9.
    doi: 10.2460/javma.1992.200.09.1357pubmed: 1601723google scholar: lookup
  3. Azadzoi KM, Vlachiotis J, Pontari M, Siroky MB. Hemodynamics of penile erection. III. Measurement of deep intracavernosal and subtunical blood flow and oxygen tension. J Urol 1995;153:521–6.
    doi: 10.1097/00005392-199502000-00075pubmed: 7815637google scholar: lookup
  4. Andersson KE, Wagner G. Physiology of penile erection. Physiol Rev 1995;75:191–236.
    doi: 10.1152/physrev.1995.75.1.191pubmed: 7831397google scholar: lookup
  5. Fernandes MV, de Souza LRM, Cartafina LP. Ultrasound evaluation of the penis. Radiol Bras 2018;51(4):257–61.
    doi: 10.1590/0100-3984.2016.0152pmc: PMC6124582pubmed: 30202130google scholar: lookup
  6. Altinbas NK, Hamidi N. Penile doppler ultrasonography and elastography evaluation in patients with erectile dysfunction. Pol J Radiol 2018;83:491–9.
    doi: 10.5114/pjr.2018.80301pmc: PMC6334185pubmed: 30655929google scholar: lookup
  7. Schurich M, Aigner F, Frauscher F, Pallwein L. The role of ultrasound in assessment of male fertility. Eur J Obstet Gynecol Reprod Biol 2009;144:192–8.
    doi: 10.1016/j.ejogrb.2009.02.034pubmed: 19303691google scholar: lookup
  8. Pozor MA, McDonnell SM. Color doppler ultrasound evaluation of testicular blood flow in stallions. Theriogenology 2004;61:799–810.
    doi: 10.1016/s0093-691x(03)00227-9pubmed: 14757466google scholar: lookup
  9. Carrillo JD, Soler M, Lucas X, Agut A. Colour and pulsed Doppler ultrasonographic study of the canine testis. Reprod Domest Anim 2012;47:655–9.
    doi: 10.1111/j.1439-0531.2011.01937.xpubmed: 22117645google scholar: lookup
  10. Zelli R, Troisi A, Ngonput AE, Cardinali L, Polisca A. Evaluation of testicular artery blood flow by Doppler ultrasonography as a predictor of spermatogenesis in the dog. Res Vet Sci 2013;95:632–7.
    doi: 10.1016/j.rvsc.2013.04.023pubmed: 23714041google scholar: lookup
  11. Kutzler M, Tyson R, Grimes M, Timm K. Determination of testicular blood flow in camelids using vascular casting and color pulsed-wave doppler ultrasonography. Vet Med Int 2011;1:1–7.
    doi: 10.4061/2011/638602pmc: PMC3175731pubmed: 21941690google scholar: lookup
  12. Malgorzata P. Ultrasonography of the penis. Atlas of equine ultrasonography 2014, 267–27.
    doi: 10.1002/9781118798119.ch12google scholar: lookup
  13. Frandson RD, Lee Wilke W, Anna Dee Fails. Anatomy and physiology of farm animals. 2009. 7 edition (Pp412).
  14. Benjamin DS. Placing erection in context: the reflexogenic-psychogenic dichotomy reconsidered. Neurosci Biobehav Rev 1995;19(2):211–24.
    doi: 10.1016/0149-7634(94)00063-7pubmed: 7630577google scholar: lookup
  15. Blanchard TL, Jorgensen JB, Jorgensen JB, Forrest DW, Evans JW, Varner DD. Relationship of bioactive luteinizing hormone to hormonal and semen parameters in stallions. Biol Reprod 1995;52(monograph_series1):623–9.
    doi: 10.1093/biolreprod/52.monograph_series1.623google scholar: lookup
  16. Ball BA. Diagnostic methods for evaluation of stallion subfertility: a review.. J Equine Vet Sci 2008;28(11):650–65.
    doi: 10.1016/j.jevs.2008.10.003google scholar: lookup
  17. Abdelnaby EA, Abouelela S, Yasin NA E. Evaluation of penile blood flow in dogs with tvt before and after chemotherapeutic treatment with special reference to its angioarchitecture.. Advances in Animal and Veterinary Sciences 2021;9(8):1159–2116.
    doi: 10.17582/journal.aavs/2021/9.8.1159.1168google scholar: lookup
  18. El-Bably SH, Abouelela YS. Anatomical and radiographical studies on heart of red fox (vulpes vulpes) with special references to its coronary arteries.. Adv Anim Vet Sci 2021;9:754–760.
    doi: 10.17582/journal.aavs/2021/9.8.1159.1168google scholar: lookup
  19. Bollwein H, Schulze JJ, Miyamoto A, Sieme H. Testicular blood flow and plasma concentrations of testosterone and total estrogen in the stallion after the administration of human chorionic gonadotropin.. J Reprod Dev 2008;54(5):335–9.
    doi: 10.1262/jrd.20014pubmed: 18667792google scholar: lookup
  20. Abdelnaby EA. Testicular haemodynamics, plasma testosterone and oestradiol concentrations, and serum nitric oxide levels in the Egyptian buffalo bull after a single administration of human chorionic gonadotropin.. Reprod Domest Anim 2022;57:754–60.
    doi: 10.1111/rda.14117pubmed: 35352415google scholar: lookup
  21. Abdelnaby EA, Emam IA, Fadl AM. Assessment of the accuracy of testicular dysfunction detection in jacks () with the aid of colour- spectral Doppler in relation to plasma testosterone and serum nitric oxide levels.. Reprod Domest Anim 2021;56(5):764–74.
    doi: 10.1111/rda.13916pubmed: 33595865google scholar: lookup
  22. Farghali HA, AbdElKader NA, Fathi M, Emam IA, AbuBakr HO, Alijuaydi SH. The efficiency of intrauterine infusion of platelet- rich plasma in the treatment of acute endometritis as assessed by endoscopic, Doppler, oxidative, immunohistochemical, and gene expression alterations in jennies.. Theriogenology 2022;181:147–60.
    doi: 10.1016/j.theriogenology.2022.01.023pubmed: 35101679google scholar: lookup
  23. Ma M, Botao Yu, Feng Qin, Jiuhong Yu. Current approaches to the diagnosis of vascular erectile dysfunction.. Transl Andrology Urology 2020;9(2).
    pmc: PMC7215019pubmed: 32420178
  24. Ortiz-Rodriguez JM, Anel-Lopez L, Martín-Muñoz P, Álvarez M, Gaitskell-Phillips G, Anel L. Pulse doppler ultrasound as a tool for the diagnosis of chronic testicular dysfunction in stallions.. PLoS ONE 2017;12(5):e0175878.
    doi: 10.1371/journal.pone.0175878pmc: PMC5448730pubmed: 28558006google scholar: lookup
  25. Gracia-Calvo LA, Duque J, Balao da Silva C, Ezquerra J, OrtegaFerrusola C. Testicular perfusion after standing laparoscopic peritoneal flap hernioplasty in stallions.. Theriogenology 2015;84(5):797–804.
    pubmed: 26116054doi: 10.1016/j.theriogenology.2015.05.014google scholar: lookup
  26. Ribeiro DL, dos Santos LS, de França IG, Pereira HG, Lima J, Miranda BDB. The use of Doppler ultrasound as a potential fertility predictor in male goats.. Turk J Vet Anim Sci 2020;44:1115–24.
    doi: 10.3906/vet-2003-135google scholar: lookup
  27. Budras KD, Sack WO, Röck S. Textbook anatomy of the horse.. 2009; 5 edition.
  28. Parlevliet JM, Bevers MM, Broek J, Colenbrander B. Effect of GNRH and HCG administration on plasma LH and testosterone concentrations in normal stallions, aged stallions and stallions with lack of libido.. Vet Quart 2001 23(2).
    pubmed: 11361105
  29. Tsunoda N, Weng Q, Nagata S, Taniyama H, Watanabe G, Taya K. Effect of a single injection of human chorionic gonadotropin (hCG) on testicular hormones and gonadotropins in the Thoroughbred stallion.. J Equine Sci 2007.
    doi: 10.1294/jes.18.107google scholar: lookup
  30. Pakarinen P, Vihko KK, Voutilainen R, Huhtaniemi I. Differential response of luteinizing hormone receptor and steroidogenic enzyme gene expression to human chorionic gonadotropin stimulation in the neonatal and adult rat testis.. Endocrinology 1990;127:2469–74.
    doi: 10.1210/endo-127-5-2469pubmed: 2226328google scholar: lookup
  31. Akhtar RW, Shah SAH, Qureshi IZ. Effect of kisspeptin-10, LH and hCG on serum testosterone concentrations in stallions, donkeys and mules.. Theriogenology 2017; 15:102:75–79.
    pubmed: 28753433doi: 10.1016/j.theriogenology.2017.07.027google scholar: lookup
  32. Johannes CB, Araujo AB, Feldman HA, Derby CA, Kleinman KP, McKinlay JB. Incidence of erectile dysfunction in men 40 to 69 years old: longitudinal results from the Massachusetts male aging study.. J Urol 2000;163:460–3.
    doi: 10.1016/S0022-5347(05)67900-1pubmed: 10647654google scholar: lookup
  33. Saenz de Tejada I, Cadavid N, Heaton J, Hedlund H, Nehra A, Prickard RS, Simonsen U, Steers WD. Anatomy, physiology and pathophysiology of erectile function. Erectile Dysfunction 2000, pp 3–105.
  34. Moreland RB, Hsieh G, Nakane M, Brioni JD. The biochemical and neurologic basis for the treatment of male erectile dysfunction.. J Pharmacol Exp Ther 2001;296:225–34.
    doi: 10.1016/S0022-3565(24)38739-7pubmed: 11160602google scholar: lookup
  35. Sangiorgi G, Cereda A, Benedetto D, Bonanni M, Chiricolo G, Cota L. Anatomy, pathophysiology, molecular mechanisms, and clinical management of erectile dysfunction in patients affected by coronary artery disease: a review.. Biomedicines 2021;9(4):432.
    doi: 10.3390/biomedicines9040432pmc: PMC8074129pubmed: 33923709google scholar: lookup
  36. Akorede BA, Hassan SA, Akhigbe RE. Penile erection and cardiovascular function: effects and pathophysiology.. Aging Male 2024.
    doi: 10.1080/13685538.2024.2336627pubmed: 38567396google scholar: lookup
  37. Gracia-Calvo LA, Duque J, Balao da Silva C, Ezquerra J, Ortega-Ferrusola C. Testicular perfusion after standing laparoscopic peritoneal flap hernioplasty in stallions.. Theriogenology 2015; 84(5):797–804.
    pubmed: 26116054doi: 10.1016/j.theriogenology.2015.05.014google scholar: lookup
  38. Salama A, Abdelnaby EA, Emam IA, Fathi M. Single melatonin injection enhances the testicular artery hemodynamic, reproductive hormones, and semen parameters in German shepherd dogs.. BMC Vet Res 2022;18(1):403.
    doi: 10.1186/s12917-022-03487-ypmc: PMC9664593pubmed: 36376876google scholar: lookup
  39. Abdelnaby EA, Alhaider AK, Ghoneim IM, Salem NY, Ramadan ES, Farghali HA. Effect of pyometra on vascularity alterations, oxidative stress, histopathology and inflammatory molecules in feline.. Reprod Biol 2024;24(1):100855.
    doi: 10.1016/j.repbio.2024.100855pubmed: 38262266google scholar: lookup
  40. Abdelnaby EA, Alhaider AK, El-Maaty AMA, Ragab RSA, Seida AA, El-Badry DA. Ovarian and uterine arteries blood flow velocities waveform, hormones and nitric oxide in relation to ovulation in cows superstimulated with equine chorionic gonadotropin and luteolysis induction 10 and 17 days after ovulation.. BMC Vet Res 2023;19(1):205.
    doi: 10.1186/s12917-023-03692-3pmc: PMC10571355pubmed: 37833782google scholar: lookup
  41. Madbouly H, El-Shahat KH, Fathi M, Abdelnaby EA. Hemodynamic changes in late advanced pregnant Zaraibi goats during the peripartum period.. BMC Vet Res 2023;19(1):194.
    doi: 10.1186/s12917-023-03745-7pmc: PMC10559465pubmed: 37803319google scholar: lookup
  42. Abouelela YS, Shaker NA, El-Shahat KH, Bashir DW, El-Sherbiny HR, Abdelnaby EA. Anatomical, histological, and histochemical alterations in portio vaginalis uteri with an evaluation of the vaginal artery vascularity during the luteal and early pregnant stages in domestic buffaloes ().. BMC Vet Res 2023;19(1):260.
    doi: 10.1186/s12917-023-03816-9pmc: PMC10698982pubmed: 38057858google scholar: lookup
  43. El-Sherbiny HR, Hashem NM, Abdelnaby EA. Coat color affects the resilience against heat stress impacts on testicular hemodynamics, reproductive hormones, and semen quality in Baladi goats.. BMC Vet Res 2023;19:107.
    doi: 10.1186/s12917-023-03653-wpmc: PMC10401866pubmed: 37537599google scholar: lookup
  44. Abdelnaby EA, Emam IA. L-citrulline single intravenous administration promotes testicular blood flow, plasma testosterone, estradiol, circulating citrulline and serum nitric oxide levels in male camels under heat stress at the end of non-breeding season.. Reprod Domest Anim 2025;60(5):e70079.
    doi: 10.1111/rda.70079pubmed: 40415556google scholar: lookup
  45. Abdelnaby EA, Alhaider AK, El-Maaty AMA, Ragab RSA, Seida AA, El-Badry DA. Ovarian and uterine arteries blood flow velocities waveform, hormones and nitric oxide in relation to ovulation in cows superstimulated with equine chorionic gonadotropin and luteolysis induction 10 and 17 days after ovulation.. BMC Vet Res 2023;19:205.
    doi: 10.1186/s12917-023-03692-3pmc: PMC10571355pubmed: 37833782google scholar: lookup
  46. Abdelnaby EA. Higher doses of melatonin affect ovarian and middle uterine arteries vascular blood flow and induce oestrus earlier in acyclic ewes.. Reprod Domest Anim 2020;55(7):763–9.
    doi: 10.1111/rda.13678pubmed: 32219898google scholar: lookup
  47. El Zawam A, Tibary A, Patino C. Basal levels and hCG responses of serum testosterone and estrogen in male alpacas.. Front Vet Sci 2020;7:595856.
    doi: 10.3389/fvets.2020.595856pmc: PMC7688520pubmed: 33263018google scholar: lookup

Citations

This article has been cited 1 times.
  1. Abdelnaby EA. The impacts of L-citrulline and sildenafil on penile and testicular vascular perfusion pattern, advanced testicular analysis, steroids, and semen picture in normospermic dogs.. Vet Res Commun 2025 Nov 19;50(1):45.
    doi: 10.1007/s11259-025-10965-9pubmed: 41258599google scholar: lookup
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