Effect of GnRH conjugated to pokeweed antiviral protein on reproductive function in adult male dogs

K. Sabeur, B. A. Ball, T. M. Nett, H. H. Ball, I. K.M. Liu

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

This study evaluated the effect of a GnRH analogue conjugated to the cytotoxin, pokeweed antiviral protein (PAP), on reproductive function in adult, male dogs. Four dogs received 0.0042 mg GnRH-PAP kg-1 hourly for 36 h, and four other dogs received 0.1 mg GnRH-PAP kg-1 as one bolus injection daily for three consecutive days. One dog received a single bolus (0.1 mg kg-1). Three adult male dogs received GnRH without the PAP conjugate, as controls. Twenty-five weeks after the initial treatment, all treated dogs received 0.1 mg GnRH-PAP kg-1 as a single administration, whereas dogs in the control group received 0.0045 mg kg-1 of the GnRH analogue. Serum concentrations of testosterone and LH were determined by radioimmunoassay, and testis size was measured for 9 months after treatment. Stimulation tests (5 μg GnRH kg-1) were used to evaluate LH release (-15, 0, 30, 60, 90, 120 min), which was assessed by measuring area under the curve. Serum testosterone concentrations were significantly lower (P < 0.05) after treatment in the bolus and hourly groups than in the control group. Testosterone concentrations fell to less than 50 pg ml-1 in three of four dogs in the bolus group and one of four dogs in the hourly group by week 8-9 after treatment. Basal LH was lower (P < 0.05) in the bolus and hourly groups than in the control group between weeks 0 and 33 after treatment. Treatment with GnRH-PAP reduced (P < 0.05) LH release after GnRH stimulation in the bolus and hourly groups compared with the control group. Testis volume was lower (P < 0.05) in all treated versus control dogs. In conclusion, administration of the conjugate GnRH-PAP at a 25 week interval resulted in a major disruption of reproductive parameters in male dogs; this effect was maintained for 11-12 weeks after a second injection of GnRH-PAP.

Original languageEnglish
Pages (from-to)801-806
Number of pages6
JournalReproduction
Volume125
Issue number6
DOIs
StatePublished - Jun 1 2003

ASJC Scopus subject areas

  • Reproductive Medicine
  • Embryology
  • Endocrinology
  • Obstetrics and Gynecology
  • Cell Biology

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