Steroidal control of gonadotrophin secretion in the orchidectomized dog

Winter, Mark L.; Pirmann, J.; Falvo, Richard E.; Schanbacher, B. D.; Miller, Joan G.

doi:10.1530/jrf.0.0640449

Cited by 14 publications

(5 citation statements)

References 13 publications

(8 reference statements)

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“…The capsules were rinsed with 70% ethanol and then with sterile saline, and were implanted just caudal to the shoulder region of anesthetized dogs. In castrated dogs, normal intact plasma concentrations of the appropriate steroid had been restored by implanting one 7-cm long capsule filled with T per 4 kg body weight [19], one 7-cm long capsule filled with DHT per 7 kg body weight [20], and one 7-cm long capsule filled with E, per 10 kg body weight [21].…”

Section: Steroid and Capsule Preparationmentioning

confidence: 99%

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Induction of benign prostatic hyperplasia in intact dogs by near‐physiological levels of 5α‐dihydrotestosterone and 17β‐estradiol

et al. 1995

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Benign prostatic hyperplasia was induced in mongrel dogs treated for 60 days with one silastic implant containing 17 beta-estradiol and four containing 5 alpha-dihydrotestosterone. The condition was characterized by (1) a marked increase of the stromal elements, particularly the stromal septa between the individual glands, (2) a slight increase in prostatic volume, and (3) a morphology that resembled spontaneous complex benign prostatic hyperplasia in the dog. Other groups of animals that remained untreated or received only 17 beta-estradiol or only 5 alpha-dihydrotestosterone did not develop this condition. Prostate volumes decreased by 14% in the estrogen-treated dogs, whereas they increased in the androgen-treated animals by 6% compared to pretreatment prostate volumes. The morphology of the epithelium of the prostates of androgen-treated animals was not different from that of controls despite the increase in prostate volume. The serum 17 beta-estradiol and 5 alpha-dihydrotestosterone concentrations were increased from 25 +/- 2 (mean +/- SEM) and 256 +/- 42 pg/mL, respectively, in control dogs to 52 +/- 37 and 562 +/- 37 pg/mL, respectively, in the dogs treated with the hormone combination. Thus, hormone concentrations were two- to three-fold higher than control values, and the ratio of estradiol-17 beta to 5 alpha-dihydrotestosterone was increased by up to 19%. These data demonstrate that treatment of dogs with low levels of estrogen and androgen may be an excellent model for the study of spontaneous complex benign prostatic hyperplasia in aging men.

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Section: Steroid and Capsule Preparationmentioning

confidence: 99%

“…For the pilot studies, blood samples were drawn from each dog and centrifuged, and the plasma was stored in three aliquots at -20°C. Plasma samples were pooled and assayed according to radioimmunoassay (RIA) methods previously published: T [19], DHT [20], and E, [21] for the pilot studies.…”

Section: Measurement Of Plasma Steroid Concentrationsmentioning

confidence: 99%

Induction of benign prostatic hyperplasia in intact dogs by near‐physiological levels of 5α‐dihydrotestosterone and 17β‐estradiol

et al. 1995

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“…During the day LH ranges from 0.2 to 11.0 ng/ml. Regulation of LH secretion involves aromatization of androgen to estrogen in the brain and effects of systemic estrogen on the pituitary (Winter et al, 1982;Aman, 1986). LH secretion is inhibited more by es tradiol than by testosterone (Winter et al, 1982).…”

Section: Male Hormone Patternsmentioning

confidence: 99%

Reproduction in the Dog and Cat

Concannon¹

1991

Reproduction in Domestic Animals

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“…This is probably mediated via the KiSS‐1/gpr‐54 system, as the Kisspeptin neurons, that have been shown to induce GnRH secretion by the GnRH neurons, express the sex steroids receptors that the GnRH neurons lack (Albers‐Wolthers et al, 2014 ; Oakley et al, 2009 ; Roseweir & Millar, 2009 ; Tsutsui et al, 2010 ). The removal of the negative feedback is followed by an increased secretion of LH and FSH (DePalatis et al, 1978 ; Reichler et al, 2004 ; Winter et al, 1982 ; Winter et al, 1983 ). In contrast to SC, plasma LH and FSH concentrations decreased after CC, which is in line with the proposed mechanism of action, namely downregulation of the GnRH receptors and desensitization of the pituitary gonadotrophs as a result of the continuously elevated plasma GnRH concentration (Jones et al, 1976 ; Junaidi et al, 2007 ; Vickery et al, 1984 ).…”

Section: Discussionmentioning

confidence: 99%

The function of the pituitary‐testicular axis in dogs prior to and following surgical or chemical castration with the GnRH‐agonist deslorelin

Spruijt

Kooistra

Oei

et al. 2022

Reprod Domestic Animals

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Chemical castration, that is the reduction of circulating testosterone concentrations to castrate levels by administration of a GnRH-agonist implant, is a popular alternative to surgical castration in male dogs. Detailed information concerning the pituitarytesticular axis following administration of a GnRH-agonist implant is still scarce.Therefore, GnRH-stimulation tests were performed in male dogs, prior to and after surgical and chemical castration. This approach also allowed us to determine plasma concentrations of testosterone and oestradiol in intact male dogs for future reference and to directly compare the effects of surgical and chemical castration on the pituitarytesticular axis. In intact male dogs (n = 42) of different breeds GnRH administration induced increased plasma LH, FSH, oestradiol and testosterone concentrations. After surgical castration basal and GnRH-induced plasma FSH and LH concentrations increased pronouncedly. Additionally, basal and GnRH-induced plasma oestradiol and testosterone concentrations decreased after surgical castration. After chemical castration, with a slow-release implant containing the GnRH-agonist deslorelin, plasma LH and FSH concentrations were lower than prior to castration and lower compared with the same interval after surgical castration. Consequently, plasma oestradiol and testosterone concentrations were lowered to values similar to those after surgical castration. GnRH administration to the chemically castrated male dogs induced a significant increase in the plasma concentrations of LH, but not of FSH. In conclusion, after administration of the deslorelin implant, the plasma concentrations of oestradiol and testosterone did not differ significantly from the surgically castrated animals.After GnRH-stimulation, none of the dogs went to pre-treatment testosterone levels.However, at the moment of assessment at 4,4 months (mean 133 days ± SEM 4 days), the pituitary gonadotrophs were responsive to GnRH in implanted dogs. The increase of LH, but not of FSH, following GnRH administration indicates a differential regulation of the release of these gonadotrophins, which needs to be considered when GnRH-stimulation tests are performed in implanted dogs.

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Steroidal control of gonadotrophin secretion in the orchidectomized dog

Cited by 14 publications

References 13 publications

Induction of benign prostatic hyperplasia in intact dogs by near‐physiological levels of 5α‐dihydrotestosterone and 17β‐estradiol

Induction of benign prostatic hyperplasia in intact dogs by near‐physiological levels of 5α‐dihydrotestosterone and 17β‐estradiol

Reproduction in the Dog and Cat

The function of the pituitary‐testicular axis in dogs prior to and following surgical or chemical castration with the GnRH‐agonist deslorelin

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