Effect of hypoprolactinaemia and hyperprolactinaemia on LH secretion, endocrine function of testes and structure of seminiferous tubules in boars

Jedlinska, Maria; Rozewiecka, L; Ziȩcik, Adam J.

doi:10.1530/jrf.0.1030265

Cited by 17 publications

(11 citation statements)

References 4 publications

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“…The intra-and interindividual variations observed in dogs from our colony have been reported before [38,43]. In-line with observations in boars, in which bromocryptine-induced hypoprolactinemia did not alter LH secretion patterns [30], the cabergoline-induced prolactin suppression in our dogs had no effect on the secretion patterns of LH. In the bitch it has been demonstrated that shortening of the interoestrous interval by the dopamine agonist bromocryptine is due to a direct stimulating effect of dopamine on GnRH secretion and a subsequent gonadotrophin release [44].…”

Section: Discussionsupporting

confidence: 92%

“…In boars, experimentally induced hyperprolactinemia has been shown to decrease basal LH concentrations without affecting LH pulsatility. The LH decrease was accompanied by an increase in testosterone concentrations [30]. Reduction of serum prolactin concentrations by bromocryptine did, however, not initiate a re-increase in LH concentrations.…”

Section: Introductionmentioning

confidence: 77%

“…Abnormally high prolactin concentrations have been found to inhibit gonadotrophin secretion in rats [45,46] and boars [30]. The mechanism of gonadotrophin suppression seems to be located in the hypothalamus, where the tonic GnRH activity is reduced by increased prolactin concentrations leading to an inhibition of the pulsatility of LH secretion [47].…”

Section: Discussionmentioning

confidence: 99%

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Effects of the dopamine agonist cabergoline on the pulsatile and TRH-induced secretion of prolactin, LH, and testosterone in male beagle dogs

Koch

Hoppen²,

Dieleman

et al. 2006

Theriogenology

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In the present study, the pulsatile serum profiles of prolactin, LH and testosterone were investigated in eight clinically healthy fertile male beagles of one to six years of age. Serum hormone concentrations were determined in blood samples collected at 15 min intervals over a period of 6 h before (control) and six days before the end of a four weeks treatment with the dopamine agonist cabergoline (5 mg kg À1 bodyweight/day). In addition, the effect of cabergoline administration was investigated on thyrotropin-releasing hormone (TRH)-induced changes in the serum concentrations of these hormones.In all eight dogs, the serum prolactin concentrations (mean 3.0 AE 0.3 ng ml À1 ) were on a relatively constant level not showing any pulsatility, while the secretion patterns of LH and testosterone were characterised by several hormone pulses. Cabergoline administration caused a minor but significant reduction of the mean prolactin concentration (2.9 AE 0.2 ng ml À1 , p < 0.05) and did not affect the secretion of LH (mean 4.6 AE 1.3 ng ml À1 versus 4.4 AE 1.7 ng ml À1 ) or testosterone (2.5 AE 0.9 ng ml À1 versus 2.4 AE 1.2 ng ml À1 ). Under control conditions, a significant prolactin release was induced by intravenous TRH administration (before TRH: 3.8 AE 0.9 ng ml À1 ,

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

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Effects of the dopamine agonist cabergoline on the pulsatile and TRH-induced secretion of prolactin, LH, and testosterone in male beagle dogs

Koch

Hoppen²,

Dieleman

et al. 2006

Theriogenology

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“…2006). The same effect was observed in boars after treatment with CAB or bromocryptine (Jedlinska et al. 1995).…”

Section: Discussionsupporting

confidence: 65%

“…In both men and rats, excessive release of PRL leads to suppression of sexual behaviour and gonadotropin secretion. Similar to the situation in the rat, both hypo‐ and hyperprolactinaemia are detrimental to testicular function in the domestic boar (Jedlinska et al. 1995; Bartke et al.…”

Section: Introductionmentioning

confidence: 84%

Effects of Short‐term Hyper‐ and Hypoprolactinaemia on Hormones of the Pituitary, Gonad and ‐Thyroid Axis and on Semen Quality in Male Beagles

Koivisto

Eschricht²,

Urhausen³

et al. 2009

Reprod Domestic Animals

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Effects of a short-term hyper- and hypoprolactinaemia on serum concentrations of LH, testosterone and semen quality in six male Beagles were investigated. Blood samples were collected at 3-day intervals for 12 weeks. The time span was divided into five 3-week periods: pre-treatment, metoclopramide (MCP) treatment (0.2 mg/kg orally three times daily), cabergoline (CAB) treatment (5 microg/kg orally once daily), post-treatment 1 and post-treatment 2. In the latter, only semen characteristics were evaluated. Semen parameters were analyzed once per week during the whole 15-week investigation time. At the end of each period, the effects of a single intravenous injection of thyrotropin-releasing hormone (TRH; 10 microg/kg) on the secretion of prolactin (PRL), LH, testosterone, thyroid-stimulating hormone and thyroxine (T4) were investigated. Pre-treatment serum PRL concentration increased under MCP (p < 0.05), followed by a decrease under CAB administration (p < 0.05). Luteinizing hormone and testosterone concentrations were not affected. Except for straight-line sperm velocity, semen quality did not differ between collection periods. A single iv TRH injection induced a significant PRL increase at 20 min in all experimental periods except during CAB treatment. Luteinizing hormone and testosterone did not show clear TRH-related changes. Basic T4 levels were significantly reduced after CAB treatment (p < 0.05). The results of the present study demonstrate that MCP-induced short-term hyperprolactinaemia in male beagles does not seriously affect the hypothalamo-pituitary axis and semen quality.

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Morphological and Morphometric Changes of Pituitary Lactotrophs of Viscacha (Lagostomus maximus maximus) in Relation to Reproductive Cycle, Age, and Sex

Filippa

Mohamed

2009

The Anatomical Record

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Lactotrophs in pituitary pars distalis (PD) of viscacha were studied by immunohistochemistry and morphometric analysis in the following groups: 1) adult males throughout the reproductive cycle (reproductive, gonadal regression, and recovery periods), 2) melatonin-treated adults, 3) castrated adults, 4) prepubertal, 5) non-pregnant females, and 6) pregnant females (early, mid, and late pregnancy). Immunopositive percentage area (%IA), cell percentage in PD (% PDC), number of cells per reference area (no.cell/ RA), major cellular and nuclear diameters were analyzed. Lactotrophs were mainly localized in the ventro-medial region and the caudal extreme of PD. In the male viscachas, they were isolated in small and big groups, close to blood vessels and near follicles. These cells were pleomorphic and with a heterogeneous cytoplasmic immunolabeling pattern. In the adult males of the gonadal regression period the morphometric parameters were the lowest. Most parameters of lactotrophs in the prepubertal were significantly lower than in the adult males in the reproductive period. In the melatonintreated animals and in castrated animals there was a decrease in %IA, %PDC, and no.cell/RA. In the females, the morphometric parameters increased at the end of pregnancy. Non-pregnant females exhibited a higher immunopositive area and number, but a smaller size of cells than males. Our results showed that in the adult male viscacha, lactotrophs vary seasonally, probably due to the photoperiod effect through melatonin. Besides the changes observed after castration, in prepubertal animals, in adults of different sex, and during pregnancy suggest that the gonadal steroid hormones might modify the lactotrophs activity. Anat Rec, 293:150-161, 2010. V V C 2010 Wiley-Liss, Inc.

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Effect of hypoprolactinaemia and hyperprolactinaemia on LH secretion, endocrine function of testes and structure of seminiferous tubules in boars

Cited by 17 publications

References 4 publications

Effects of the dopamine agonist cabergoline on the pulsatile and TRH-induced secretion of prolactin, LH, and testosterone in male beagle dogs

Effects of the dopamine agonist cabergoline on the pulsatile and TRH-induced secretion of prolactin, LH, and testosterone in male beagle dogs

Effects of Short‐term Hyper‐ and Hypoprolactinaemia on Hormones of the Pituitary, Gonad and ‐Thyroid Axis and on Semen Quality in Male Beagles

Morphological and Morphometric Changes of Pituitary Lactotrophs of Viscacha (Lagostomus maximus maximus) in Relation to Reproductive Cycle, Age, and Sex

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