The ontogeny of hypothalamic pituitary function in the pig I. Pituitary LH and FSH in the fetus and neonate

McNamara, Michael J.; Vandalem, J. L.; Hennen, Georges; Colenbrander, B.; Macdonald, Alastair A.; Wiel, D Van de; Meijer, J. C.

doi:10.1016/0303-7207(85)90128-5

Cited by 7 publications

(5 citation statements)

References 18 publications

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“…I-FSH increased with gestational age (Table 1). This finding is consistent with that reported for the pig (McNamara, Vandalem, Hennen et al 1985), but differs from that found in human fetuses (Grumbach & Kaplan, 1974;Kaplan & Grumbach, 1976;SilerKhodr & Khodr, 1980). In human females, the pitui¬ tary contents and concentrations of I-FSH peaked at mid-gestation and then declined, whereas in the male fetuses the pituitary contents increased throughout gestation whilst the pituitary concentrations increased until mid-gestation and then declined (Grumbach & Kaplan, 1974;Kaplan & Grumbach, 1976) sheep compared with the human.…”

Section: Discussionsupporting

confidence: 92%

“…In human females, the pitui¬ tary contents and concentrations of I-FSH peaked at mid-gestation and then declined, whereas in the male fetuses the pituitary contents increased throughout gestation whilst the pituitary concentrations increased until mid-gestation and then declined (Grumbach & Kaplan, 1974;Kaplan & Grumbach, 1976) sheep compared with the human. What is common to the human, ovine and porcine fetuses is that the female fetuses have consistently higher concentrations and contents of pituitary FSH than the males of com¬ parable age (Table 1; Grumbach & Kaplan, 1974; Kaplan & Grumbach, 1976;Siler-Khodr & Khodr, 1980;McNamara et al 1985). In the present study, the pattern of B/I ratios for FSH also followed the same trend as that found in the study of human fetuses (Beck-Peccoz et al 1991), with the B/I ratios being lower at mid-gestation com¬ pared with late gestation.…”

Section: Discussionmentioning

confidence: 95%

See 1 more Smart Citation

Bioactive and immunoreactive FSH and immunoreactive inhibin concentrations in the ovine fetus

Phillips¹,

Smith²,

Heath³

et al. 1992

Journal of Endocrinology

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The bioactive (B) and immunoreactive (I) pituitary contents/concentrations of FSH, together with the plasma concentrations of B-FSH, I-FSH and I-inhibin were determined in ovine fetuses at days 55, 75, 90 and 135 of gestation (day 145 = term). The pituitary contents and concentrations of B-FSH and I-FSH increased in both sexes with gestational age. The female fetuses had significantly (P < 0.01) higher pituitary contents/concentrations of B-FSH and I-FSH than the male fetuses at days 75 and 135. The pituitary B/I ratios of FSH were not significantly different with age or sex. The plasma concentrations of B-FSH remained relatively constant from days 75 to 135, with no significant differences between sexes or with age. In contrast, the plasma concentrations of I-FSH reached a peak at day 90 and then declined towards term in both sexes. At all gestational ages except day 55, the female fetuses had significantly (P < 0.05) higher plasma concentrations of I-FSH than the males. In both sexes, the plasma B/I ratios of FSH were lowest at day 90 and had increased again by day 135, with the male fetuses having significantly (P < 0.05) higher B/I ratios compared with the female group at days 75 and 135 but not at day 90. At all gestational ages, the plasma concentrations of I-inhibin declined throughout gestation in the female fetuses, whereas in the males they reached a nadir at day 75 and then increased towards term. The concentrations of I-inhibin were significantly (P < 0.01) higher in the male fetuses compared with the females.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 95%

Bioactive and immunoreactive FSH and immunoreactive inhibin concentrations in the ovine fetus

Phillips¹,

Smith²,

Heath³

et al. 1992

Journal of Endocrinology

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“…In contrast to the constant level of LH secretion, the FSH secretion rate increased during the first 3 weeks after birth. These results are in agreement with those of a previous study (Colenbrander et al 1982 ) and are supported by data on pituitary content of gonadotrophins (McNamara, Vandalem, Hennen et al 1985).…”

Section: Discussionsupporting

confidence: 95%

“…The present data on neonatal gonadotrophin secre¬ tions, as well as our previous results on LH and FSH pituitary content during the same period (McNamara et al 1985), and the demonstration of the existence of significant amounts of gonadotrophin-binding sites in the testes of neonates, support the hypothesis that the perinatal phase of testicular development is under the control of the pituitary (Colenbrander et al 1979).…”

Section: Discussionsupporting

confidence: 88%

Developmental changes in gonadotrophins and testicular gonadotrophin receptors in the pig, from neonatal to adult life

Vandalem¹,

McNamara²,

Petit³

et al. 1986

Journal of Endocrinology

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Changes in the concentrations of LH and FSH testicular receptors have been studied in the pig, from neonatal to adult life, and correlated with blood LH, FSH and testosterone concentrations. Quantification of gonadotrophin receptors was performed in equilibrium binding studies, using homologous systems. The presence of high-affinity binding sites for LH and FSH (association constant (Ka): LH approximately 20 litres/nmol; FSH approximately 10 litres/nmol) was demonstrated in the testes of all animals studied. The apparent affinity of LH and FSH receptors did not change significantly with age. During the first weeks of life, there was a transient rise in LH receptor content, reaching a maximum of 8.7 +/- 2.2 (mean +/- S.E.M.) pmol/g testis at 24 days of age. This was correlated with a peak in testosterone secretion and reflects the second wave of interstitial cell proliferation in the pig. A second increase in the number of LH receptors occurred after 12 weeks of age and corresponds to pubertal maturation and final differentiation of adult Leydig cells. During this period, circulating concentrations of testosterone markedly increased without any significant variation in LH blood levels, suggesting a change in testicular sensitivity to LH in the maturing pig. A continuous increase in FSH receptor content was observed from the neonatal to the adult pig. This increase occurred in two phases. During the first 2 months of life, the increase in the number of FSH receptors exceeded that of testis growth rate and resulted in an increase in FSH receptor concentrations which reached a peak at 12.1 +/- 1.8 pmol/g testis, at week 9.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Thus, the lack of the GnRH-dependent induction of FSHβ in male fetal pituitary seems to be due to the shortage of GnRH receptor in the FSH-producing cells. In accordance with above pieces of information, the concentrations of serum and pituitary FSH in male fetuses are lower compared with female fetuses (Aubert et al, 1985;McNamara et al, 1985;Granz et al, 1997;Takeda et al, 2009). Furthermore, the magnitude of stimuli-induced FSH synthesis is lesser than that of LH synthesis, and the turnover rate of FSH is greater than that of LH (Apfelbaum and Taleisnik, 1976;Muyan et al, 1994).…”

Section: Discussionsupporting

confidence: 53%

2,3,7,8-Tetrachlorodibenzo-p-dioxin potentially attenuates the gene expression of pituitary gonadotropin .BETA.-subunits in a fetal age-specific fashion: a comparative study using cultured pituitaries

et al. 2011

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-Our previous studies have demonstrated that maternal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes a reduction in gonadotropin biosynthesis in the fetal pituitary, resulting in the attenuated expression of steroidogenic proteins in the fetal gonads and the impairment of sexual behaviors in adulthood. However, the mechanism of the attenuation remains unknown. To address this issue, we investigated whether TCDD affects the pituitary production of gonadotropins, using cultured pituitary. In the absence of gonadotropin-releasing hormone (GnRH), a regulator of gonadotropin biosynthesis, TCDD did not affect the expression of gonadotropin mRNAs both in fetal and postnatal pituitaries. On the other hand, in the presence of GnRH, TCDD interfered with the synthesis of gonadotropin β-subunit mRNAs only in the fetal pituitary. A protein kinase C (PKC) activator (phorbol 12-myristate 13-acetate) and a PKA activator (8-bromoadenosine-3' 5'-cyclic monophosphate) induced the expression of gonadotropin mRNAs in the fetal pituitary. Among the subunits, only the induction of β-subunit was reduced by TCDD treatment. These results suggest that TCDD reduces gonadotropin biosynthesis via damage to GnRH-stimulated PKC and PKA signaling in a β-subunit-and fetal age-specific manner.

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The ontogeny of hypothalamic pituitary function in the pig I. Pituitary LH and FSH in the fetus and neonate

Cited by 7 publications

References 18 publications

Bioactive and immunoreactive FSH and immunoreactive inhibin concentrations in the ovine fetus

Bioactive and immunoreactive FSH and immunoreactive inhibin concentrations in the ovine fetus

Developmental changes in gonadotrophins and testicular gonadotrophin receptors in the pig, from neonatal to adult life

2,3,7,8-Tetrachlorodibenzo-p-dioxin potentially attenuates the gene expression of pituitary gonadotropin .BETA.-subunits in a fetal age-specific fashion: a comparative study using cultured pituitaries

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