The maintenance of gestation and the initiation of lactation in the mouse in the absence of pituitary prolactin

Potential contribution of alpha-fetoprotein level to biomarker of pregnancy outcome in Asian elephants

Alpha-fetoprotein (AFP) is a structural serum glycoprotein that plays vital roles in reproduction and mammalian development. Analysis of serum prolactin (PRL) is considered one of the useful methods for diagnosing pregnancy in Asian elephants. However, the expression profiles of AFP in pregnant and nonpregnant Asian elephants remain unclear, nor is the relationship with PRL. In this study, serum seven gonadal hormones and AFP in three pregnant and seven nonpregnant Asian elephants were analysed by via radioimmunoassay (RIA) and enzyme-linked immunosorbent (ELISA) assay. We found that the mean (±SD) concentration of prolactin (PRL) in pregnant (136.782 ± 30.987 ng/mL) elephants was significantly higher than that in nonpregnant elephants (52.803 ± 21.070 ng/mL; p ≤ 0.0005). The mean (±SD) concentration of AFP in pregnant elephants (11.598 ± 0.824 ng/mL) was significantly higher than that in nonpregnant elephants (7.200 ± 2.283 ng/mL; p ≤ 0.05). Furthermore, the AFP concentration was positively correlated with the PRL concentration in the 10 Asian elephants studied. In conclusion, our findings suggest that serum AFP concentration is a potential biomarker of pregnancy outcomes in Asian elephants.

Sirh7/Ldoc1 knockout mice exhibit placental P4 overproduction and delayed parturition

Sirh7/Ldoc1 [sushi-ichi retrotransposon homolog 7/leucine zipper, downregulated in cancer 1, also called mammalian retrotransposon-derived 7 (Mart7)] is one of the newly acquired genes from LTR retrotransposons in eutherian mammals. Interestingly, Sirh7/Ldoc1 knockout (KO) mice exhibited abnormal placental cell differentiation/maturation, leading to an overproduction of placental progesterone (P4) and placental lactogen 1 (PL1) from trophoblast giant cells (TGCs). The placenta is an organ that is essential for mammalian viviparity and plays a major endocrinological role during pregnancy in addition to providing nutrients and oxygen to the fetus. P4 is an essential hormone in the preparation and maintenance of pregnancy and the determination of the timing of parturition in mammals; however, the biological significance of placental P4 in rodents is not properly recognized. Here, we demonstrate that mouse placentas do produce P4 in mid-gestation, coincident with a temporal reduction in ovarian P4, suggesting that it plays a role in the protection of the conceptuses specifically in this period. Pregnant Sirh7/Ldoc1 knockout females also displayed delayed parturition associated with a low pup weaning rate. All these results suggest that Sirh7/Ldoc1 has undergone positive selection during eutherian evolution as a eutherian-specific acquired gene because it impacts reproductive fitness via the regulation of placental endocrine function.

Milk-borne prolactin and neonatal development

Milk is primarily regarded as a food furnishing essential nutrients for infant growth and development, but milk can also serve as a vehicle for mother to neonate transfer of molecules that regulate development. A wide array of biologically active compounds such as hormones, cytokines and enzymes are present in milk, especially early milk. The premise that prolactin (PRL) in milk is an important and possibly essential developmental factor for the newborn is explored. Both PRL and structurally modified isoforms are abundant in early milk and gradually diminish with the progression of lactation. Milk PRL is absorbed and biologically active in the neonate. Assays of PRL variants, experimental paradigms to test them as developmental regulators and the body of evidence supporting the hypothesis that milk PRL regulates differentiation and maturation of neonatal neuroendocrine, reproductive, and immune systems is presented.

Immunocytochemical effects of thyroxine stimulation on the adenohypophysis of dwarf (dw) mutant mice

The effects of dietary thyroxine on the immunoreactivity of cells in the pars distalis of the adenohypophysis in dwarf (dw/dw) mice were determined by ultrastructural immunocytochemistry. In nontreated dwarfs only adrenocorticotropic hormone (ACTH) cells and luteinizing hormone (LH) cells showed positive reactions to their respective antibodies, whereas no cells showed immunoreactivity to antibodies to growth hormone (GH), thyroid-stimulating hormone (TSH), or prolactin (Prl). In dwarfs supplemented postnatally with dietary thyroxine for 9 wks, the treatment failed to produce immunoreactive GH, TSH or Prl cells. However, LH cells became more prominent and fully developed, with denser concentrations of immunoreactive particles overlying the secretory granules than occurred in nontreated dwarfs. In thyroxine-treated dwarfs, ACTH cells were similar in ultrastructural features and immunoreactivity to those in nontreated dwarfs.

Ultrastructural immunocytochemistry of somatotrophs and mammotrophs in embryos of the dwarf mutant mouse

The embryonic development of somatotrophs and mammotrophs in the adenohypophysis in dwarf (dw) mutant mice was studied by means of ultrastructural immunocytochemistry. Embryos at 16-18 days of gestation were removed from litters consisting entirely of dwarf homozygotes obtained from homozygous matings of adult dwarfs in which reproductivity was induced by means of hormone supplementation and renal capsule implants of normal pituitaries. Litters from normal (+/+) matings served as controls. Pituitaries from adult normal and dwarf mice also were removed and processed with the embryonic material. Thin sections were exposed to anti-growth-hormone serum (anti-GH) or to antiprolactin serum (anti-PRL) and processed immunocytochemically with the colloidal gold procedure. In the normal pituitaries, a strong positive reaction to anti-GH occurred in the adult and in embryos as early as 16 days, whereas the reaction to anti-PRL was strong in the adults but relatively weak in the embryos. In dwarf embryonic and adult pituitaries, ambiguous cells showing combinations of features characteristic of somatotrophs and mammotrophs were present. However, neither these cells nor other granulated cells reacted to anti-GH or to anti-PRL, except for a questionable reaction to the latter at 18 days and in the adult. Thus, the dwarf pituitary shows functional as well as morphological abnormalities as early as 16 days of gestation.

Hypothalamic catecholamine histofluorescence in dwarf mice

Brains of growth hormone (GH)- and prolactin (PRL)-deficient Ames (df/df) and Snell (dw/dw) dwarf mice and normal mice of the same strains were examined for catecholamine (CA) histofluorescence, with particular emphasis upon the hypothalamic tuberoinfundibular (A12) (arcuate nucleus/median eminence) region, which plays a role in the regulation of both GH and PRL. Dwarfs and normal animals of both types also were treated with a drug regimen to deplete sequentially neuronal CA stores (reserpine), inhibit CA oxidation (nialamide) and load dopaminergic A12 cells with exogenous transmitter (norepinephrine), in order to test viability and axonal transport capacity of A12 neurons. In both types of dwarfs, compared with normals, fluorescence was markedly reduced in the zona externa of the median eminence, which is normally rich in terminals from A12 neurons. Fluorescence in the median eminence was particularly weak in Ames dwarfs, and A12 perikarya were difficult to discern in this group. Snell dwarfs showed reduced fluorescence of A12 perikarya when compared with the brightly fluorescent perikarya seen in normal mice. In supraoptic and paraventricular nuclei, and in the zona interna of the median eminence, CA fluorescence attributable to NE was comparable among dwarfs and normals; fluorescence of dopaminergic perikarya in substantia nigra was also unaffected in dwarfs. Exogenously administered NE effected enhanced fluorescence of A12 perikarya in normal mice and in Snell dwarfs; NE treatment in the Ames dwarf, however, failed to increase significantly the faint fluorescence of A12 cell bodies. The results indicate that dopaminergic A12 neurons in Snell dwarf mice are present and viable.(ABSTRACT TRUNCATED AT 250 WORDS)

Fine structure of pituitary blood vessels in embryos of the dwarf (dw) mutant mouse

Blood vessels in the pars distalis of the embryonic pituitary gland of the dwarf (dw) mutant mouse were analyzed by means of electron microscopy. Dwarf (dw/dw) embryos ranging in age from 15 through 18 days of gestation were obtained from matings of dwarf homozygotes in which reproductivity was induced by means of hormone supplementation and grafts of normal pituitary to the kidney capsule. Endothelial cells in vessels of the dwarf pituitary were retarded in development as indicated by a retention of macrovesicles and marginal flaps beyond embryonic stages when they normally subside in normal embryos, as well as a lag in the development of endothelial cell attenuations. This retardation may be causally related to the pituitary pathology involving faulty cytodifferentiation of somatotrophs and mammotrophs.

Antifertility efficacy of the plant Aristolochia indica linn on mouse

Two compounds isolated from the alcoholic extract of the roots of Aristolochia indica Linn were tested on day 6 pregnant mice. One of the compounds, p-coumaric acid showed 100% interceptive activity at the single oral dose of 50 mg/kg of body weight. The antifertility efficacy of these two compounds is discussed.

Antifertility effects of the steroid 5 alpha-stigmastane-3 beta, 5, 6 beta-triol 3-monobenzoate on mice

The steroid 5 alpha-stigmastane-3 beta, 5, 6 beta-triol 3-monobenzoate at a dose of 40 mg/kg of body weight has 100% interceptive activity when administered orally in a single dose during 6-7 days of gestation but it has no action on pregnancy if treated on 10th, 13th or 16th day of pregnancy. The interceptive activity of the steroid is lost by simultaneous injection of prolactin, progesterone or LH.

Lack of action of prolactin suppression on the regulation of the human menstrual cycle

Bromocriptin (CB 154) has been found to suppress established lactation at a time when human plasma prolactin (HPRL) concentrations have already returned to the nonpregnant range. This action is due to inhibition of prolactin from the pituitary. It was then thought that a similar degree of inhibition induced during the menstrual cycle may help to uncover other possible biological actions of prolactin. In an attempt to elucidate this question eight breast-feeding mothers and seven normally menstruating volunteers underwent treatment with CB 154, including blood sampling during a sleep period. The dosage was 1 mg., three times daily, for 14 days in the first group and for a whole cycle in the normal volunteers. A control cycle preceded drug administration in the latter group. Prolactin (HPRL), growth hormone (HGH), luteotropin (LH), progesterone (PG), and estradiol (E2) were estimated (mean +/- standard error) along the menstrual cycles in the normal volunteers. HPRL and milk volumes were measured in the breast-feeding women in the base-line period and during treatment. In the postpartum group, basal HPRL had already reached normal levels prior to therapy (10.8 +/- 1.0 ng. per milliliter) and was significantly (p less than 0.002) depressed to 3.7 +/- 0.4 ng. per milliliter by CB 154. This degree of inhibition was effective in suppressing lactation within 24 to 48 hours in all of the subjects in that group. The fall in plasma HPRL from 9.5 +/- 1.5 ng. per milliliter to 3.2 +/- 0.2 ng. per milliliter observed in the normally menstruating women was similar to the one recorded in the breast-feeding group, but the sequence of hormonal changes during the menstrual cycle was not altered by treatment. The overnight study ensured around-the-clock prolactin inhibition. Results indicate no action of prolactin in the regulation of the human menstrual cycle at levels of inhibition at which a biological action of this hormone is clearly suppressed.