Estrogen regulates the serum level of phosphorylated prolactin in mice

Phosphorylated prolactin (PPRL) is considered to be the most quantitatively important post-translationally modified form of prolactin (PRL) in rodents. We recently detected two different types of PPRL in the mouse pituitary gland; one was phosphorylated at serine and the other was phosphorylated at serine/threonine. Furthermore, we showed that there are obvious differences in the ratios between PPRLs and non-phosphorylated PRL in the pituitary gland based on age and sex and that estrogen influences PRL phosphorylation at serine in female mice. In the present study, we examined whether estradiol (E2) increases serine PPRL in the male pituitary gland in the same manner as in the female pituitary gland and examined whether PPRL is released into serum. We first determined the relative amounts of intrapituitary PPRLs in male mice under different pharmacological conditions that increased PRL secretion. The results indicated that treatment with E2 increases serine PPRL. We then performed two-dimensional electrophoresis and immunoblotting analysis after immunoprecipitation with anti-mouse PRL antibody using male and female sera under different pharmacological conditions that increased PRL secretion. The results of this experiment indicated that there were PRLs phosphorylated at serine and serine/threonine in the female serum but not in the male serum. The levels of PPRLs in sera were greatly increased with the E2 treatment for both male and female sera. Furthermore, we examined the effect of E2 on PPRL synthesis in cultured male pituitary glands. In this experiment, we observed increased serine PPRL synthesis and stronger immunohistochemical staining of PRL cells with E2 treatment. These findings suggested that serine PPRL synthesis and secretion were influenced by estrogen.     

Regulation of growth hormone expression by thyrotropin-releasing hormone through the pituitary-specific transcription factor Pit-1 in chicken pituitary

Pit-1 is a pituitary-specific POU-domain DNA binding factor, which binds to and trans-activates promoters of growth hormone- (GH), prolactin- (PRL) and thyroid stimulating hormone beta- (TSHbeta) encoding genes. Pit-1 has been identified in several mammalian and avian species. Thyrotropin-releasing hormone (TRH) is located in the hypothalamus and it stimulates TSH, GH and PRL release from the pituitary gland. In the present study, we successfully developed a competitive RT-PCR for the detection of Pit-1 expression in the chicken pituitary, that was sensitive enough to detect picogram levels of Pit-1 mRNA. Applying this method, the effect of TRH injections on Pit-1 mRNA expression was determined in the pituitary of chick embryos and growing chicks. In both 18-day-old embryos and 10-day-old male chicks the Pit-1 mRNA expression was significantly increased following TRH injection, thereby indicating that the stimulatory effects of TRH on several pituitary hormones is mediated via its effect on Pit-1 expression. Therefore, a semi-quantitative RT-PCR method was used to detect possible changes in GH levels. TRH affected the GH mRNA levels at both developmental stages. These results, combined with the data on Pit-1 mRNA expression, indicate that Pit-1 has a role in mediating the stimulatory effects of TRH on pituitary hormones like GH.     

The chicken pituitary-specific transcription factor PIT-1 is involved in the hypothalamic regulation of pituitary hormones

Pit-1 is a pituitary-specific POU-domain DNA binding factor, which binds to and trans-activates promoters of growth hormone- (GH), prolactin- (PRL) and thyroid stimulating hormone-beta- (TSHbeta) encoding genes. Thyrotropin-releasing hormone (TRH) is located in the hypothalamus and stimulates TSH, GH and PRL release from the pituitary gland. In the present study, we successfully used the cell aggregate culture system for chicken pituitary cells to study the effect of TRH administration on the ggPit-l* (chicken Pit-1), GH and TSHbeta mRNA expression in vitro. In pituitary cell aggregates of 11-day-old male broiler chicks the ggPit-l * mRNA expression was significantly increased following TRH administration, indicating that the stimulatory effects of TRH on several pituitary hormones are mediated via its effect on the ggPit-l* gene expression. Therefore, a semiquantitative RT-PCR method was used to detect possible changes in GH and TSHbeta mRNA levels. TRH affected both the GH and TSHbeta mRNA levels. The results of this in vitro study reveal that ggPit-1 * has a role in mediating the stimulatory effects of TRH on pituitary hormones like GH and TSHbeta in the chicken pituitary.     

催乳素及其受体在青年公羊驼皮肤中分布的研究

羊驼是一种经济价值很高的毛用动物，研究包括激素在内的各种因素对羊驼毛生长的调控极为重要。作者采用基因芯片杂交技术发现青年公羊驼皮肤中不仅存在PRL及其受体基因，而且还存在PRL相关蛋白基因，提示羊驼皮肤是PRL的一个垂体外合成部位，同时羊驼皮肤还可以合成PRL相关蛋白及PRL受体；通过荧光定量分析比较，认为羊驼皮肤合成的PRL是极少量的，垂体是PRL合成的主要部位；通过免疫组织化学技术确定PRL及其受体蛋白主要分布在羊驼毛囊上皮根鞘、表皮、皮脂腺等，提示PRL对羊驼皮肤及其衍生物可能以内分泌、自分泌和旁分泌的方式发挥作用。     

Thirteen-weeks subcutaneous treatment with high dose of natural sex hormones in rats with special reference to their effect on the pituitary-gonadal axis. I. Oestradiol

A high dose of oestradiol (0.3 mg/kg/day) was administrated subcutaneously to male and female rats daily for 13 weeks. The effects of hormonal treatment on various parameters were studied. The results revealed that treatment with oestradiol resulted in alopecia, retarded hair regrowth, decreased body weight and food consumption and reduced Hb, PCV and total RBCs. Neutrophilic leucocytosis, elevated ESR, and decreased blood glucose levels were also observed. Atrophy of the ovaries, testes and secondary sex organs was also recorded. The uterus of the oestradiol treated rats displayed endometrial epithelial cell hyperplasia and hypertrophy of the myometrium. The pituitary gland of the rats with oestradiol had a significant increase in the number of PRL and ACTH cells together with cytological criteria indicative of increased secretory activity; the gonadotropin-producing cells showed involutionary changes. The mammary glands of the oestradiol treated rats showed maximal stromal and ductal proliferation and minimal acinar proliferation.     

Histological and histochemical studies on the lingual, preglottal and laryngeal salivary glands of the Japanese quail (Coturnix coturnix japonica) at the post-hatching period

The postnatal development and histochemistry of mucins of the lingual, preglottal and laryngeal glands in the quails were investigated by means of light microscopy using specific staining for complex carbohydrates. In this study, the tongues were taken from female and male quails from day 1 to day 60 after hatching. The salivary glands in quail's tongue comprised the lingual gland, with lateral and medial (paraentoglossal gland) portions that differ in morphology and histochemical staining, and the preglottal gland, with two lateral portions and one medial portion. The medial portion of the preglottal gland, which extended to the row of the laryngeal papillae on each side of the glottis, was described as the laryngeal gland. The salivary glands were present at hatching and their cells were functionally mature and secreted mucins. In quail of all ages, the histochemical reactions revealed that the cytoplasms of the secretory cells of the preglottal, laryngeal and paraentoglossal gland (medial portion of lingual gland) contained sialomucins and weakly sulphated epithelial mucins. Neutral mucins were absent in the paraentoglossal gland, while a small amount of neutral mucins was present in other glands. The mucins with vicinal diol groups, sialomucins and weakly sulphated epithelial mucins were mixed within the secretory cells of all the glands. All the histochemical reactions were restricted to the supranuclear regions of the secretory cells within the lateral portion of the lingual gland. In conclusion, the contents of mucins in the lingual, preglottal and laryngeal glands varied between different age groups, however, no differences in the glands' histochemistry between male and female quails were observed.     

Salsolinol is present in the bovine posterior pituitary gland and stimulates the release of prolactin both in vivo and in vitro in ruminants

The aims of the present study were to determine whether salsolinol (SAL), a dopamine-related compound, is present in the bovine posterior pituitary (PP) gland, and to clarify the effect of SAL on the secretion of prolactin (PRL) in ruminants. SAL was detected in extract of bovine PP gland using high-pressure liquid chromatography with electrochemical detection (HPLC-EC). A single intravenous (i.v.) injection of SAL (5 and 10mg/kg body weight) significantly and dose-dependently stimulated the release of PRL in goats (P<0.05). Plasma PRL levels reached a peak 10min after the injection, then gradually returned to basal values in 60-80min. The PRL-releasing pattern was similar to that in response to sulpiride (a dopamine receptor antagonist). The intracerebroventricular (i.c.v.) injection of 1mg of SAL had no significant effect on the release of PRL in calves, however, 5mg significantly stimulated the release (P<0.05) with peak values reached 30-40min after the injection. Moreover, SAL significantly stimulated the release of PRL from cultured bovine anterior pituitary cells at doses of 10(-6) and 10(-5)M, compared to control cells (P<0.05). Taken together, our data clearly show that SAL is present in extract of the PP gland of ruminants, and has PRL-releasing activity both in vivo and in vitro. Therefore, this endogenous compound is a strong candidate for the factor having PRL-releasing activity that has been previously detected in extract of the bovine PP gland.     

Studies on the functional relationship between thyroid, adrenal and gonadal hormones

In order to clarify the functional relationship between thyroid, adrenal and gonadal hormones, hypothyroidism was induced by administration of thiuoracil in adult male and female rats, and the effects of hypothyroidism on the adrenal and the gonadal axes were investigated in the present study. 1. The functional relationship between thyroid and adrenal hormones: Adrenal weights and corticosterone were lowered, whereas the secretion of ACTH, corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) increased in hypothyroid rats compared to euthyroid rats. These results indicate that hypothyroidism causes adrenal dysfunction directly and results in hypersecretion of CRH and AVP from the hypothalamus. 2. The functional relationship between thyroid and gonadal hormones: The pituitary response to LHRH was lowered, whereas the testicular response to hCG was not changed in hypothyroid rats. Hypothyroidism suppressed copulatory behavior in male rats. These results suggest that hypothyroidism probably causes dysfunction in gonadal axis at the hypothalamic-pituitary level in male rats. In adult female rats, hypothyroidism inhibited the follicular development accompanied estradiol secretion, whereas plasma concentrations of progesterone and prolactin (PRL) increased in hypothyroid female rats. Hypothyroidism significantly increased the pituitary content of vasoactive intestinal peptide (VIP) though it did not affect dopamine synthesis. These results suggest that hypothyroidism increases pituitary content of VIP and this increased level of VIP likely affects PRL secretion in a paracrine or autocrine manner. In female rats, inhibition of gonadal function in hypothyroid rats mediated by hyperprolactinemia in addition to hypersecretion of endogenous CRH.     

Development, validation, and utilization of a novel antibody specific to the type III chicken gonadotropin-releasing hormone receptor

Two gonadotropin-releasing hormone receptors (GnRH-Rs) have been characterized in chickens to date: cGnRH-R-I and cGnRH-R-III, with cGnRH-R-III being the predominant pituitary form. The purpose of the present study was to first validate a novel antibody for the specific detection of cGnRH-R-III and second, using this antibody, detect changes in cGnRH-R-III protein levels in the pituitary gland of male and female chickens during a reproductive cycle. The localization of cGnRH-R-III within the anterior pituitary gland was also determined. Western blotting of pituitary extracts and transiently transfected COS-7 cell lysates revealed that our antibody is highly specific to cGnRH-R-III protein. Similarly, when used in immunocytochemistry, this antibody specifically detects cells expressing cGnRH-R-III and not cGnRH-R-I. Western blot analyses of chicken pituitary gland homogenates show that cGnRH-R-III protein levels are significantly greater in sexually mature birds than in immature birds or birds at the end of a reproductive cycle (P < 0.0001). A similar pattern was observed for both males and females. Additionally, the antibody was able to detect cGnRH-R-III in cells along the periphery of the cephalic and caudal lobes of the anterior pituitary where the cells containing the gonadotropins are located. In summary, we successfully validated a novel antibody to cGnRH-R-III and showed levels of cGnRH-R-III protein in the pituitary fluctuate with respect to the reproductive status in both male and female chickens.     

Identification and characterisation of side population cells in the canine pituitary gland

To date, stem/progenitor cells have not been identified in the canine pituitary gland. Cells that efficiently exclude the vital dye Hoechst 33342 can be visualised and identified using fluorescence activated cell sorting (FACS) as a 'side population' (SP), distinct from the main population (MP). Such SPs have been identified in several tissues and display stem/progenitor cell characteristics. In this study, a small SP (1.3%, n=6) was detected in the anterior pituitary glands of healthy dogs. Quantitative PCR indicated significantly higher expression of CD34 and Thy1 in this SP, but no differences in the expression of CD133, Bmi-1, Axin2 or Shh. Pro-opiomelanocortin (POMC) and Lhx3 expression were significantly higher in the MP than in the SP, but no differences in the expression of Tpit, GH or PRL were found. The study demonstrated the existence of an SP of cells in the normal canine pituitary gland, encompassing cells with stem cell characteristics and without POMC expression.     

MENSURATION OF THE NORMAL PITUITARY GLAND FROM MAGNETIC RESONANCE IMAGES IN 96 DOGS

The pituitary gland was measured from transverse magnetic resonance T1-weighted images after Gadolinium administration in 96 dogs weighing from 13 to 45 kg. The measurements were done by hand with calipers. The mean (+/- standard deviation) pituitary gland height was 5.1 mm (+/-0.9 mm). The mean width was 6.4 mm (+/- 1.1 mm). The correlation coefficient between pituitary and brain measurements, between pituitary measurement and body weight, and brain measurements and body weight was 0.0 to 0.3. A hyperintense region was present on T1-weighted images in the center of the pituitary gland in 64% of the dogs. At necropsy the pituitary glands were grossly and histologically normal. No pituitary gland measurements were performed at necropsy.     

维生素、矿物质与能量蛋白质水平对浙东白鹅母鹅繁殖性能、血液生殖激素浓度及生殖轴相关基因mRNA相对表达量的影响

本试验通过在饲粮中添加维生素与矿物质、调整饲粮能量蛋白质水平,旨在研究其对浙东白鹅母鹅繁殖性能、血液生殖激素浓度和生殖轴相关基因mRNA相对表达量的影响.选择138只月龄相近的浙东白鹅种母鹅,按体重相近原则分为3组,分别饲喂不同的饲粮,试验期150 d,测定繁殖性能(平均产蛋数、平均蛋重、受精率和孵化率)、血液生殖激素[卵泡刺激素(FSH)、促黄体生成素(LH)、孕酮(P4)、雌二醇(E2)、催乳素(PRL)]浓度和生殖轴相关基因[促性腺激素释放激素(GnRH)、卵泡刺激素-β(FSHβ)、雌激素受体1(ESR1)、雌激素受体2(ESR2)、卵泡刺激素受体(FSHR)、催乳素(PRL)、催乳素受体(PRLR)] mRNA相对表达量的变化.结果表明:1)添加维生素与矿物质可显著提高浙东白鹅母鹅第1产蛋周期平均蛋重和受精率(P＜0.05);提高第2产蛋周期内血液FSH和P4的浓度,降低LH浓度,改变E2、P4和PRL浓度波动(P＜0.05);下调下丘脑PRLR、垂体PRL和卵巢PRLR基因的mRNA相对表达量(P＜0.05),上调卵巢ESR2基因的mRNA相对表达量(P＜0.05).2)调整饲粮能量蛋白质水平可显著提高浙东白鹅母鹅第2产蛋周期平均蛋重(P＜0.05);提高浙东白鹅第2产蛋周期内血液LH浓度,降低FSH浓度,改变E2和P4浓度波动(P＜0.05);上调下丘脑GnRH、垂体PRL和PRLR基因的mRNA相对表达量(P＜0.05),下调卵巢FSHR基因的mRNA相对表达量(P＜0.05).由此得出,添加维生素与矿物质、调整饲粮能量蛋白质水平可通过影响产蛋周期内部分血液生殖激素浓度和波动,局部调节生殖轴相关基因的mRNA相对表达量,改善浙东白鹅母鹅的繁殖性能.     

Renin in Exocrine Glands of Different Mouse Strains

The renin-angiotensin system (RAS) controls the regulation of blood pressure and water-mineral balance. Recently, renin has been reported to be synthesized and secreted outside the kidney. The present study investigated immunohistochemically the distribution of renin in exocrine glands, i.e. salivary glands and coagulating glands, in male mice of 13 strains. In some strains, renin was detected in the sublingual and submandibular salivary glands, but not in the parotid glands. It was restricted to the striated or granular portions of excretory ducts. In coagulating glands, variable staining patterns were found. These results demonstrate the existence of variations in renin content in mouse strains and offered a selection of mouse strains for investigation of exocrine gland renin.     

Interactions of amino acids and hormones regulate the balance between growth and milk protein synthesis in lactating rats fed diets differing in protein content

Insulin-like growth factor-I (IGF-I), growth hormone (GH), and prolactin (PRL) play important roles in milk protein synthesis, and their plasma concentrations were reported to be affected by dietary protein intake. To investigate the relationship between circulating amino acid (AA) and concentrations of these hormones, 18 Wistar rats aged 14 wk were assigned to a low (LP; 9% protein), standard (SP; 21% protein), or high-protein (HP; 35% protein) diet from parturition through day 15 of lactation. Plasma, liver, pituitary gland, skeletal muscle, and mammary gland samples were collected at the end of treatment. Circulating and hepatic IGF-I concentrations increased linearly with elevated dietary protein concentrations (P < 0.0001). Rats receiving the HP diet had higher circulating GH (P < 0.01) and pituitary PRL concentrations (P < 0.0001) but lower pituitary GH concentration (P < 0.0001) relative to those in rats receiving the LP and SP diets. Pearson correlation test performed on composed data across treatments showed that several circulating AAs were correlated with circulating and tissue concentrations of IGF-I, GH, and PRL. Multiple linear regression analyses identified Leu, Gln, Ala, Gly, and Arg as the main AAs associated with hormone responses (R² = 0.37 ~ 0.80; P < 0.05). Rats fed the LP and HP diets had greater Igf1 and Ghr gene expression in skeletal muscle than those fed the SP diets (P < 0.01). However, LP treatment decreased Prlr mRNA abundance in mammary glands as compared with the SP and HP treatments (P < 0.05). The HP diets increased AA transporter expression (P < 0.01) but decreased mammalian target of rapamycin (P < 0.05) and 70 kDa ribosomal protein S6 kinase 1 (P < 0.01) phosphorylation in mammary glands as compared with the LP and SP diets. The results of the present study suggested that several circulating AAs mediated the effects of dietary protein supply on concentrations of IGF-I, GH, and PRL, which in turn altered the metabolism status in peripheral tissues including the lactating mammary glands.     

Histochemical studies on the dependence of secretory function of the major vestibular gland (Bartholin's gland) on ovarian steroid hormones in the cat.

The dependency of the secretory function of the feline major vestibular gland (Bartholin's gland) on the ovarian steroid hormones was studied histochemically. After estrogen (estradiol-17 beta or diethylstilbestrol), progesterone or a combination of these was administered to cats which were previously ovariohysterectomized, the major vestibular glands were removed, embedded in paraffin, sectioned, and stained by alcian blue, periodic acid-Schiff or peroxidase-labeled lectin (peanut agglutinin and wheat germ agglutinin). The vividly positive reactions to the stainings applied were observed in the secretory epithelial cells of the major vestibular glands in the estrogen treated animals. The dependency of the secretory function of the major vestibular glands on the estrogen was demonstrated in this study.     

FSH分泌细胞在皖西白鹅脑垂体中的分布与定位

采用免疫组化SABC法并结合DAB显色技术时皖西白鹩脑垂体结构和促卵泡素(follicular stimulating hormone,FSH)分泌细胞进行了研究和定位.结果发现,皖西白鹅的垂体前叶由远侧部和结节部构成,没有中间部.垂体FSH免疫阳性细胞分布广泛,但前叶远侧部分布较多,从而表明皖西白鹅整个垂体都有FSH分泌,主要分泌部位在垂体前叶的远侧部.     

Pituitary progesterone receptor expression and plasma gonadotrophin concentrations in the reproductively dysfunctional mutant restricted ovulator chicken

Female mutant restricted ovulator (RO) chickens of the White Leghorn strain carry a naturally occurring single nucleotide mutation in the very low density lipoprotein receptor (VLDLR) gene. Due to this mutation, RO hens fail to express a functional VLDLR protein on the oocyte membrane, which results in an impaired uptake of circulating yolk precursor macromolecules. Mutant RO hens subsequently develop hyperlipidemia and generally fail to lay eggs due to follicular atresia. Since RO hens also reportedly have three-fold higher basal plasma estrogen concentrations, combined with four-fold lower levels of circulating progesterone as compared to wild-type (WT) hens, we hypothesized that RO hens would have an increased abundance of pituitary progesterone receptor (PR) mRNA and PR isoforms A and B as well as alterations in circulating gonadotrophin levels. Quantitative PCR assays revealed significantly greater (P相似文献   

Assessment of the accuracy of computed tomography for measurement of normal equine pituitary glands

OBJECTIVE: To describe the anatomic features of the pituitary gland region in horses via computed tomography (CT) and determine the accuracy of CT for estimating normal equine pituitary gland dimensions. ANIMALS: 25 adult horses with no clinical signs of pituitary disease. PROCEDURE: Transverse CT images and gross transverse tissue sections were compared in 2 horses. Contrast-enhanced CT of the pituitary gland region was performed postmortem in 23 horses with 4 slice thickness and interval settings (10-mm contiguous or overlapping slices and 4-mm contiguous or overlapping slices). Gross and CT estimates of pituitary gland dimensions were compared via ANOVA. Accuracy of CT estimates was calculated with gross pituitary gland measurements as the known value. RESULTS: Pituitary glands were located between the temporomandibular joints and had contrast enhancement. Mean gross dimensions were length, 2.11 cm; width, 2.16 cm; height, 0.98 cm; and volume, 2.66 cm3. Gross measurements and CT estimates of pituitary gland length from 10-mm contiguous and overlapping slices did not differ. Gross measurements and CT estimates of pituitary gland width from 4-mm contiguous and overlapping slices did not differ. Estimates of height and volume from all CT techniques differed from gross measurements. Accuracies for CT estimates were length, 88 to 99%; width, 81 to 92%; height, 58 to 71%; and volume, 43 to 55%. CONCLUSIONS AND CLINICAL RELEVANCE: Accuracy of estimates of pituitary gland dimension in horses varied with CT scanning technique; via CT estimates of length and width of glands were more accurate than estimates of height or volume.