Effect of ouabain on the lactogenic action of prolactin and on the level of mammary prolactin receptors

Ouabain added to the culture medium of rabbit mammary gland inhibits prolactin action on the initiation of lactose and casein synthesis. The degree of inhibition is a function of the ouabain concentration in the medium. Likewise, ouabain blocks the accumulation of casein mRNA supported by prolactin. In addition, ouabain provokes a rapid disappearance of prolactin receptors. Conversely prolactin keeps its capacity to enhance the concentration of casein mRNA and the parallel casein synthesis when K+ ions are totally absent from the culture medium. These results suggest that although prolactin induces a modification of the K+/Na+ ratio in the mammary cell and ouabain prevents this effect of prolactin, the inhibitory action of ouabain on lactogenesis can be explained essentially by its effect on the hormone receptors.     

Immunoreactive material resembling ovine prolactin in perikarya and nerve terminals of the rat hypothalamus

Summary The presence of prolactin (PRL)-like material is demonstrated in the brain of rats with the aid of anti-ovine PRL (oPRL) IgG as primary antibody in the unlabeled antibody-enzyme method. Immunoreactive deposits are visualized as an intraneuronal constituent with a widespread distribution in the hypothalamus and neural lobe of the pituitary. Dense networks of reactive nerve terminals derived from two prominent fibre tracts, a ventral (VHT) and a dorsal hypothalamo-neurohypophysial tract (DHT) are seen. The VHT is confined to the median eminence and pars oralis tuberis, the DHT to the pars caudalis tuberis. Both fibre tracts pass through the infundibular stalk into the neural lobe. The origin of the immunoreactive nerve terminals can be elucidated only to some extent. The VHT gives off beaded fibres entering the ependymal and glandular layer of the median eminence. Immunoreactive perikarya are observed in the supraoptic nucleus, the paraventricular nucleus, the anterior hypothalamic nucleus, the anterior commissural nucleus, the preoptic nucleus and the interstitial nucleus of the stria terminalis. A few of the immunoreactive perikarya are observed in close connection with brain vessels and the ependymal cells of the third ventricle. The results indicate that the anti-oPRL has a unique region specificity implying that only a segment of the mammalian PRL molecule is present in these nuclei of the brain. Fragments of PRL may function as neuromodulators or neurotransmitters in the rat brain.We are indebted to Dr. Mogens Hammer, Rigshospitalet, Copenhagen for the gift of Arg-VP and anti-VP, and to NIAMDD for the gift of ovine PRL, ratPRL, anti-rPRL, anti-hPRL and bovineSTH     

Differential seminal plasma proteome signatures of acute lymphoblastic leukemia survivors

With advances in therapeutic methods, there is a high survival rate among leukemia patients, of an extent more than 80%. However, chemotherapeutic drugs used to treat these patients have adverse effects on their overall health profile including fertility. The primary aim of this study was to identify differentially expressed proteins in seminal plasma of acute lymphoblastic leukemia (ALL) survivors compared to age-matched healthy controls, which can provide molecular basis of idiopathic infertility in such survivors. Differential proteome profiling was performed by 2D–differential in-gel electrophoresis, protein spots were identified by mass spectrometry and selective differentially expressed proteins (DEPs) were validated by western blotting and ELISA method. Out of eight DEPs identified, five proteins (isocitrate dehydrogenase 1, semenogelin 1, lactoferrin, prolactin-inducible protein, and human serum albumin) were upregulated and three (pepsinogen, prostate specific antigen and prostatic acid phosphatase) were downregulated. Expression profiles of these proteins are suggestive of reduction in semen quality in ALL survivors and can further be explored to determine their fertility status.     

乳房肥大乳腺组织中泌乳素及其受体的表达

目的:研究泌乳素(PRL)及其受体(PRLR)在乳房肥大和正常体积乳房中的表达情况,探讨乳腺组织中PRL、PRLR的表达与乳房肥大的相关性,为乳房肥大的治疗提供方向。方法:收集2013年1月~2013年4月第四军医大学西京医院26例乳房肥大患者和16例因单纯乳房下垂行乳房悬吊术患者的乳腺组织,采用免疫组织化学法检测乳腺组织标本中PRL和PRLR的表达。结果:PRL在乳房肥大组和正常体积乳房组乳腺组织中的阳性细胞率分别为88.46℅和56.25℅,两组比较差异有统计学意义(P0.05),且两组的PRL阳性的细胞面积、平均光密度值和累积光密度值均有统计学差异(P0.05)。乳房肥大组和正常体积乳房组乳腺组织中PRLR的阳性细胞率分别为76.92℅和75.00℅,两组比较无明显的统计学差异(P0.05),且两组间的PRLR阳性的细胞面积、平均光密度值、累积光密度值均无明显的统计学差异(P0.05)。结论:乳房肥大的发生可能与乳腺组织中泌乳素的表达升高有关,而与乳腺组织中泌乳素受体的表达无关。     

羊骨胶原肽对青春期大鼠催乳素和促黄体生成素分泌脉冲的影响

目的研究羊骨胶原肽(sheep bone collagen peptide,SBCP)对类固醇诱导的去卵巢大鼠催乳素(pro-lactin,PRL)和促黄体生成素(luteinizing hormone,LH)分泌脉冲的影响。方法 6周龄子宫颈未开口的青春期SD大鼠实施双侧卵巢摘除手术,康复1周或3周后以类固醇替代方法诱导PRL和LH脉冲,处理组同时按1000 mg/(kg.d)的剂量以SBCP灌胃,通过颈导管采集血样,利用放射免疫技术测定各组大鼠外周血中的LH和PRL浓度。结果对于术后康复1周的大鼠,SBCP对LH脉冲振幅起到增强作用,而对PRL脉冲没有影响;对于术后康复3周的大鼠,SBCP对LH和PRL脉冲振幅均表现为降低作用,但卵巢摘除后立即给予SBCP可减弱这种降低作用。结论雌激素和孕激素替代注射的同时,补充羊骨胶原肽,不仅仍可诱导LH和PRL脉冲的产生,还可预防由于卵巢摘除带来的骨代谢紊乱,免疫力低下等不良影响,因而是对现有类固醇替代方法的改良。     

Cimetidine is critical in CNS disorders

There are many CNS disorders with imbalance of dopamine in brain. Cimetidine adversely increases serum level of the prolactin and leads to activate feedback control to decrease prolactin release and intensifies synthesis and secretion of dopamine. Thus, cimetidine can be critical in CNS disorders.     

Mammary gland zinc metabolism: regulation and dysregulation

Zinc (Zn) is required for numerous metabolic processes serving both a structural and catalytic role. The mammary gland has a unique Zn requirement resulting from the need to also transfer an extraordinary amount of Zn into milk (~0.5–1 mg Zn/day) during lactation. Impairments in this process can result in severe Zn deficiency in the nursing offspring which has adverse consequences with respect to growth and development. Moreover, dysregulated mammary gland Zn metabolism has recently been implicated in breast cancer transition, progression and metastasis, thus there is a critical need to understand the molecular mechanisms which underlie these observations. Tight regulation of Zn transporting mechanisms is critical to providing an extraordinary amount of Zn for secretion into milk as well as maintaining optimal cellular function. Expression of numerous Zn transporters has been detected in mammary gland or cultured breast cells; however, understanding the molecular mechanisms which regulate mammary Zn metabolism as well as the etiology and downstream consequences resulting from their dysregulation is largely not understood. In this review, we will summarize the current understanding of the regulation of mammary gland Zn metabolism and its regulation by reproductive hormones, with a discussion of the dysregulation of this process in breast cancer.     

Extracellular Signal-regulated Kinase 5 (ERK5) Mediates Prolactin-stimulated Adult Neurogenesis in the Subventricular Zone and Olfactory Bulb

Prolactin-stimulated adult neurogenesis in the subventricular zone (SVZ) and olfactory bulb (OB) mediates several reproductive behaviors including mating/pregnancy, dominant male pheromone preference in females, and paternal recognition of offspring. However, downstream signaling mechanisms underlying prolactin-induced adult neurogenesis are completely unknown. We report here for the first time that prolactin activates extracellular signal-regulated kinase 5 (ERK5), a MAP kinase that is specifically expressed in the neurogenic regions of the adult mouse brain. Knockdown of ERK5 by retroviral infection of shRNA attenuates prolactin-stimulated neurogenesis in SVZ-derived adult neural stem/progenitor cells (aNPCs). Inducible erk5 deletion in adult neural stem cells of transgenic mice inhibits neurogenesis in the SVZ and OB following prolactin infusion or mating/pregnancy. These results identify ERK5 as a novel and critical signaling mechanism underlying prolactin-induced adult neurogenesis.     

24-Hour Changes in Circulating Prolactin,Follicle-Stimulating Hormone,Luteinizing Hormone,and Testosterone in Young Male Rats Subjected to Calorie Restriction

This work analyzes the effect of calorie restriction on the 24 h variation of pituitary-testicular function in young male Wistar rats by measuring the circulating levels of prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone. Control animals were provided an equilibrium calorie diet and the experimental animals a calorie-restriction diet equivalent to 66% of food restriction for four weeks starting on day 35 of life. Different groups of control and experimental rats were killed at 6 h intervals around the clock, beginning 1 h after light on (HALO). Compared to the control animals, the mean secretion of prolactin was augmented and that of LH and testosterone decreased in calorie-restricted rats, whereas FSH release remained unchanged. Significant changes in the 24 h secretory pattern of circulating prolactin, LH, and testosterone occurred in the calorie-restricted rats. These include the appearance of a second maximum of plasma prolactin at 21 HALO, blunting of the LH peak seen at 13 HALO, and phase-shift of the testosterone peak from 13 HALO in controls to 17 HALO in calorie-restricted rats. The significant positive correlation between individual LH and testosterone levels found in controls was no longer observed in calorie-restricted rats. Availability of nutrients presumably affects the mechanisms that modulate the circadian variation of the pituitary-gonadal axis in growing male rats.