Effect of ovine prolactin on serum somatomedin bioactivity in hypophysectomized female rats

Heterogeneity analysis of the immune microenvironment in laryngeal carcinoma revealed potential prognostic biomarkers

Laryngeal squamous cell cancer (LSCC) is the second most prevalent malignancy occurring in the head and neck with a high incidence and mortality rate. Immunotherapy has recently become an emerging treatment for cancer. It is therefore essential to explore the role of tumour immunity in laryngeal cancer. Our study first delineated and evaluated the comprehensive immune infiltration landscapes of the tumour microenvironment in LSCC. A hierarchical clustering method was applied to classify the LSCC samples into two groups (high- and low-infiltration groups). We found that individuals with low immune infiltration characteristics had significantly better survival than those in the high-infiltration group, possibly because of the elevated infiltration of immune suppressive cells, such as regulatory T cells and myeloid-derived suppressor cells (MDSCs), in the high-infiltration group. Differentially expressed genes (DEGs) between two groups were involved in some immune-related terms, such as antigen processing and presentation. A univariate Cox analysis and least absolute shrinkage and selection operator (LASSO) analysis were performed to identify an immune gene-set-based prognostic signature (IBPS) to assess the risk of LSCC. The prognostic model comprising six IBPSs was successfully verified to be robust in different cohorts. The expression of the six IBPSs was detected by immunohistochemistry (IHC) in 110 cases of LSCC. In addition, different inflammatory profiles and immune checkpoint landscape of LSCC were found between two groups. Hence, our model could serve as a candidate immunotherapeutic biomarker and potential therapeutic target for laryngeal cancer.

Lack of effect of 10 kV/m 60 Hz electric field exposure on pregnant dairy heifer hormones

Sixteen pregnant Holstein heifers weighing 521 +/- 46 kg, at 3.3 +/- 0.7 months of gestation and 2.2 +/- 2.0 months of age were confined to wooden metabolism cages and were exposed to a vertical electric field (EF) of 10.0 +/- 0.4 kV/m and an artificial light cycle of 12 h light-12 h dark. The heifers were divided into two replicates of eight each. Each replicate was divided into two groups of four animals each, one group becoming the non-exposed and the second, the EF exposed group. The exposed group were housed in metabolism cages in an area where EF were generated, and the non-exposed group, in metabolism cages located in the adjacent area where the EF was less than 2% of that present in the exposed area. The test animals were subject to the different treatments for 4 weeks continuously. After 4 weeks, the animals switched treatment, the exposed group becoming the non-exposed group and vice-versa. Then the treatment continued for 4 more weeks. Catheters were inserted into the jugular vein of the animals, and blood samples were collected on twice a week to estimate the serum concentration of progesterone (P4), melatonin (MLT), prolactin (PRL), and insulin-like growth factor-1 (IGF-1). Feed consumption was measured daily and feed samples were collected twice a week. The results indicated that exposure of dairy cattle to EF similar to those encountered directly underneath a 735 kV high tension electrical power line carrying a maximum load of current, cannot be associated with any variation in the experimental variables mentioned above. An exception to this, is the variation in MLT, which was associated with the EF exposure. Due to the inconsistency of the MLT response in the different replicates, caution should be exercised in the interpretation of this phenomenon.

[Principles and clinical significance of insulin-like growth factors/somatomedins]

The Insulin-like Growth Factors (IGFs) or Somatomedins are polypeptide growth factors which are similar to insulin in respect to their aminoacid sequence, structure and biologic activities. The IGFs bind to high affinity receptors which are present on many cells and in many tissues. In the circulation the IGFs are bound to transport (binding) proteins (IGF-BPs). In this review the physiologic role, the basic chemistry and the gene expression of this family of growth factors is summarized systematically. The pathophysiology of growth disorders, diabetes mellitus, malnutrition, liver and kidney disease in relation to the IGFs as well as the therapeutic and diagnostic potentials of these peptides are discussed in detail.

Growth hormone is secreted by ectopic pituitary grafts and stimulates maternal behavior in rats

The onset of maternal behavior at parturition in rats is hormonally regulated. Recently, we reported that treatment of behaviorally inexperienced, hypophysectomized (hypox), ovariectomized (ovx) rats with a sequential steroid treatment of progesterone (P) and estradiol (E2), and either ectopic anterior pituitary grafts or prolactin (PRL), stimulated maternal responsiveness toward foster young. That growth hormone (GH) has a number of PRL-like activities led us to ask whether the actions of PRL on maternal behavior were specific to PRL or might be shared by other PRL-like protein hormone, i.e., GH. In Experiment 1 we quantified plasma concentrations of GH and PRL by RIA in groups of hypox female rats that were ovariectomized and treated with a combination of ectopic pituitary grafts (Days 1-23) and Silastic capsules filled with P (Days 1-11) and E2 (Days 11-23). Blood samples were collected from Days 1 to 23 of treatment. Both plasma PRL and GH levels increased after grafting, initially rising 10- to 60-fold by Day 4 and gradually declining throughout the remainder of the 23-day sampling period. Throughout the 3-week period after grafting plasma GH levels were as high or higher than those of PRL. In Experiment 2 the behavioral effects of exogenously administered ovine (o)-GH were measured in groups of hypox, ovx rats that were treated with P and E2 as in Experiment 1. Experimental rats were injected twice daily with 0.25 mg oGH beginning on Day 1. Testing for maternal behavior toward foster young was conducted daily from Day 12 to Day 22. In steroid-treated rats, GH treatment stimulated a more rapid onset of maternal behavior (latencies of 3 vs greater than 10 days for vehicle-injected controls). These data indicate that GH, like PRL, is secreted by ectopic pituitary grafts and is capable of stimulating maternal behavior.

Secretion of prolactin-synergizing activity (synlactin) by the liver of ectothermic vertebrates in vitro

Recent work in our laboratory indicated that the liver of rats and pigeons secretes a prolactin synergist (synlactin) in vitro. We have investigated the secretion of this activity by the liver of nine species of ectothermic vertebrates. Liver from three teleosts (goby, salmon, and tilapia), four amphibians (Ambystoma, Necturus, bullfrog, and grass frog) and two reptiles (turtle and anole) was diced, washed, and incubated for 3 hr in isotonic medium. After dialysis, the liver incubation media (LIM) were tested with and without prolactin (PRL) in the local pigeon crop-sac bioassay. The LIM for turtle, larval bullfrog, freshwater salmon, and 5% seawater-adapted goby significantly augmented the local crop-sac response to PRL, but the LIM from anole, adult bullfrog, grass frog, fasted larval Ambystoma, Necturus, 100% seawater-adapted goby, and tilapia did not contain synergizing activity. We conclude that synlactin is secreted by the liver of several species representing three of the major ectothermic classes of vertebrates. It is significant that in two cases, larval bullfrog and 5% seawater-adapted goby, the presence of synlactin occurs in physiological states in which PRL is active. In the opposite cases (adult frog and 100% seawater-adapted goby) the activity was not detectable. We also found that the liver of larval and adult bullfrogs and tilapia released a factor in vitro that had proliferative activity in the crop-sac. This activity appears to be distinct from synlactin.

Prolactin's mitogenic action on the pigeon crop-sac mucosal epithelium involves direct and indirect mechanisms

It has long been known that prolactin (PRL) induces proliferation of the mucosal epithelial lining of the pigeon crop-sac. This system was used to study possible interactions of other hormones with PRL's mitogenic effect directly on the crop-sac cells. Injection of a sheep pituitary powder into the loose skin between the leg and abdomen of pigeons increased the responsiveness of the crop-sac to direct, local application of PRL. Similar systemic injections of anterior pituitary hormones, ACTH and TSH (alone or together), or a combination of LH and FSH, were without effect on the local response to PRL. However, systemically injected PRL and GH resulted in a dramatic augmentation of the response of the organ to local injection of PRL. PRL was more potent than GH in this regard. These results suggest that PRL has at least two modes of action as a mitogen on this epithelium--its well-known direct action on the cells and an indirect action as well that is possibly mediated by the secretion of another factor into the blood stream. Because it was previously found that somatomedin-like molecules, including proinsulin, act synergistically with PRL to promote proliferation of these cells when coinjected locally with PRL (T. R. Anderson, J. Rodriguez , D. S. Pitts , E. M. Spencer, and C. S. Nicoll , 1983, In "Insulin-like Growth Factors/Somatomedins," de Gruyter , Berlin), The effects of systemic injections of proinsulin were also tested. Proinsulin had a potentiating effect similar to that of the pituitary powder and of GH or PRL. These results are consistent with the following interpretations: When PRL promotes crop-sac proliferation to produce crop-milk in pigeons and doves, the hormone acts through at least two mechanisms. One of these is a direct effect on the crop-sac, which sensitizes the mucosal epithelium to the mitogenic action of a somatomedin-like growth factor. The second effect is an increase in the production and/or secretion of the factor, which then acts synergistically with PRL to promote proliferation of the crop-sac mucosal cells. More direct evidence for this proposal was provided by the finding that serum from saline- or PRL-treated pigeons did not stimulate crop-sac mucosal growth when it was injected locally. However, the serum from PRL-treated birds had a much higher level of an activity that augmented the effects of PRL when the sera were locally injected in combination with PRL.(ABSTRACT TRUNCATED AT 400 WORDS)

Insulin and insulin-like growth factors/somatomedins in fetal and neonatal development

In this presentation we have attempted to review the status of knowledge of the hormonal regulation of fetal and neonatal growth, and have placed particular emphasis on the roles of insulin and somatomedin in fetal growth. The inaccessibility of the fetus and the physical and ethical constraints on study of its growth have resulted in slow progress. Furthermore, the opportunity for the fetus to benefit from homologous hormones from a variety of sources has made it difficult to assess the effect of withdrawal of individual hormones. Many of the advances made have resulted from attempts to determine hormone concentrations in fetal blood, identify hormone binding by fetal tissues, and examine the effects of natural or experimentally induced deviations in hormone availability. In the future, attention should be focused on developing study models which better isolate the fetus from the influence of multiple, homologous hormones. Progress should also come as the result of more detailed study of the influence of individual growth factors on in vitro growth of fetal cells and tissues, assessment of control mechanisms for growth factors in the fetus, and experiments directed at recognizing the complex interactions between individual growth factors and between growth factors and hormones.

Insulin-like growth factors I and II, prolactin, and insulin in 19 growth hormone-deficient children with excessive, normal, or decreased longitudinal growth after operation for craniopharyngioma

We studied insulin-like growth factors (IGF) I and II, prolactin, and the insulin response to arginine in 19 children with craniopharyngioma and documented growth hormone deficiency. Patients were divided into three groups according to their growth rate during the first postoperative year. Seven patients with excessive growth (Group A) had hyperinsulinism, normal IGF values, elevated basal prolactin levels, and a delayed thyrotropin response to thyrotropin-releasing hormone, which was compatible with hypothalamic lesions. In the six patients with normal growth (Group B), the insulin level was low; all other hormone values were similar to those of Group A. In the six patients with decreased growth (Group C), levels of IGF I, insulin, prolactin, and thyrotropin were low, indicating the presence of severe pituitary damage and explaining the failure to grow. Patients in all groups had low or undetectable basal levels of growth hormone. We conclude that in Group B, normal IGF permitted normal growth, and prolactin hypersecretion may have been responsible for normal IGF I values. Excessive growth in Group A may have been caused by hyperinsulinism associated with hyperphagia and obesity of hypothalamic origin.

The effect of fasting on liver receptors for prolactin and growth hormone

The effects of 3 day fasting on liver prolactin and growth hormone receptors have been investigated in male and female rats. Fasting caused a significant fall in serum immunoreactive insulin (67% decrease), while receptor-reactive somatomedin fell 82% when measured in whole serum and by 72% when measured in serum fractions following gel chromatography at low pH. Tracer ovine prolactin binding to liver microsomal membranes was reduced by 55% on fasting in females, but unchanged in males. Tracer bovine growth hormone binding fell significantly in both sexes. Analysis of competitive binding curves showed the decrease binding to be due to a loss of prolactin receptors in females, and of high affinity (but not low affinity) growth hormone receptors in males and females. Significant correlations were seen between serum insulin and tracer prolactin (females) and growth hormone (males and females) binding to liver membranes. Correlations between serum insulin and liver high affinity growth hormone binding sites were particularly significant (r = 0.899 in females, r = 0.910 in males). It is proposed that the hypoinsulinemia of fasting causes a loss of high affinity growth hormone receptors in the liver, which could result in a relative hepatic resistance to growth hormone and a decreased hepatic generation of somatomedin.