Prolactin in ovarian follicular fluid stimulates endothelial cell proliferation.

Angiogenesis is essential for the growth and maturation of the ovarian follicle and its transition into the corpus luteum. In addition to the main proangiogenic factors, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), follicular fluid (FF) contains the hormone prolactin (PRL), which is known to promote angiogenesis in vivo. Here, we show that FF from large follicles, which contains twice the PRL level of FF from small follicles, stimulates endothelial cell proliferation to a greater extent than the latter, and that immunoneutralization of PRL prevents FF from stimulating endothelial cell proliferation. Notably, the FF increases the expression of the short and long PRL receptor isoforms in endothelial cells, and a purified PRL standard stimulates endothelial cell proliferation but only after the cells have been pretreated with FF. However, purified PRL activates the JAK2/STAT3 pathway in endothelial cells in the absence of pretreatment with FF. In summary, PRL present in the FF stimulates the proliferation of endothelial cells. This effect likely involves the upregulation of the short and long PRL receptor isoforms and is independent of PRL-induced JAK2/STAT3 signaling.

Prolactin released in vitro from the pituitary of lactating, pregnant, and steroid-treated female or male rats stimulates prolactin secretion from pituitary lactotropes of male rats.

We have previously shown that soluble factor(s) in conditioned media (CM) from the central and peripheral regions of the anterior pituitary (AP) gland of lactating rats promoted the in vitro dose-related release of prolactin (PRL) from pituitary glands of male rats. In the present experiments we sought to determine whether CM from rats in different physiological states provoked similar effects (like those of lactating rats), and the nature of the factors, whether 23K PRL or other variants of the hormone, were responsible for these effects. Stimulatory effects were induced by CM from pregnant females and steroid-treated castrated males or females, but not from untreated castrated rats, intact males, or by a PRL standard. More potent effects occurred with CM from APs of early- than from mid- or late-lactating rats, and from rats unsuckled for 8 or 16 h than from those unsuckled for 32 h. With respect to the nature of factor(s) responsible for these effects, immunoprecipitation of PRL from the CM of lactating females and of steroid-treated, castrated males eliminated, whereas dephosphorylation or deglycosylation of CM of lactating rats greatly increased its effects upon PRL release. Also, electrophoretic analysis and Western blotting of the CM proteins under native and denaturing conditions revealed a variety of PRL variants, ranging from 14 to <90 kDa, in CM from lactating rats, and the main effects on PRL release were provoked by the 23- to 46-kDa PRL variants. These results indicate that specific effects upon male rat lactotropes may be exerted by PRL variants released from APs of lactating and non-lactating rats.

Smoking index, lifestyle factors, and genomic instability assessed by single-cell gel electrophoresis: a cross-sectional study in subjects from Yucatan, Mexico.

BACKGROUND: It is widely accepted that genomic instability is associated with several mechanisms involving oxidative stress, which can increase the rate of DNA breaks. Such factors include smoking, impairments in body composition, an unhealthy lifestyle, and a hereditary history of cancer. The aim was to evaluate the degree of association of genomic instability in smokers and non-smokers, and how the risk could change depending on the lifestyle and other causes. For this purpose, a survey of tobacco consumption, dietary patterns, physical activity, antecedents of cancer, and body composition assessment was carried out. Genomic instability was evaluated through a single-cell gel electrophoresis using peripheral blood mononuclear cells in three different conditions of oxidative stress. The analysis of genomic damage degree was performed through a dimension reduction procedure (principal component analysis) from 16 parameters per treatment (adding up 48 parameters of genomic damage per subject) and a binary logistic regression model for DNA fragmentation risk. RESULTS: The sample consisted of 82 participants, divided into three age groups: young adults (18-35 years), adults (36-59 years), and older adults (60-95 years). As expected, the results showed a significant positive correlation of age with genomic damage rates, represented by 2 PCA groups (p = 0.027, p = 0.004). There were consistent significant positive associations of genomic damage rates with smoking index and three PCA groups (p = 0.007, p = 0.004, p = 0.009). The smoking status and age group analysis revealed that there were significant differences for adult smokers with the same aforementioned PCA groups (p = 0.002, p = 0.001, p = 0.010). In addition, higher DNA damage rates were found in subjects with incorrect diet patterns, long sitting hours, and previous exposure to radiation. The analysis with binary logistic regression displayed two models in which lifestyles (age, diet, and/or sedentarism) did not change the significance of smoking index for DNA fragmentation risk; however, when physical activity was present in the model, the smoking index was not a significant factor for DNA damage risk. CONCLUSIONS: Although it is well known that smoking affects human health in different ways, DNA fragmentation can be analyzed by a damage phenotypic analysis and integrate a risk analysis reshaped by diet and lifestyle in general.

Suckling-induced oxytocin increase in the spinal cord of the rat.

Oxytocin (OT) is essential for parturition and milk ejection, and OT-containing fibers are present in several regions of the brain and in the spinal cord. During lactation, activation of spinal cord neurons by suckling stimulation involves deep laminae III-X including sympathetic preganglionic neurons of the intermedio-medial cell column. In the present study, experiments were designed to determine if the suckling provided by the litter increased OT levels in the spinal cord of dams, as determined by competitive immunoassay. In addition, we investigated if OT fibers reach neurons of the spinal cord that are known to respond to suckling. The OT content was higher in the hypothalamus than in the spinal cord in animals from all experimental groups. After 6 h of pup separation, OT levels decreased and suckling for 5 min induced a significant increase of OT levels in the spinal cord. Double immunostaining for Fos and OT showed OT-positive fibers adjacent to neurons that had Fos-positive nuclei, located mostly in laminae III, IV, and X. The present data support the notion that OT is released within the spinal cord in response to suckling, suggesting a role for this peptide in modulating the afferent and/or efferent responses generated by suckling.

Vesicular release of prolactin from preformed prolactin granules is stimulated by soluble factor(s) from the anterior pituitary of lactating rats.

This study demonstrates that conditioned media (CM) from the anterior pituitary gland (AP) of lactating rats contains soluble factors that promote in vitro prolactin (PRL) release from the pituitary glands of male rats. CM-induced PRL release was confirmed by polyacrylamide gel electrophoresis, ELISA and bioassay. In cultured AP cells challenged with CM, increased intracellular staining with the dye FM1-43 was observed, suggesting vesicular PRL release and subsequent endocytosis. The percentage and hormone content of PRL-containing cells but not of growth hormone-containing cells increased in cultured male AP cells when exposed to CM. When the release of PRL, prelabeled with [3H] leucine for 30 min to 24 h was examined, no stimulatory effect of CM was observed, suggesting that released PRL originates from hormone synthesized more than 24 h earlier. Accordingly, the PRL content of mature granules from male pituitary tissues decreased after CM treatment. These findings were confirmed by electron microscopy immunogold PRL labeling. Treatment with inhibitors of protein synthesis or vesicle trafficking between the endoplasmic reticulum and the Golgi complex did not prevent the stimulatory effect of CM on PRL release. However, blockage of traffic to the plasma membrane completely abolished the effect of CM. These results suggest that CM from the AP of lactators contains soluble factor(s) capable of inducing rapid vesicular release of PRL in the male AP, which originates from preformed, mature granules by mechanisms independent of protein synthesis.