Prolactin Levels in Workers Exposed to Chemical, Physical and Psycho‐Social Urban Stressors

Hypothalamus and Post-Traumatic Stress Disorder: A Review

Humans have lived in a dynamic environment fraught with potential dangers for thousands of years. While fear and stress were crucial for the survival of our ancestors, today, they are mostly considered harmful factors, threatening both our physical and mental health. Trauma is a highly stressful, often life-threatening event or a series of events, such as sexual assault, war, natural disasters, burns, and car accidents. Trauma can cause pathological metaplasticity, leading to long-lasting behavioral changes and impairing an individual's ability to cope with future challenges. If an individual is vulnerable, a tremendously traumatic event may result in post-traumatic stress disorder (PTSD). The hypothalamus is critical in initiating hormonal responses to stressful stimuli via the hypothalamic-pituitary-adrenal (HPA) axis. Linked to the prefrontal cortex and limbic structures, especially the amygdala and hippocampus, the hypothalamus acts as a central hub, integrating physiological aspects of the stress response. Consequently, the hypothalamic functions have been attributed to the pathophysiology of PTSD. However, apart from the well-known role of the HPA axis, the hypothalamus may also play different roles in the development of PTSD through other pathways, including the hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-gonadal (HPG) axes, as well as by secreting growth hormone, prolactin, dopamine, and oxytocin. This review aims to summarize the current evidence regarding the neuroendocrine functions of the hypothalamus, which are correlated with the development of PTSD. A better understanding of the role of the hypothalamus in PTSD could help develop better treatments for this debilitating condition.

No Correlation between Blood Benzene Levels and Luteinizing Hormone Plasma Values in Outdoor Workers

OBJECTIVE

The purpose of the study is to evaluate whether low-dose exposure to benzene, an environmental pollutant to which male and female traffic policemen are daily exposed to could cause alterations in plasma luteinizing hormone (LH) levels.

METHODS

From an initial sample of 1594 workers, we only selected 95 workers of whom study we knew the values of late-shift benzene and LH hormone. All subjects underwent biological monitoring (final blood benzene evaluation) and luteinizing hormone dosing. Excluding subjects with the main confounding factors, the final sample included 76 workers. The normal distribution of the variables was evaluated using the Kolmogorov - Smirnov test, followed by the logarithmic transformation of the LH and benzene values. The comparison among means was performed by using the t-test for the independent samples. The ANOVA test was performed for variables with more than 2 modes (ages and seniority) and Pearson correlation index between variables in the total sample and after subdivision as to sex, job, sports activity and smoking. The results were considered significant when p values were less than 0.05.

RESULTS/CONCLUSION

The study did not show a correlation between benzene levels and LH plasma levels in outdoor workers.

Elevated serum prolactin levels as a marker of inflammatory arthritis in psoriasis vulgaris

BACKGROUND AND AIMS

Psoriasis vulgaris (PV) is complicated in up to 40% patients by the inflammatory joint disease psoriatic arthritis (PsA). Neither the aetiology of the arthritis nor specific laboratory markers for its disease activity have been clearly elucidated. Prolactin (PRL) acts as a cytokine with immunomodulatory functions and plays a role in skin and joint biology. The results on PRL however as a marker are unclear. The aim of this study was to confirm whether serum PRL levels reflect systemic complications of PV, like inflammatory joint disease and/or can serve as a marker of disease activity in both cases.

METHODS

A total of 70 patients with PV without arthritis and 40 patients suffering from PsA were included. In all patients, we determined skin disease activity according to the PASI index and in PsA, active disease assessed as swollen or tender joints. The control group included 27 age and sex matched healthy individuals. The concentration of PRL in the serum was measured by immunoradiometric assays.

RESULTS

The PRL serum levels were significantly increased in PsA patients (299.2±28.29 mIU/L) compared to PV only patients (201.4.2±11.72 mIU/L), P = 0.0003 and healthy individuals (198.2±15.31 mIU/L), P = 0.007. The serum PRL levels in PsA with active disease 336.8±42.50 (mIU/L) were higher than in PV and controls, P < 0.0001 and P = 0.002 respectively. In PV only patients, there was no correlation between PASI and PRL levels.

CONCLUSION

Our results showed that PRL serum levels are a marker of active arthritis in PsA and reflects systemic complication rather than local skin activity.

Urinary nickel and prolactin in workers exposed to urban stressors

The aim of our study is to verify whether the exposure to low Ni doses in urban air may have some effects on the prolactin values of outdoor workers exposed to urban pollutants. 334 workers have been included in the study and divided on the basis of gender, job, age, length of service and smoking habits. Each worker underwent urinary Ni and prolactin sampling. The t-test for independent samples, the Mann-Whitney U test for two mode variables (gender, smoking habit), the univariate ANOVA test and the Kruskal Wallis test for the variables in more than two modes (age, length of service and job duties) were performed on the total sample. Pearson's correlation coefficient (p two-tailed) among the parameters was evaluated both in the total sample and after the stratification by gender, smoking habit and job. Multiple linear regression was performed after taking account of the major confounding factors on the total sample and on the subcategories. The statistical tests showed a significant correlation between urinary Ni and prolactin both in the total sample and in the subcategories. We believe that the occupational exposure to low doses of Ni present in urban pollution may influence the prolactin values in exposed workers.

Professional exposure to urban stressors and effects on urinary metanephrines

The aim of the study is to assess whether occupational exposure to urban stressors could cause alterations in urinary metanephrines levels in traffic policemen vs administrative staff of municipal police. A total of 258 subjects were included in the study: 129 traffic policemen exposed to urban stressors (68 males and 61 females) and 129 controls (68 males and 61 females). Urinary metanephrines mean levels were significantly higher in male traffic policemen compared to controls (p < 0.01). No significant differences were in female traffic policemen compared to controls. In the control group, urinary metanephrines mean levels were significantly higher in females compared to males (p < 0.01). There were no significant differences in urinary metanephrines mean levels in female traffic policemen vs male traffic policemen. The increase in urinary metanephrines mean levels observed in male exposed compared to controls could be related to chronic occupational exposure to low doses of chemical, physical and psychosocial urban stressors.

Follicle-stimulating hormone levels in male workers exposed to urban chemical, physical, and psychosocial stressors

The aim of this study is to evaluate whether occupational exposure to urban stressors could cause alterations in the follicle-stimulating hormone (FSH) levels in traffic policemen compared to a control group. After excluding the subjects with main confounding factors, traffic policemen and male controls were matched by age, working life, body mass index (BMI), drinking habit, cigarette smoking history, and daily consumption of Italian coffee, 166 traffic policemen and 166 controls were included into the study. FSH levels were significantly higher in traffic policemen compared to male controls ( P < 0.05). The distribution of FSH values in traffic policemen and controls was significant ( P < 0.05). Our results suggest that occupational exposure to low doses of chemical and psychosocial stressors may alter plasma levels of FSH in traffic policemen more than in the control group. If the results obtained are confirmed by further research, the plasma levels of FSH may be used as early biological markers, valuable for the group, used in occupational set even before the appearance of disorders of male fertility.

Luteinizing hormone (LH) levels in male workers exposed to urban stressors

The aim of the study is to evaluate if occupational exposure to urban stressors could cause alterations in luteinizing hormone (LH) plasma levels in male traffic policemen vs. administrative staff of Municipal Police.After excluding the subjects with the main confounding factors, male traffic police and administrative staff of Municipal Police were matched by age, working life, body mass index (BMI), alcohol drinking habit, cigarette smoking habit and habitual consumption of Italian coffee.In 166 male traffic police mean LH values were significantly higher compared to 166 male administrative employees. The distribution of LH values in traffic police and in administrative employees was statistically significant.Our results suggest that recent exposure to urban stressors (chemical, physical and psycho-social) can alter the plasma concentration of LH. In agreement with our previous research, levels of plasma LH may be used as early biological markers, valuable for the group, used in occupational set before the appearance of the disease.

GABAergic mediation of stress-induced secretion of corticosterone and oxytocin, but not prolactin, by the hypothalamic paraventricular nucleus

The hypothalamus-pituitary-adrenal axis (HPA) participates in mediating the response to stressful stimuli. Within the HPA, neurons in the medial parvocellular region of paraventricular nucleus (PVN) of the hypothalamus integrate excitatory and inhibitory signals triggering secretion of corticotropin-releasing hormone (CRH), the main secretagogue of adrenocorticotropic hormone (ACTH). Stressful situations alter CRH secretion as well as other hormones, including prolactin and oxytocin. Most inputs to the PVN are of local origin, half of which are GABAergic neurons, and both GABA-A and GABA-B receptors are present in the PVN. The objective of the present study was to investigate the role of GABA-A and GABA-B receptors in the PVN's control of stress-induced corticosterone, oxytocin and prolactin secretion. Rats were microinjected with saline or different doses (0.5, 5 and 50 pmol) of GABA-A (bicuculine) or GABA-B (phaclofen) antagonists in the PVN. Ten minutes later, they were subjected to a stressor (ether inhalation) and blood samples were collected 30 min before and 10, 30, 60, 90 and 120 min after the stressful stimulus to measure hormone levels by radioimmunoassay. Our results indicate that GABA acts in the PVN to inhibit stress-induced corticosterone secretion via both its receptor subtypes, especially GABA-B. In contrast, GABA in the PVN stimulates oxytocin secretion through GABA-B receptors and does not alter prolactin secretion.

Increased serum cortisol and growth hormone levels in earthquake survivors with PTSD or subclinical PTSD

Alteration of neuroendocrine systems has been demonstrated to be involved in the pathology of posttraumatic stress disorder (PTSD). Three months after an earthquake in Northern China, cortisol, growth hormone (GH) and prolactin (PRL) levels were assessed in 34 earthquake survivors with PTSD (according to DSM-IV criteria), 30 earthquake survivors with subclinical PTSD and 34 normal controls. Only earthquake survivors diagnosed with PTSD had significantly higher serum GH levels. Also, we found that earthquake survivors (either with PTSD or subclinical PTSD) had significantly higher serum cortisol levels. We concluded that PTSD might be associated with an increased level of serum GH and traumatic survivors might be associated with a higher level of serum cortisol.

Stress hormones and immune function

Over the past 20 years we have demonstrated both in animal models and in human studies that stress increases neuroendocrine hormones, particularly glucocorticoids and catecholamines but to some extent also prolactin, growth hormone and nerve growth factor. We have also shown that stress, through the action of these stress hormones, has detrimental effects on immune function, including reduced NK cell activity, lymphocyte populations, lymphocyte proliferation, antibody production and reactivation of latent viral infections. Such effects on the immune system have severe consequences on health which include, but are not limited to, delayed wound healing, impaired responses to vaccination and development and progression of cancer. These data provide scientific evidence of the effects of stress on immune function and implications for health.