Maternal separation on the ethanol-preferring adult rat liver structure

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Activity of neurons in the preoptic area and their participation in reproductive senescence: preliminary findings

Alterations in the hypothalamic-pituitary-gonadal axis in females determine the transition from regular to irregular reproductive cycles, with loss of fertility. Stimulation of noradrenergic neurons of the anteroventral periventricular neurons (AVPV) is essential for regular reproductive cycles. Therefore, we examined the activity of neurons of the AVPV and measure the noradrenaline (NE) of acyclic rats, in constant estrus, and compared it with that of cyclic rats in estrus. Female cyclic (4-5months) and acyclic (17-18months) rats were euthanized at 10, 14, and 18h in estrus. Brains were processed for immunoreactivity to antigens related to Fos (FRA) in AVPV, and the NE was determined by HPLC-ED. Plasma concentrations of LH, FSH, E2 and P4 were determined. In the acyclic animals, plasma LH was higher but the FSH was lower. There was decreasing P4 at different times, while the E2 was constant and lower in acyclic rats. FRA-ir expression in AVPV neurons of acyclic rats as well as turnover of NE was higher when compared with cyclic group. The preliminary findings showed increased activity in AVPV neurons in aging contribute to changes in the temporal pattern of neuroendocrine signaling, compromising the accuracy of inhibitory and stimulatory effects, causing irregularity in the estrous cycle and determining reproductive senescence.

Atividade dos neurônios do núcleo anterovental periventricular e sua participação no envelhecimento reprodutivo de ratas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Divergent Roles of the CRH Receptors in the Control of Gonadotropin Secretion Induced by Acute Restraint Stress at Proestrus

CRH has been implicated as a mediator of stress-induced effects on the hypothalamus-pituitary-gonad axis, acting via CRH receptors in various brain regions. We investigated whether the effects of restraint stress on the secretion of gonadotropins on the morning of proestrus are mediated by the CRH-R1 or CRH-R2 receptors in the oval subdivision of the anterolateral BST, the central amygdala, the locus coeruleus (LC), or the A1 and A2 neuron groups in the medulla. At proestrus morning, rats were injected with antalarmin (a CRH-R1 antagonist), asstressin2-B (a CRH-R2 antagonist) or vehicles. Thirty minutes after the injection, the animals were placed into restraints for 30 min, and blood was sampled for 2 h. At the end of the experiment, the brains were removed for immunofluorescence analyses. Restraint stress increased the levels of FSH and LH. Antalarmin blocked the stress-induced increases in FSH and LH secretion, but astressin2-B only blocked the increase in FSH secretion. LC showed intense stress-induced neuronal activity. FOS/tyrosine-hydroxylase coexpression in LC was reduced by antalarmin, but not astressin2-B. The CRH-R1 receptor, more than CRH-R2 receptor, appears to be essential for the stimulation of the hypothalamus-pituitary-gonad axis by acute stress; this response is likely mediated in part by noradrenergic neurons in the LC. We postulate that the stress-induced facilitation of reproductive function is mediated, at least in part, by CRH action through CRH-R1 on noradrenaline neurons residing in the LC that trigger GnRH discharge and gonadotropin secretion. (Endocrinology 153: 4838-4848, 2012)

Oxytocin interference in the effects induced by inhalation of 7.5% CO2 in healthy volunteers

Objective The objective of this study was to assess the acute effect of intranasally administered oxytocin (OT) on subjective states, cardiovascular, and endocrine parameters in healthy volunteers who inhaled 7.5% CO2. Methods Forty-five subjects were allocated into three matched groups of subjects who received 24?international units (IU) of OT, 2?mg of lorazepam (LZP), or placebo (PL). The challenge consisted of medical air inhalation for 20?min, 10?min of rest, and CO2 7.5% inhalation for 20?min. Subjective effects were evaluated by self-assessment scales; heart rate, blood pressure, skin conductance, and salivary cortisol were also measured. Assessments were performed at four time points: (i) baseline (-15?min); (ii) post-air inhalation (90?min); (iii) post-CO2 inhalation (120?min), and (iv) post-test (160?min). Results CO2 inhalation significantly increased the anxiety score in the PL group compared with the post-air measurement but not in the OT or LZP groups. The LZP reduced anxiety after medical air inhalation. Other parameters evaluated were not affected by OT. Conclusion OT, as well as LZP, prevented CO2-induced anxiety, suggesting that this hormone has anxiolytic properties. Copyright (C) 2012 John Wiley & Sons, Ltd.

Plasma cortisol in first episode drug-naive mania: Differential levels in euphoric versus irritable mood

Background: Dysregulation of HPA axis has been widely described in subjects with bipolar disorder (BD), including changes in cortisol levels during mood episodes and euthymia. However, most of the studies were done with medicated BD patients with variable length of illness, which was shown to interfere on peripheral cortisol levels. Therefore, the present study aims to evaluate plasma cortisol levels in drug-naive BD subjects during the first manic episode, as well as investigate the relationship between plasma cortisol levels and manic symptomatology. Methods: Twenty-six drug-naive patients were enrolled meeting criteria for a first manic episode in bipolar I disorder. Severity of mania was assessed using the Young Mania Rating Scale (YMRS). The control group included 27 healthy subjects matched by age and gender. Cortisol was quantified using a direct radioimmunoassay. Results: Plasma cortisol levels were decreased during first manic episode compared to healthy controls. Higher cortisol levels were positively associated with the presence of irritability (dysphoria), while elated mania showed lower cortisol levels compared to controls. Limitation: Data including larger samples are lacking. Conclusion: Higher cortisol in dysphoric mania compared to predominantly elated/euphoric mania may indicate a clinical and neurobiological polymorphic phenomenon, potentially involving a higher biological sensitivity to stress in the presence of irritable mood. The present findings highlight the importance to add a dimensional approach to the traditional categorical diagnosis for future neurobiological studies in BD. (C) 2011 Elsevier B.V. All rights reserved.

Anxiolytic-like effect of oxytocin in the simulated public speaking test

Oxytocin (OT) is known to be involved in anxiety, as well as cardiovascular and hormonal regulation. The objective of this study was to assess the acute effect of intranasally administered OT on subjective states, as well as cardiovascular and endocrine parameters, in healthy volunteers (n = 14) performing a simulated public speaking test. OT or placebo was administered intranasally 50 min before the test. Assessments were made across time during the experimental session: (1) baseline (-30 min); (2) pre-test (-15 min); (3) anticipation of the speech (50 min); (4) during the speech (1:03 h), post-test time 1 (1:26 h), and post-test time 2 (1:46 h). Subjective states were evaluated by self-assessment scales. Cortisol serum and plasma adrenocorticotropic hormone (ACTH) were measured. Additionally, heart rate, blood pressure, skin conductance, and the number of spontaneous fluctuations in skin conductance were measured. Compared with placebo, OT reduced the Visual Analogue Mood Scale (VAMS) anxiety index during the pre-test phase only, while increasing sedation at the pre-test, anticipation, and speech phases. OT also lowered the skin conductance level at the pre-test, anticipation, speech, and post-test 2 phases. Other parameters evaluated were not significantly affected by OT. The present results show that OT reduces anticipatory anxiety, but does not affect public speaking fear, suggesting that this hormone has anxiolytic properties.

Chronic Stress Improves the Myocardial Function without Altering L-type Ca+2 Channel Activity in Rats

Background: Chronic stress is associated with cardiac remodeling; however the mechanisms have yet to be clarified. Objective: The purpose of this study was test the hypothesis that chronic stress promotes cardiac dysfunction associated to L-type calcium Ca2+ channel activity depression. Methods: Thirty-day-old male Wistar rats (70 - 100 g) were distributed into two groups: control (C) and chronic stress (St). The stress was consistently maintained at immobilization during 15 weeks, 5 times per week, 1h per day. The cardiac function was evaluated by left ventricular performance through echocardiography and by ventricular isolated papillary muscle. The myocardial papillary muscle activity was assessed at baseline conditions and with inotropic maneuvers such as: post-rest contraction and increases in extracellular Ca2+ concentration, in presence or absence of specific blockers L-type calcium channels. Results: The stress was characterized for adrenal glands hypertrophy, increase of systemic corticosterone level and arterial hypertension. The chronic stress provided left ventricular hypertrophy. The left ventricular and baseline myocardial function did not change with chronic stress. However, it improved the response of the papillary muscle in relation to positive inotropic stimulation. This function improvement was not associated with the L-type Ca2+ channel. Conclusion: Chronic stress produced cardiac hypertrophy; however, in the study of papillary muscle, the positive inotropic maneuvers potentiated cardiac function in stressed rats, without involvement of L-type Ca2+ channel. Thus, the responsible mechanisms remain unclear with respect to Ca2+ influx alterations. (Arq Bras Cardiol 2012;99(4):907-914)

3,4-Methylenedioxymethamphetamine (Ecstasy) Decreases Inflammation and Airway Reactivity in a Murine Model of Asthma

Objective:3,4-Methylenedioxymethamphetamine(MDMA), or ecstasy, is a synthetic drug used recreationally, mainly by young people. It has been suggested that MDMA has a Th cell skewing effect, in which Th1 cell activity is suppressed and Th2 cell activity is increased. Experimental allergic airway inflammation in ovalbumin (OVA)-sensitized rodents is a useful model to study Th2 response; therefore, based on the Th2 skewing effect of MDMA, we studied MDMA in a model of allergic lung inflammation in OVA-sensitized mice. Methods: We evaluated cell trafficking in the bronchoalveolar lavage fluid, blood and bone marrow; cytokine production; L-selectin expression and lung histology. We also investigated the effects of MDMA on tracheal reactivity in vitro and mast cell degranulation. Results: We found that MDMA given prior to OVA challenge in OVA-sensitized mice decreased leukocyte migration into the lung, as revealed by a lower cell count in the bronchoalveolar lavage fluid and lung histologic analysis. We also showed that MDMA decreased expression of both Th2-like cytokines (IL-4, IL-5 and IL-10) and adhesion molecules (L-selectin). Moreover, we showed that the hypothalamus-pituitary-adrenal axis is partially involved in the MDMA-induced reduction in leukocyte migration into the lung. Finally, we showed that MDMA decreased tracheal reactivity to methacholine as well as mast cell degranulation in situ. Conclusions:Thus, we report here that MDMA given prior to OVA challenge in OVA-sensitized allergic mice is able to decrease lung inflammation and airway reactivity and that hypothalamus-pituitary-adrenal axis activation is partially involved. Together, the data strongly suggest an involvement of a neuroinnmune mechanism in the effects of MDMA on lung inflammatory response and cell recruitment to the lungs of allergic animals. Copyright (C) 2012 S. Karger AG, Basel

Effects of Repeated Stress on Distal Airway Inflammation, Remodeling and Mechanics in an Animal Model of Chronic Airway Inflammation

Background/Aims: Epidemiological studies suggest that stress has an impact on asthmatic exacerbations. We evaluated if repeated stress, induced by forced swimming, modulates lung mechanics, distal airway inflammation and extracellular matrix remodeling in guinea pigs with chronic allergic inflammation. Methods: Guinea pigs were submitted to 7 ovalbumin or saline aerosols (1-5 mg/ml during 4 weeks; OVA and SAL groups). Twenty-four hours after the 4th inhalation, guinea pigs were submitted to the stress protocol 5 times a week during 2 weeks (SAL-S and OVA-S groups). Seventy-two hours after the 7th inhalation, guinea pigs were anesthetized and mechanically ventilated. Resistance and elastance of the respiratory system were obtained at baseline and after ovalbumin challenge. Lungs were removed, and inflammatory and extracellular matrix remodeling of distal airways was assessed by morphometry. Adrenals were removed and weighed. Results: The relative adrenal weight was greater in stressed guinea pigs compared to non-stressed animals (p < 0.001). Repeated stress increased the percent elastance of the respiratory system after antigen challenge and eosinophils and lymphocytes in the OVA-S compared to the OVA group (p < 0.001, p = 0.003 and p < 0.001). Neither collagen nor elastic fiber contents were modified by stress in sensitized animals. Conclusions: In this animal model, repeated stress amplified bronchoconstriction and inflammatory response in distal airways without interfering with extracellular matrix remodeling. Copyright (C) 2011 S. Karger AG, Basel

Heat stress impairs performance and induces intestinal inflammation in broiler chickens infected with Salmonella Enteritidis

Stressful situations reduce the welfare, production indices and immune status of chickens. Salmonella spp. are a major zoonotic pathogens that annually cause over 1 billion infections worldwide. We therefore designed the current experiment to analyse the effects of 31 +/- 1 degrees C heat stress (HS) (from 35 to 41 days) on performance parameters, Salmonella invasion and small intestine integrity in broiler chickens infected with Salmonella Enteritidis. We observed that HS decreased body weight gain and feed intake. However, feed conversion was only increased when HS was combined with Salmonella Enteritidis infection. In addition, we observed an increase in serum corticosterone levels in all of the birds that were subjected to HS, showing a hypothalamus-pituitary-adrenal axis activation. Furthermore, mild acute multifocal lymphoplasmacytic enteritis, characterized by foci of heterophil infiltration in the duodenum, jejunum and ileum, was observed in the HS group. In contrast, similar but more evident enteritis was noted in the heat-stressed and Salmonella-infected group. In this group, moderate enteritis was observed in all parts of the small intestine. Lastly, we observed an increase in Salmonella counts in the spleens of the stressed and Salmonella-infected chickens. The combination of HS and Salmonella Enteritidis infection may therefore disrupt the intestinal barrier, which would allow pathogenic bacteria to migrate through the intestinal mucosa to the spleen and generate an inflammatory infiltrate in the gut, decreasing performance parameters.

Changes in prolactin secretion in the short- and long-term after adrenalectomy

OBJECTIVE: To evaluate the modulation of the hypothalamus-pituitary-adrenal axis (HPA) on prolactin secretion in rats after adrenalectomy (ADX). MATERIALS AND METHODS: Plasma corticosterone, ACTH, and prolactin concentrations were measured by radioimmunoassay in rats after bilateral ADX in the short- (3 hours and 1day) and long-term (3, 7, and 14 days). RESULTS: Animals that underwent ADX showed undetectable corticosterone levels and a triphasic ACTH response with a transient increase (3h), a decrease (1d), and further increase in the long-term after ADX. Sham animals showed a marked increase in corticosterone and ACTH levels three hours after surgery, with a decrease to basal levels thereafter. Plasma prolactin levels were not changed after ADX. CONCLUSION: There are different points of equilibrium in the HPA axis after the glucocorticoid negative feedback is removed. Prolactin plasma secretion is not altered in the short or long- term after ADX, suggesting that the peptidergic neurons essential for prolactin release are not activated after ADX.

Chronic unpredictable mild stress alters an anxiety-related defensive response, Fos immunoreactivity and hippocampal adult neurogenesis

Previous results show that elevated T-maze (ETM) avoidance responses are facilitated by acute restraint. Escape, on the other hand, was unaltered. To examine if the magnitude of the stressor is an important factor influencing these results, we investigated the effects of unpredictable chronic mild stress (UCMS) on ETM avoidance and escape measurements. Analysis of Fos protein immunoreactivity (Fos-ir) was used to map areas activated by stress exposure in response to ETM avoidance and escape performance. Additionally, the effects of the UCMS protocol on the number of cells expressing the marker of migrating neuroblasts doublecortin (DCX) in the hippocampus were investigated. Corticosterone serum levels were also measured. Results showed that UCMS facilitates ETM avoidance, not altering escape. In unstressed animals, avoidance performance increases Fos-ir in the cingulate cortex, hippocampus (dentate gyrus) and basomedial amygdala, and escape increases Fos-ir in the dorsolateral periaqueductal gray and locus ceruleus. In stressed animals submitted to ETM avoidance, increases in Fos-ir were observed in the cingulate cortex, ventrolateral septum, hippocampus, hypothalamus, amygdala, dorsal and median raphe nuclei. In stressed animals submitted to ETM escape, increases in Fos-ir were observed in the cingulate cortex, periaqueductal gray and locus ceruleus. Also, UCMS exposure decreased the number of DCX-positive cells in the dorsal and ventral hippocampus and increased corticosterone serum levels. These data suggest that the anxiogenic effects of UCMS are related to the activation of specific neurobiological circuits that modulate anxiety and confirm that this stress protocol activates the hypothalamus-pituitary-adrenal axis and decreases hippocampal adult neurogenesis.

Effects of thyroid status on NEI concentration in specific brain areas related to reproduction during the estrous cycle

We previously showed that short-term hypo- and hyperthyroidism induce changes in neuropeptide glutamic-acid-isoleucine-amide (NEI) concentrations in discrete brain areas in male rats. To investigate the possible effects of hypo- and hyperthyroidism on NEI concentrations mainly in hypothalamic areas related to reproduction and behavior, female rats were sacrificed at different days of the estrous cycle. Circulating luteinizing hormone (LH), estradiol and progesterone concentrations were measured in control, hypothyroid (hypoT, treated with PTU during 7-9 days) and hyperthyroid (hyperT, l-T4 during 4-7 days) animals. Both treatments blunted the LH surge. Hypo- and hyperthyroidism increased estradiol concentrations during proestrus afternoon (P-PM), although hypoT rats showed lower values compared to control during proestrus morning (P-AM). Progesterone levels were higher in all groups at P-PM and in the hyperT during diestrus morning (D2). NEI concentrations were lower in hypoT rats during the estrous cycle except in estrus (E) in the peduncular part of the lateral hypothalamus (PLH). They were also reduced by both treatments in the perifornical part of the lateral hypothalamus (PeFLH) during P-PM. Hypothyroidism led to higher NEI concentrations during P-PM in the organum vasculosum of the lamina terminalis and anteroventral periventricular nucleus (OVLT+AVPV). The present results indicate that NEI concentration is regulated in a complex manner by hypo- and hyperthyroidism in the different areas studied, suggesting a correlation between NEI values and the variations of gonadal steroid levels during estrous cycle. These changes could be, in part, responsible for the alterations observed in the hypothalamic-pituitary-gonadal axis in these pathologies.

Atypical presentation of a hormonally active adrenocortical tumor in an adolescent leading to delayed diagnosis

Adrenocortical tumors are rare in children and present with variable signs depending on the type of hormone excess. We herein describe the unusual presentation of a child with adrenocortical tumor and introduce the concept of in vitro chemosensitivity testing. CASE REPORT: A 10.5-year-old girl presented with hypertrichosis/hirsutism and weight loss. The weight loss and behavioral problems, associated with halted puberty and growth, led to the initial diagnosis of anorexia nervosa. However, subsequent weight gain but persisting arrest in growth and puberty and the appearance of central fat distribution prompted further evaluation. RESULTS AND FOLLOW-UP: 24h-urine free cortisol was elevated. Morning plasma ACTH was undetectable, while cortisol was elevated and circadian rhythmicity was absent. Thus a hormonally active adrenal cortical tumor (ACT) was suspected. On magnetic resonance imaging (MRI) a unilateral, encapsulated tumor was found which was subsequently removed surgically. Tissue was investigated histologically and for chemosensitivity in primary cell cultures. Although there were some risk factors for malignancy, the tumor was found to be a typical adenoma. Despite this histology, tumor cells survived in culture and were sensitive to cisplatin in combination with gemcitabine or paclitaxel. At surgery, the patient was started on hydrocortisone replacement which was unsuccessfully tapered over 3 months. Full recovery of the hypothalamus-pituitary-adrenal axis occurred only after 3 years. CONCLUSIONS: The diagnosis of a hormonally active adrenocortical tumor is often delayed because of atypical presentation. Cortisol replacement following unilateral tumor excision is mandatory and may be required for months or years. Individualized chemosensitivity studies carried out on primary cultures established from the tumor tissue itself may provide a tool in evaluating the effectiveness of chemotherapeutic drugs in the event that the adrenocortical tumor may prove to be carcinoma.