Pregnancy Associated Breast Cancer Among Israeli BRCA1/BRCA2 Carriers in a High-Risk Clinic

RATIONALE AND OBJECTIVES

Female carriers of pathogenic sequence variants (PSVs) in the BRCA1 /BRCA2 (Breast Cancer gene - BRCA) genes are at a substantially high-risk for developing breast cancer (BC), hence are offered active surveillance scheme based on semiannual breast exam and imaging from age 25 years to facilitate BC early detection (mammography/breast ultrasound depending on the age, and MRI). However, there are not specific guidelines for screening in case of pregnancy or lactation. In the current study, we summarize the experience at the largest high-risk clinic in Israel.

MATERIALS AND METHODS

Data of consecutive BRCA-PSV carriers undergoing surveillance as well as diagnostic ultrasound at the Meirav high-risk clinic from January 2014 to 2021 who were pregnant and/or breastfeeding at time of follow-up were identified. Relevant clinical data including results of breast exam, breast ultrasonography, biopsies and histological results were retrieved. Percentage of biopsies with malignancy, cancer detection rate and positive predictive values were calculated. Data is presented in descriptive statistics.

RESULTS

A total of 263 BRCA-carriers were included. Of these, 593 breast-ultrasonograms were performed in 263 BRCA-carriers for 292 pregnancies and 409 breast-ultrasonograms for 175 breastfeeding carriers. Of 36 breast biopsies in 292 pregnancies, 4 (PPV = 11%) had BC diagnosed (high grade invasive). Of 175 breastfeeding women, 25 biopsies were performed and 2 (PPV = 8%) were high grade invasive BC. Five of 6 BC were diagnosed in BRCA1 carriers, and 4/6 were screen detected. The rate of pregnancy-associated breast cancer was 6/292 (2.05%).

CONCLUSION

The overall detection rate of pregnancy-associated BC in BRCA-carriers is relatively low (2.05%), but still much higher than that in the general population. Two thirds of the BC were detected by screening. Therefore, despite the changes of the glandular breast tissue at time of pregnancy and breastfeeding, screening plays an important role in early detection. Ultrasound should be considered as a screening tool during this period of life of high-risk patients.

Kelly Punch Punctoplasty and Simple Punctal Dilatation Are Equally Effective for Punctal Stenosis: A Prospective Study

PURPOSE

To examine the clinical, imaging, and histopathologic differences between Kelly punch punctoplasty and punctal dilatation, both with mini Monoka stent insertion.

METHODS

This is a prospective, comparative clinical study. Patients with bilateral punctal stenosis and for whom surgery was advised participated in the study. The right eye underwent Kelly punch punctoplasty and the left eye simple punctal dilatation, both with mini Monoka stents were participated. Data were collected and analyzed before and 3 months following the procedure and included the degree of epiphora (Munk score) and punctal size as measured by anterior segment optical coherence tomography (AC- OCT). All specimens removed by the Kelly punch punctoplasty were sent for histopathologic evaluation, including Masson's trichome muscle staining.

RESULTS

The study included 46 eyes of 23 patients (4 males and 19 females) whose mean age at presentation was 60.43 ± 14.81 years (range 19-84 years). There was a significant decrease in the Munk score after both punctoplasties compared with baseline values (P < 0.01, matched pairs). There were no significant differences between groups in the delta Munk score. There was a significant increase in punctal size after both procedures compared with baseline values as measured by AS-OCT. Horner-Duverney's muscle was visible in only 3 of the 23 (13.04%) specimens from patients who underwent the Kelly punch punctoplasty.

CONCLUSIONS

The Kelly punch punctoplasty and the simple dilator punctoplasty, both with stents, are equally effective treatments for epiphora due to acquired punctal stenosis. Only a few specimens removed during the Kelly punch method show muscle fibers.

Outcomes after Surgery for Early Stage Breast Cancer in Women Staged With Preoperative Breast Magnetic Resonance Imaging According to Breast Tissue Density

PURPOSE

To determine surgical outcomes and breast cancer disease-free survival outcomes of women with early stage breast cancer with and without use of preoperative breast MRI according to breast tissue density.

METHODS

Women with early stage breast cancer diagnosed from 2004 to 2009 were classified into 2 groups: 1) those with dense and heterogeneously dense breasts (DB); 2) those with nondense breasts (NDB) (scattered fibroglandular and fatty replaced tissue). The 2 groups were reviewed to determine who underwent preoperative MRI. Breast tissue density was determined with mammography according to ACR BI-RADS. Patients were compared according to tumor size, grade, stage, and treatment. Survival analysis was performed using Kaplan-Meier estimates.

RESULTS

In total, 261 patients with mean follow-up of 85 months (25-133) were included: 156 DB and 105 NDB. Disease-free survival outcomes were better in the DB group in patients with MRI than in those without MRI: patients with MRI had significantly fewer local recurrences (P < 0.016) and metachronous contralateral breast cancers (P < 0.001), but this was not the case in the NDB group. Mastectomies were higher in the DB group with preoperative MRI than in those without MRI (P < 0.01), as it was in the NDB group (P > 0.05).

CONCLUSIONS

Preoperative breast MRI was associated with reduced local recurrence and metachronous contralateral cancers in the DB group, but not in the NDB group; however, the DB patients with MRI had higher mastectomy rates.

Early mortality in metastatic lung cancer: A SEER population data analysis

9103

Background: Millions of dollars invested in improving outcomes for metastatic lung cancer patients are essentially aimed at extending long term survival, with significant benefits being achieved over the last decade. However, little is known about lung cancer patients who die rapidly after diagnosis, potentially being deprived of these advances. We analyzed population-based data to describe real-world outcomes in metastatic lung cancer patients focusing on patients with early mortality. Methods: Using the Survival, Epidemiology and End Results (SEER) Database we analyzed adult metastatic lung cancers diagnosed between 1994-2014. This period was divided into 3 equal time periods: 1994-2000 (TP1), 2001-2007 (TP2) and 2008-2014 (TP3). Early mortality was defined as death within 2 months of diagnosis. Correlations between categorical variables were analyzed with chi squared tests and survival was analyzed using the Kaplan-Meier method. Results: Of 276,527 patients diagnosed with metastatic lung cancer, median age was 67 (range 20-105) and 154,465 (56%) were males. Thirty eight percent (103,830) of all patients died within 2 months of diagnosis. Of these early deaths, 96,344 (92.8%) were due to lung cancer. While the 2-year survival almost doubled from TP1 compared to TP3 (6% vs 11%, p < 0.001), the percentage of patients who died within 2 months only marginally improved (39.7% vs. 36.2% in TP1 vs TP3, respectively). For patients surviving at least 2 months, 2-year survival increased from 10% to 18% in TP1 vs TP3 (p < 0.001). Factors associated with early mortality include age > 65 (45% vs 31%), unmarried status (42% vs 34%), male sex (39% vs 36%), liver metastases (47% vs 32%) and large cell carcinoma vs adenocarcinoma (44% vs 36%) (all p < 0.001). Conclusions: While there has been a steady improvement in the long-term overall survival of patients with metastatic lung cancer, over one third of patients still die within 2 months of diagnosis. This has only marginally improved in the last 20 years. Research is urgently needed to identify causative and treatable factors.

Ciliated hepatic foregut cyst with high intra-cystic carbohydrate antigen 19-9 level

A ciliated hepatic foregut cyst (CHFC) is a rare foregut developmental malformation usually diagnosed in adulthood. Five percent of reported cases of CHFC transform into squamous cell carcinoma. We report the presentation, evaluation, and surgical management of a symptomatic 45-year-old male found to have a 6.2 cm CHFC. Contrast tomography-guided fine-needle aspiration demonstrated columnar, ciliated epithelium consistent with the histologic diagnosis of CHFC. The intracystic levels of carbohydrate antigen (CA) 19-9 and carcinoembryonic antigen (CEA) were extremely high (978118 U/mL and 973 μg/L, respectively). Histologically, the wall of the cyst showed characteristic pseudopapillae lined with a ciliated stratified columnar epithelium, underlying smooth muscle, an outer fibrous layer and no atypia. Immunohistochemistry for CA19-9 and CEA was positive. This is the first case report of a CHFC in which levels of CA 19-9 and CEA were measured. Our findings suggest that a large sized multilocular cyst and elevated cyst CA19-9 and CEA levels do not exclude a CHFC from consideration in the diagnosis. CHFCs should be included in the differential diagnosis of hepatic lesions. Accurate diagnosis of a CHFC is necessary given its potential for malignant transformation, and surgical excision is recommended.

Brain interleukin-1 mediates chronic stress-induced depression in mice via adrenocortical activation and hippocampal neurogenesis suppression

Several lines of evidence implicate the pro-inflammatory cytokine interleukin-1 (IL-1) in the etiology and pathophysiology of major depression. To explore the role of IL-1 in chronic stress-induced depression and some of its underlying biological mechanisms, we used the chronic mild stress (CMS) model of depression. Mice subjected to CMS for 5 weeks exhibited depressive-like symptoms, including decreased sucrose preference, reduced social exploration and adrenocortical activation, concomitantly with increased IL-1 beta levels in the hippocampus. In contrast, mice with deletion of the IL-1 receptor type I (IL-1rKO) or mice with transgenic, brain-restricted overexpression of IL-1 receptor antagonist did not display CMS-induced behavioral or neuroendocrine changes. Similarly, whereas in wild-type (WT) mice CMS significantly reduced hippocampal neurogenesis, measured by incorporation of bromodeoxyuridine (BrdU) and by doublecortin immunohistochemistry, no such decrease was observed IL-1rKO mice. The blunting of the adrenocortical activation in IL-1rKO mice may play a causal role in their resistance to depression, because removal of endogenous glucocorticoids by adrenalectomy also abolished the depressive-like effects of CMS, whereas chronic administration of corticosterone for 4 weeks produced depressive symptoms and reduced neurogenesis in both WT and IL-1rKO mice. The effects of CMS on both behavioral depression and neurogenesis could be mimicked by exogenous subcutaneous administration of IL-1 beta via osmotic minipumps for 4 weeks. These findings indicate that elevation in brain IL-1 levels, which characterizes many medical conditions, is both necessary and sufficient for producing the high incidence of depression found in these conditions. Thus, procedures aimed at reducing brain IL-1 levels may have potent antidepressive actions.

Interleukin-1 signaling modulates stress-induced analgesia

Exposure to stressful stimuli is often accompanied by reduced pain sensitivity, termed "stress-induced analgesia" (SIA). In the present study, the hypothesis that interleukin-1 (IL-1) may play a modulatory role in SIA was examined. Two genetic mouse models impaired in IL-1-signaling and their wild-type (WT) controls were employed. Another group of C57 mice was acutely administered with IL-1 receptor antagonist (IL-1ra). Mice were exposed to 2min swim stress at one of three water temperatures: 32 degrees C (mild stress), 20-23 degrees C (moderate stress), or 15 degrees C (severe stress); and then tested for pain sensitivity using the hot-plate test. Corticosterone levels were assessed in separate groups of WT and mutant mice following exposure to the three types of stress. Mild stress induced significant analgesia in the two WT strains and saline-treated mice, but not in the mutant strains or the IL-1ra-treated mice. Similarly, mild stress induced significantly elevated corticosterone levels in WT mice, and blunted corticosterone response in mutant mice. In contrast, both WT and mutant strains, as well as IL-1ra-treated mice, displayed analgesic and corticosterone responses following moderate and severe stress. Interestingly, the analgesic response to moderate stress was markedly potentiated in the mutant strains, as compared with their WT controls. The present results support our previous findings that in the absence of IL-1, stress response to mild stress is noticeably diminished. However, the analgesic response to moderate stress is markedly potentiated in mice with impaired IL-1 signaling, corroborating the anti-analgesic role of IL-1 in several pain modulatory conditions, including SIA.

Differential response to acute and repeated stress in cannabinoid CB1 receptor knockout newborn and adult mice

Previous studies have suggested that the endocannabinoid CB1 receptor (ECBR) system is involved in stress. However, the nature of this association is complex. Here, we investigated the role of CB1 receptors in the response to stress by comparing the effects of various stress modalities in CB1-/- receptor deficient and wild-type mice, at adulthood and during early development. Response to acute stress was assayed by plasma corticosterone (CS) and adrenocorticotrophic hormone (ACTH), USVs and motor inhibition. The response to repeated stress was assessed by USVs and motor inhibition. Since repeated bell stress seemed to cause a cumulative fear in CB1 receptor knockout mice, these behavioral responses were also compared to those observed after a single severe stress (forced swimming). In wild-type, but not in CB1 receptor knockout mice, bell stress-induced elevations of ACTH and CS were significant. The first exposure to bell stress had no significant effect on USVs or mobility. Upon repeated exposures, significant suppression of USVs, together with behavioral inhibition, were observed in CB1 knockout but not in wild-type mice. Swim stress inhibited USVs in the knockout animals, and the profound motor inhibition displayed by all animals was greater and more prolonged in the CB1-/- mice. Since the knockout mice lack the CB1 receptor throughout pre- and postnatal life, the stress response in pups was also assayed (by separation-induced USVs). Wild-type pups displayed the characteristic developmental peak in USV emissions; it was completely lacking in knockout pups. We conclude that acutely, the absence of CB1 receptors reduces the neuroendocrine response and does not affect the behavioral response to moderate stress. However, upon repeated stress or acute severe stress, CB1 receptor deficiency causes persistent behavioral inhibition. Finally, the CB1 receptor plays a role in modulating the stress response from an early age. These observations suggest that CB1 receptors participate in the mediation of the stress response and that the absence of these receptors results in a greater vulnerability to stress. We suggest that the stress-induced endocrine and behavioral suppression in CB1 receptor deficient mice may serve as a model for some forms of post-traumatic stress disorder (PTSD). Further, the role of CB1 receptors in coping with stress is a lifelong function. Finally, although equivalent research has not been performed in human infants, the postnatal suppression of the stress response in CB1 receptor knockout pups may have implications when cannabinoid-based therapy is considered for children.

Diverse effects of stress and additional adrenocorticotropic hormone on digitalis-like compounds in normal and nude mice

Digitalis-like compounds (DLC) are steroidal hormones that are synthesized in, and released from, the adrenal gland, whose regulation may be directed by the hypothalamic-pituitary-adrenal (HPA) axis. Increasing evidence points to antitumour properties of these compounds and we hypothesized that the establishment of tumours in athymic nude mice may be facilitated by an abnormal synthesis or secretion of DLC. To explore this hypothesis, DLC concentrations were determined in the plasma, and in adrenal and hypothalamic tissues of nude compared to normal mice under basal conditions, and 30 min after a stress stimulus (i.p. injection of 100 micro l saline) with or without additional adrenocorticotropic hormone (ACTH) 1 micro g/per animal. Simultaneously, plasma corticosterone and serum adrenocorticotropic hormone (ACTH) concentrations were analysed. The basal DLC concentrations were similar in the plasma and the hypothalamus of both strains, whereas the basal adrenal DLC concentration was significantly lower in the nude mice compared to normal mice. The stress stimulus induced in normal mice a significant increase in DLC concentrations in the adrenal gland, the plasma and the hypothalamus. However, in nude mice, it caused an increase only in the adrenal gland and the hypothalamus, whereas the plasma DLC concentration was not affected. In both strains, the administration of ACTH in addition to injection stress did not provoke a further increase in DLC concentrations while inducing a significant increase in plasma corticosterone concentration. Regardless of the applied stimulus, the nude mice expressed significant lower DLC concentrations in the adrenal gland and the plasma compared to normal mice. The low basal adrenal DLC concentration in nude mice and their impaired DLC response towards stress- and ACTH stimulation both support an involvement of DLC in tumorigenesis.

Virus and host factors that mediate the clinical and behavioral signs of experimental herpetic encephalitis. A short auto-review

Experimental models that mimic the clinical syndrome of human viral encephalitis and represent HSV-1 neurotropism were utilized to investigate neuro-pharmacologic changes mediating clinical and behavioral manifestations of encephalitic infection of the central nervous system with HSV-1-induced rapid activation of the hypothalamic--pituitary--adrenocortical (HPA) axis and production of brain derived interleukin-1 (IL-1) and prostaglandin E2 (PG-E2), independently of viral replication. HSV-1 infection induced clinical signs of fever, motor hyperactivity and aggressive behavior. These manifestations were dependent on a permissive action of circulating glucocorticoids and not related to the degree of viral replication in the brain. Hyperthermia and HPA axis activation were also specifically dependent on HSV-1-induced brain IL-1 and PG-E2. The chronic neurological sequel or fatal outcome of HSV-1 encephalitis may be due to viral replication and brain tissue destruction, which are dependent on virus encoded virulence genes. In contrast, the clinical and behavioral signs in the acute phase are a result of activation of neurochemical systems, including cytokines, prostaglandinds and catecholamines. Circulating glucocorticoids play an essential role in mediating the physiologic actions of HSV-1-induced brain products and the clinical syndrome of encephalitis.

The role of endogenous interleukin-1 in stress-induced adrenal activation and adrenalectomy-induced adrenocorticotropic hormone hypersecretion

To examine the role of IL-1 in the regulation of the hypothalamo-pituitary-adrenal (HPA) axis, mice with knockout of the IL-1 receptor type I (IL-1rKO) were exposed to psychological and metabolic stressors. When exposed to mild stressors (auditory stress or a low dose of 2-deoxyglucose), IL-1rKO mice displayed a significantly diminished corticosterone secretion, compared with wild-type (WT) controls. In response to more severe stressors (60-min restraint or a high dose of 2-deoxyglucose), both groups exhibited a similar increase in corticosterone secretion. To examine the role of IL-1 in HPA axis feedback regulation, serum ACTH levels were measured after adrenalectomy (ADX) in IL-1rKO mice and in mice with transgenic overexpression of IL-1 receptor antagonist within the brain (IL-1raTG). As expected, WT controls exhibited ADX-induced ACTH hypersecretion, whereas IL-1rKO and IL-1raTG mice showed no increase in ACTH levels, suggesting that brain IL-1 has a critical role in ADX-associated ACTH hypersecretion. Similarly, WT mice that were chronically exposed to IL-1ra in utero displayed a diminished ADX-induced ACTH hypersecretion, compared with vehicle-treated controls, suggesting a developmental role of IL-1 in HPA axis regulation. In conclusion, our results suggest that endogenous IL-1 plays a critical role in HPA axis activation after stress and ADX.

The EAE-associated behavioral syndrome: I. Temporal correlation with inflammatory mediators

To elucidate the mechanisms underlying the EAE-associated behavioral syndrome (EBS), we examined the temporal correlation between the behavioral alterations and inflammatory processes. Onset of the behavioral syndrome was associated with the onset of brain infiltration, as well as mRNA expression of interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) and elevated production of interleukin 1 beta protein and prostaglandin E(2) (PGE(2)). Sickness behavior symptoms coincided with peak cytokine expression. Behavioral recovery was associated with a reduction of cytokine expression, but not infiltration, PGE(2) production or motor disturbances. These results suggest that inflammatory processes in general, and the production of pro-inflammatory cytokines in particular, are involved in mediating EAE-associated sickness behavior.

A novel permissive role for glucocorticoids in induction of febrile and behavioral signs of experimental herpes simplex virus encephalitis

Herpes simplex virus type 1 (HSV-1) encephalitis may present with fever and behavioral changes, to the extent of a psychotic state and psychomotor agitation. We developed a clinically relevant experimental model of HSV-1 encephalitis and investigated host brain responses associated with its clinical signs and whether these responses depend on the presence of circulating glucocorticoids. Intracerebral inoculation of HSV-1 in rats induced fever, motor hyperactivity and aggressive behavior. In adrenalectomized rats HSV-1 failed to induce these signs, although mortality rate was identical to sham-operated rats. Hypophysectomy or blocking glucocorticoid receptors also prevented HSV-1-induced fever. Dexamethasone replacement therapy to adrenalectomized rats restored the HSV-1-induced fever and behavioral abnormalities. HSV-1 inoculation produced hyperproduction of prostaglandin E(2) by brain slices. This effect was abolished in adrenalectomized rats and was restored by dexamethasone treatment. In intact rats HSV-1 induced brain interleukin-1beta (IL-1beta) gene expression. Adrenalectomy alone caused brain IL-1beta expression, which did not increase after HSV-1 infection. Similarly, HSV-1 induced IL-1beta expression in astrocyte cultures. Removal of cortisol from the culture medium caused basal IL-1beta mRNA expression which was not increased by infection. In conclusion, fever, motor hyperactivity and aggressive behavior during experimental HSV-1 encephalitis are dependent on brain responses, including prostaglandin E(2) and IL-1beta synthesis. Circulating glucocorticoids play an essential permissive role in the induction of these host brain responses.

Acute effects of purified and UV-inactivated Herpes simplex virus type 1 on the hypothalamo-pituitary-adrenocortical axis

Herpes simplex virus type 1 (HSV-1) is a common cause of viral encephalitis, manifested by neuroendocrine and behavioral changes. We have previously demonstrated that HSV-1 induces marked hypothalamo-pituitary-adrenocortical (HPA) axis activation. In this study we characterized the acute effects of HSV-1 on the HPA axis occurring before viral replication and appearance of clinical signs of encephalitis. Since in previous studies we used crude virus preparations which may contain immune factors produced by the infected cells, we tested here the effects of purified HSV-1 virions. HSV-1 was propagated on Vero cells and virions were purified by centrifugation in sucrose gradients. Inactivation of viral infectivity was achieved by UV-irradiation, which caused a million-fold decrease in virus titer, as determined by plaque assay. Intracerebroventricular (ICV) inoculation of crude or purified virions induced a dose dependent increase in serum corticosterone and corticotropin (ACTH). This effect was maximal within 3.5 h postinfection and lasted for 72 h. ICV inoculation of UV-inactivated purified virions caused a marked increase in serum corticosterone and ACTH at 3.5 h, but in contrast to the effect of the active virus, the hormone levels gradually decreased at 24 h, and returned to basal levels at 72 h postinfection. HSV-1-induced HPA axis activation at 3.5 h was completely abolished by pretreatment with interleukin-1 receptor antagonist, injected ICV. Adrenalectomized rats failed to respond to ICV inoculation of purified HSV-1 by increase in ACTH. In contrast, these rats responded to ICV injection of LPS.

IN CONCLUSION

(1) HSV-1 can acutely activate the HPA axis before and independently of any viral replication; (2) HSV-1-induced HPA axis activation depends on a permissive action of circulating glucocorticoids and on host derived brain interleukin-1.

Electrical stimulation of the dorsal hippocampus caused a long lasting inhibition of ACTH and adrenocortical responses to photic stimuli in freely moving rats

The effect of a single train of electrical hippocampal stimulation on ACTH and corticosterone (CS) responses to subsequent photic stimulation was studied in freely moving male rats. The hippocampal stimulation inhibited the stress-induced rise [corrected] in serum CS levels up to 150 h when compared to sham stimulated animals. This effect did not exist at 300 h following stimulation. This sustained hippocampal inhibitory effect on the adrenocortical response, which was not reported previously, was partially abolished by section of the dorsal fornix. The present data demonstrate that dorsal hippocampal stimulation has a long lasting inhibitory effect on pituitary adrenocortical secretion following neural stimuli and this is partially mediated by the dorsal fornix.

Evaluation of the effect of stress on the blood--brain barrier: critical role of the brain perfusion time

The Gulf war syndrome has drawn increased attention in the issue of the effect of stress on the blood-brain barrier (BBB). We have applied various stressful modalities and tested BBB disruption as measured by the amount of Evans blue (EB) retained by brain parenchyma. We have evaluated the retention of this marker as a function of the perfusion time of the brain following stress. This was done to distinguish between the marker retained in the lumen of small blood vessels and the marker retained by the brain parenchyma. Mice were exposed to either short swim stress or restraint stress. In mice exposed to either swim or restraint stress that were perfused for 1 min, the amount of EB retained in the brain was significantly higher as compared to non-stressed controls. Fifteen min perfusion markedly reduced the EB brain content to levels found in the non-stressed animals. In rats exposed to neural or metabolic stressful stimuli and perfused for 15 min, the EB content was similar to non-stressed controls. Our results demonstrate that various stress modalities have no effect on the BBB permeability and insufficient wash of blood vessels by perfusion may cause misinterpretation of permeability studies.

Effects of antidepressant drugs on the behavioral and physiological responses to lipopolysaccharide (LPS) in rodents

Antidepressants produce various immunomodulatory effects, as well as an attenuation of the behavioral responses to immune challenges, such as lipopolysaccharide (LPS). To explore further the effects of antidepressants on neuroimmune interactions, rats were treated daily with either fluoxetine (Prozac) or saline for 5 weeks, and various behavioral, neuroendocrine, and immune functions were measured following administration of either LPS or saline. Chronic fluoxetine treatment significantly attenuated the anorexia and body weight loss, as well as the depletion of CRH-41 from the median eminence and the elevation in serum corticosterone levels induced by LPS. Chronic treatment with imipramine also attenuated LPS-induced adrenocortical activation. In rats and in mice, which normally display a biphasic body temperature response to LPS (initial hypothermia followed by hyperthermia), chronic treatment with fluoxetine completely abolished the hypothermic response and facilitated and strengthened the hyperthermic response. The effects of antidepressants on the responsiveness to LPS are probably not mediated by their effects on peripheral proinflammatory cytokine production, because LPS-induced expression of TNFalpha and IL-1beta mRNA in the spleen (assessed by semiquantitative in situ hybridization) was not altered following chronic treatment with either fluoxetine or imipramine. The effects of antidepressants on the acute phase response may have important clinical implications for the psychiatric and neuroendocrine disturbances that are commonly associated with various medical conditions.

Illness, cytokines, and depression

Various medical conditions that involve activation of the immune system are associated with psychological and neuroendocrine changes that resemble the characteristics of depression. In this review we present our recent studies, designed to investigate the relationship between the behavioral effects of immune activation and depressive symptomatology. In the first set of experiments, we used a double-blind prospective design to investigate the psychological consequences of illness in two models: (1) vaccination of teenage girls with live attenuated rubella virus, and (2) lipopolysaccharide (LPS) administration in healthy male volunteers. In the rubella study, we demonstrated that, compared to control group subjects and to their own baseline, a subgroup of vulnerable individuals (girls from low socioeconomic status) showed a significant virus-induced increase in depressed mood up to 10 weeks after vaccination. In an ongoing study on the effects of LPS, we demonstrated significant LPS-induced elevation in the levels of depression and anxiety as well as memory deficits. These psychological effects were highly correlated with the levels of LPS-induced cytokine secretion. In parallel experiments, we demonstrated in rodents that immune activation with various acute and chronic immune challenges induces a depressive-like syndrome, characterized by anhedonia, anorexia, body weight loss, and reduced locomotor, exploratory, and social behavior. Chronic treatment with antidepressants (imipramine or fluoxetine) attenuated many of the behavioral effects of LPS, as well as LPS-induced changes in body temperature, adrenocortical activation, hypothalamic serotonin release, and the expression of splenic TNF-alpha mRNA. Taken together, these findings suggest that cytokines are involved in the etiology and symptomatology of illness-associated depression.

Effect of Mycoplasma fermentans on brain PGE(2): role of glucocorticoids and their receptors

OBJECTIVES

Mycoplasmas are a group of eubacteria, which cause various diseases in animals and in humans, and can contribute to diseases produced by other infectious agents, particularly HIV. We have recently reported that intracerebral administration of Mycoplasma fermentans (MF) produces both neuroendocrine and behavioral alterations. Some of these responses were mediated by MF-induced production of prostaglandin E(2 )(PGE(2)). The aim of this study was to examine the role of glucocorticoids (GC) in regulating MF-induced brain prostaglandin production.

METHODS

Male rats were injected intracerebroventricularly with various doses of heat-inactivated MF, LPS or IL-1 beta and the following parameters were measured: (1) ex vivo production of hippocampal PGE(2), (2) serum levels of ACTH and corticosterone, and (3) binding capacity of [(3)H]-dexamethasone (DEX) to hippocampal cytosol.

RESULTS

MF caused a small increase in hippocampal PGE(2) production, but higher doses failed to produce a further increase. In contrast, the effects of LPS or IL-1 beta on PGE(2) were dose-dependent. Removal of circulating GC by bilateral adrenalectomy significantly enhanced MF-induced brain PGE(2) production. The three immune stimulators increased serum levels of ACTH and corticosterone to the same extent. Finally, MF, but not IL-1 beta increased the specific binding of [(3)H]-DEX to hippocampal cytosol.

CONCLUSIONS

Brain PGE(2) induced by MF is regulated by endogenous GC. These hormones have an attenuating effect on PGE(2 )production, probably through an MF-induced increase in GC binding by brain tissue. This mechanism may be important in the pathological effect of MF within the brain of AIDS patients.

Effects of adrenalectomy and corticosterone replacement on the hypothalamic-pituitary response to neural stimuli

In this study we examined whether circulating glucocorticoids (GC) have a permissive facilitatory role in the hypothalamo-pituitary-adrenal (HPA) axis responses to neural or metabolic stimuli. In control sham operated rats the exposure to photic or acoustic neural stimuli and to either cytoglucopenia induced by 2-deoxyglucose (2-DG) or to hypoglycemia induced by insulin caused a significant 5-fold increase in serum ACTH as compared to basal non-stress levels. In adrenalectomized (Adex) rats tested under basal conditions at 4, 7 and 14 days post-Adex, serum ACTH gradually increased in a time-dependent manner, Also, at 4 days post-Adex the median eminence (ME) content of CRH-41 was markedly depleted but gradually recovered to control levels at 7 and 14 days post-Adex. The serum ACTH responses to both photic and acoustic stimuli tested at the same time points were completely inhibited. In contrast, administration of either insulin or 2-DG caused a marked increase in serum ACTH levels. In Adex rats, implanted with low corticosterone (CS) pellets which produced basal serum levels of CS, ME CRH-41 levels and serum ACTH were similar to control sham operated animals. Exposure to both neural stimuli resulted in a significant depletion in CRH-41 ME content and in a rise in serum ACTH as in the respective controls. On the other hand in rats implanted with high CS pellets which produced stress typical CS serum levels, the ME CRH-41 and serum ACTH responses to both stimuli were markedly inhibited. These results suggest that (1) the HPA axis responses to neural stimuli but not to metabolic stimuli require the presence of circulating GC (2), the lack of ACTH response to neural stimuli in Adex rats may not be related to the low CRH-41 ME content.

Effects of adrenergic and serotonergic agonists in the amygdala on the hypothalamo-pituitary-adrenocortical axis

The effect of direct administration of adrenergic and serotonergic (5-HT) agonists into the central nucleus of the amygdala (AMG) on the hypothalamo-pituitary-adrenal (HPA) axis have been studied in intact male rats and in animals with 6-hydroxydopamine (6-OHDA) or 5, 7-dihydroxytryptamine (5,7-DHT) neurotoxic lesions in the paraventricular nucleus of the hypothalamus (PVN). In intact animals, the administration of phenylephrine, an alpha1 adrenergic agonist or 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) a 5-HT(1A) agonist caused depletion of median eminence corticotropin releasing hormone and a rise in serum adrenocorticotrophic hormone (ACTH) and corticosterone (CS) levels. Isoproterenol a beta agonist was more effective than phenylephrine and a 5-HT(1B) agonist CP-93, 129 was less effective than 8-OH-DPAT on the adrenocortical activity. The 6-OHDA or 5,7-DHT hypothalamic lesions prevented the stimulatory effects of phenylephrine and 8-OH-DPAT, respectively, which where injected into the AMG, on serum ACTH and CS levels. In view of our previous studies on the effects of the adrenergic and 5-HT antagonists in the AMG and the present data, it is suggested that norepinephrine and 5-HT play an important role in the stimulatory effect of the AMG on the HPA axis. These effects depend on the presence of these excitatory neurotransmitters in the PVN.

Effects of sex hormones on experimental autoimmune myasthenia gravis

To examine whether exacerbation of myasthenia gravis (MG) can be induced by changes in sex hormone levels we immunized 20 female Lewis rats with torpedo antigen to induce experimental autoimmune MG (EAMG). Ten of the animals underwent surgical ovariectomy prior to the induction of EAMG and 10 served as controls. Anti-acetylcholine receptor antibody (AChR-ab) titres and the degree of decrement on repetitive stimulation electromyography (REMG) at 3 Hz were obtained at base line and compared between rats with and without ovariectomy and a second control group of naïve rats. Three rats in each group were then injected with excess oestrogen and progesterone for one week, and three of the remaining rats in each group were given sham injections, and the degree of decrement on REMG and AchR-ab titres were re-evaluated. Immune reactivity of peripheral lymphocytes and splenic lymphocytes from all groups and controls was also determined. A comparable number of animals with and without ovariectomy developed clinical and electromyographic EAMG. The extent of decrement on REMG and AChR-ab titres did not change following hormonal replacement. Lymphocyte reactivity was similar for rats with and without ovariectomy. In conclusion, sex hormones do not appear to have an influence on the susceptibility to and the severity of MG.

Activation of the adrenocortical axis by surgical stress: involvement of central norepinephrine and interleukin-1

In the present study, we examined the mechanisms involved in the activation of the adrenocortical axis following surgical stress. Adult male rats underwent surgical laparotomy or craniotomy under ether anesthesia while control rats were only ether-anesthetized. Four hours following laparotomy or craniotomy, serum adrenocorticotropin (ACTH) and corticosterone (CS) were significantly increased and returned to almost basal levels after 24 h. Laparotomy also caused a significant depletion of corticotropin-releasing hormone (CRH-41) in the median eminence (ME). Pretreatment with dexamethasone 50 microg/kg completely abolished the pituitary-adrenal response while pretreatment with type II corticosteroid receptor antagonist caused a significant hypersecretion of both ACTH and CS and inhibited the effect of dexamethasone. The response to laparotomy was markedly attenuated in rats injected with 6-hydroxydopamine into the paraventricular nucleus (PVN) which significantly depletes norepinephrine (NE) PVN content. Intracerebroventricular injection of interleukin-1 receptor antagonist (IL-1ra) also inhibited the pituitary-adrenal response to laparotomy. The results suggest that (1) surgical stress activates the hypothalamo-pituitary-adrenal (HPA) axis via a mechanism which involves the release of CRH from the ME and NE input to the PVN; (2) the adrenocortical response is sensitive to the negative feedback of glucocorticoids via the mediation of type II glucocorticoid receptors, and (3) central IL-1 may be a mediator in the HPA axis response to surgical stress.

Effect of exogenous nitric oxide and inhibitors of nitric oxide synthase on the hypothalamic pituitary adrenal axis responses to neural stimuli

It has been shown that the hypothalamic-pituitary-adrenal (HPA) axis responses to immune-derived stimuli in particular can be modulated by nitric oxide (NO). In the present study we examined the effect of endogenous and exogenous NO on the HPA axis responses to neural stimuli which are not related to immune functions. Intracerebroventricular injection of NOR-3, a donor of NO, had no effect on basal HPA axis activity but significantly attenuated the secretion of median eminence (ME) CRH-41 as well as the serum ACTH and corticosterone (CS) in response to acute photic stimulation in a dose-dependent manner. Intracerebroventricular administration of N-omega-nitro-L-arginine methyl ester (L-NAME), a general NOS inhibitor, significantly enhanced ACTH and CS responses to this stress but did not change the basal levels of these hormones. On the other hand, i.c.v. injection of aminoguanidine, an inhibitor of inducible NO synthase (NOS) but not of neuronal NOS, did not affect the HPA axis responses to photic stimulation. These results suggest that: (1) NO is involved in modulation of the HPA axis responses to neural stimuli which are not dependent on immune factors, (2) the effect of NO is mediated by inhibition of hypothalamic ME CRH-41 secretion, and (3) this effect is probably mediated by neuronal NOS and not by inducible NOS.

The role of brain cytokines in mediating the behavioral and neuroendocrine effects of intracerebral mycoplasma fermentans

Intracerebral administration of Mycoplasma fermentans (MF), a small microorganism that has been found in the brain of some AIDS patients, induces behavioral and neuroendocrine alterations in rats. To examine the role of tumor necrosis factor-alpha (TNFalpha) and interleukin-1 (IL-1) in mediating these effects we measured MF-induced expression of TNFalpha and IL-1beta mRNA in various brain regions, and the effects of TNFalpha synthesis blockers and IL-1 receptor antagonist (IL-1ra) on MF-induced sickness behavior and adrenocortical activation. Intracerebroventricular (i.c.v.) administration of heat-inactivated MF induced the expression of both TNFalpha and IL-1beta mRNA in the cortex, dorsal hippocampus, amygdala, and hypothalamus. Pre-treatment of rats with either TNFalpha synthesis blockers, pentoxifylline or rolipram, or with IL-1ra did not attenuate MF-induced anorexia, body weight loss, and suppression of social behavior. However, simultaneous administration of both pentoxifylline and IL-1ra markedly attenuated MF-induced anorexia and body weight loss, but had no effect on the suppression of social behavior. Pre-treatment with pentoxifylline, but not with IL-1ra, significantly attenuated MF-induced corticosterone (CS) secretion. Together, these findings indicate that both TNFalpha and IL-1 participate, in a complementary manner, in mediating some of the behavioral effects of MF, whereas only TNFalpha, but not IL-1, is involved in mediating MF-induced adrenocortical activation. We suggest that cytokines within the brain are involved in mediating at least some of the neurobehavioral and neuroendocrine abnormalities that may be produced by MF in AIDS patients.

Glucocorticoid receptor antagonists in the hippocampus modify the negative feedback following neural stimuli

The effects of local glucocorticoid receptor antagonists implanted into the dorsal hippocampus on the hypothalamo-pituitary-adrenal (HPA) axis responses following neural stimuli in freely moving rats, as well as their effects on the negative feedback exerted by dexamethasone (DEX) was studied in male rats. In animals with hippocampal cholesterol implants, photic and acoustic stimuli caused depletion in median eminence (ME) CRH-41 and a consequent rise in plasma ACTH and corticosterone levels. These effects were inhibited by systemic DEX, and the latter phenomenon was partially reversed by hippocampal implants of glucocorticoid (GR) and to a lesser degree by mineralocorticoid (MR) receptor antagonists. These data indicate that GR and MR receptors in the hippocampus play a role in the glucocorticoid negative feedback on the HPA axis, although the hippocampus may have also a modulatory effect, which does not depend on glucocorticoids.

Cytokines inhibit sexual behavior in female rats: II. Prostaglandins mediate the suppressive effects of interleukin-1beta

The proinflammatory cytokine interleukin-1 (IL-1) induces several behavioral alterations that are characteristic of illness, such as anorexia and reduced locomotor and social activity. We have recently demonstrated that IL-1 inhibits sexual activity, motivation and attractivity in female, but not in male rats following either central or peripheral administration. In the present study we examined the involvement of prostaglandin (PG) synthesis in mediating IL-1-induced suppression of female sexual behavior. Administration of the cyclooxygenase blockers indomethacin or ibuprofen completely prevented IL-1-induced suppression of female sexual behavior, including the reduction in proceptive behavior, the lordosis response to a male's mounts, and the preference for a sexually active partner. In a subsequent study, ex-vivo release of hypothalamic PGE2 and the secretion of corticosterone (CS) were measured in males and estrous females following IL-1 administration. At the same time and dose of IL-1 administration that significantly reduced sexual behavior in female but not male rats, IL-1 produced a significant increase in PGE2 release in female, but not in male rats. In contrast, IL-1 induced a significant elevation of serum CS levels in males but not in females. These findings suggest that PG synthesis is involved in mediating the effects of IL-1 on female sexual behavior. Furthermore, differential secretion of PGs and CS may underlie the gender difference in the effects of IL-1 on sexual behavior.

Pardaxin, a new pharmacological tool to stimulate the arachidonic acid cascade in PC12 cells

The effect of Pardaxin, a neurotoxin that induces neurotransmitter release from neurons, on the arachidonic acid (AA) cascade was studied in PC12 cells. Both native and the synthetic Pardaxin selectively stimulated phospholipase A2 (PLA2) activity (measured by [3H]AA release) in the presence as well as in the absence of extracellular calcium. Pardaxin-stimulated PLA2 activity was also evident in the increased formation of lysophosphatidylcholine. Pardaxin analogs, lacking the alpha-helical structure that is essential for insertion into the plasma membrane, were ineffective in stimulating the AA cascade in PC12 cells. Pardaxin stimulation of PLA2 was markedly inhibited by the nonselective PLA2 inhibitors bromophenacyl bromide and mepacrine, by methyl arachidonyl fluorophosphonate, a dual inhibitor of calcium-dependent cytosolic PLA2 and the calcium-independent PLA2 and by bromoenol lactone[(E)-6-(bromoethylene)tetrahydro-3-(1-naphthalenyl-2H-pyran -2- one], a highly specific inhibitor of calcium-independent PLA2. After Pardaxin treatment, there was increased release of AA metabolites produced by the cyclooxygenase pathway as expressed in an 8-fold increase of PGE2 release. The release of other eicosanoids, such as 6-keto-PGF1alpha and thromboxane B2, was also augmented. Pardaxin-induced PGE2 release was observed in calcium-free medium and in the absence of any increase in cytosolic calcium. Dexamethasone partially inhibited Pardaxin-induced PGE2 release. This effect was reversed by the type II corticosteroid receptor antagonist RU-38486. Our results indicate that Pardaxin stimulates release of AA and eicosanoids, independently of calcium, and suggest that calcium-independent PLA2 plays an important role in Pardaxin stimulation of the AA cascade.

Role of serotonin in the amygdala in hypothalamo-pituitary-adrenocortical responses

In view of the fact that the amygdala (AMG) and hypothalamic serotonin (5-HT) have an excitatory effect on the hypothalamo-pituitary-adrenal (HPA) axis, we have investigated the role of 5-HT in the AMG on this response. In intact freely moving rats, a mildly stressing short photic stimulation caused depletion of median eminence CRH-41, due to its release into the portal circulation and a rise in serum ACTH and corticosterone levels. This effect was significantly inhibited in rats in which 5-HT was depleted in the AMG following local 5,7-dihydroxytryptamine administration, which did not affect hypothalamic 5-HT content. Also, local pretreatment with ketanserin (a 5-HT2 receptor antagonist) in the AMG had the same inhibitory effect on the HPA axis response. These results indicate that AMG 5-HT has an important role in the activation of the HPA axis following neural stimulation and that 5-HT2 receptors are involved.

The excitatory effects of the amygdala on hypothalamo-pituitary-adrenocortical responses are mediated by hypothalamic norepinephrine, serotonin, and CRF-41

The hypothalamic neural mechanisms that are involved in the facilitatory effects of the amygdala (AMG) on the hypothalamo-pituitary-adrenocortical (HPA) axis have been investigated in rats. Stimulation of the central AMG nucleus caused a depletion of hypothalamic CRF-41, presumably due to its release into the portal circulation, and a subsequent rise in plasma ACTH and corticosterone (CS) levels. These effects were inhibited in rats in which hypothalamic norepinephrine (NE) or serotonin (5-HT) was depleted by catecholamine or serotonin neurotoxins, respectively. Furthermore, the administration of prazosin, an alpha1, but not of atenolol, which is a beta-blocker, as well as administration of the 5-HT2 blocker ketanserin inhibited the ACTH and CS responses to AMG stimulation. These results indicate that the facilitatory effects of the AMG on the HPA axis are mediated by hypothalamic NE via alpha1 receptors and by 5-HT via 5-HT2 receptors, as well as by CRF-41 in the paraventricular nucleus.

Hypothalamic mechanisms mediating glutamate effects on the hypothalamo-pituitary-adrenocortical axis

The effect of local administration of glutamate into the hypothalamic paraventricular nucleus (PVN) on the hypothalamo-pituitary adrenocortical (HPA) axis was studied in male rats. Glutamate caused CRH-41 depletion from the median eminence (ME) and a consequent rise in ACTH and corticosterone (CS) serum levels. In rats pretreated with systemic dexamethasone (dex) these effects were completely inhibited. The administration of the glucocorticoid receptor antagonist RU-38486 abolished the inhibitory effect of dex on the adrenocortical discharge. In addition, the depletion of hypothalamic norepinephrine (NE) and serotonin (5-HT) by specific neurotoxins administered into the ventral noradrenergic blundle or into the raphe nuclei respectively, inhibited the response of serum ACTH and CS following PVN glutamate administration. These data indicate that glutamate stimulated the HPA axis via the release of ME CRH-41 into the portal circulation. This response is steroid sensitive involving type II glucocorticoid receptors. Hypothalamic NE and 5-HT participate in the glutamate induced HPA axis activation.

Protection against septic shock and suppression of tumor necrosis factor alpha and nitric oxide production by dexanabinol (HU-211), a nonpsychotropic cannabinoid

Dexanabinol, HU-211, a synthetic cannabinoid devoid of psychotropic effects, improves neurological outcome in models of brain trauma, ischemia and meningitis. Recently, HU-211 was found to inhibit brain tumor necrosis factor (TNFalpha) production after head injury. In the present study, we demonstrate the ability of HU-211 to suppress TNFalpha production and to rescue mice and rats from endotoxic shock after LPS (Escherichia coli 055:B5) inoculation. In BALB/c mice, a dose of 10 mg/kg LPS, injected i.p., caused 57% and 100% mortality, at 24 and 48 hr, respectively. HU-211, administered i.p. 30 min before lipopolysaccharide (LPS), reduced lethality to 9 and 67% at these time points (P < .05). When coinjected with D-galactoseamine (i.p.), LPS was 100% lethal within 24 hr, whereas eight hourly injections of HU-211 caused mortality of C57BL/6 mice to drop to 10% (P < .001). Administration of LPS to Sprague-Dawley rats resulted in a 30% reduction in the mean arterial blood pressure within 30 min, which persisted for 3 hr. HU-211, given 2 to 3 min before LPS, completely abolished the typical hypotensive response. Furthermore, the drug also markedly suppressed in vitro TNFalpha production and nitric oxide generation (by >90%) by both murine peritoneal macrophages and rat alveolar macrophage cell line exposed to LPS. HU-211 may, therefore, have therapeutic implications in the treatment of TNFalpha-mediated pathologies.

Linomide activates the adrenocortical axis in the rat: inhibition of experimental autoimmune encephalomyelitis by linomide is not related to the increase of corticosterone

Linomide is a synthetic compound that affects various immunological functions and inhibits experimental autoimmune encephalomyelitis (EAE). In the present study we evaluated the effect of linomide on the HPA axis functions under basal and stress-induced conditions and examined whether the effect of linomide on the HPA axis is involved in linomide-induced amelioration of EAE in rats. Linomide caused a significant increase of serum ACTH and corticosterone (CS). The adrenocortical response to various stress modalities as well as the negative feedback exerted by glucocorticoids was not affected. The marked reduction of thymus weight following linomide treatment was abrogated in adrenalectomized rats. The induction of EAE in adrenalectomized rats was completely inhibited by linomide treatment. These results suggest that the increased CS levels induced by linomide are responsible for the decrease in thymus weight but do not play a role in the therapeutic effect of this drug in EAE.

Characterization of the effect of Mycoplasma fermentans on the hypothalamo-pituitary-adrenal axis

The mechanisms involved in the activation of the hypothalamus-pituitary-adrenal axis after administration of Mycoplasma fermentans were examined. Male rats were injected intracerebroventricularly (i.c.v.) with heat-inactivated M. fermentas (6 micrograms protein/10 microliters/rat) or vehicle and were killed 2 h later. M. fermentans caused a significant depletion of corticotropin releasing hormone (CRH-41) content in the median eminence (ME), and elevation of serum ACTH and corticosterone (CS) levels, compared to control levels. Pretreatment with dexamethasone (DEX, 40 micrograms/kg) markedly inhibited M. fermentans-induced depletion of ME CRH-41 and the increase in serum ACTH and CS. Injection of the type II corticosteroid receptor antagonist RU-38486, but not the type 1 antagonist RU-28318, enhanced the adrenocortical response and completely abolished the inhibitory effect of DEX following M. fermentans. Injection of the catecholamine neurotoxin 6-hydroxydopamine into the ventral noradrenergic bundle, which significantly depleted hypothalamic norepinephrine content, or i.c.v. injection of the specific alpha 1-adrenergic receptor antagonist prazosin failed to affect the adrenocortical response to M. fermentans. In contrast, these agents markedly inhibited the adrenocortical response following i.c.v. injection of interleukin-1. I.c.v. administration of M. fermentans caused a significant elevation of hypothalamic levels of tumor necrosis factor-alpha (TNF alpha), determined by both bioassay and immunoassay. In rats treated with pentoxifylline, an inhibitor of TNF alpha synthesis, the adrenocortical response to M. fermentans was markedly inhibited. These findings suggest that: (1) M. fermentans-induced activation of the pituitary-adrenal axis, and the inhibitory effect of DEX on this response, are mediated by a reduction of CRH-41 release from the ME. (2) The feedback exerted by glucocorticoids is mediated by type II corticosteroid receptors. (3) In contrast to the adrenocortical response to interleukin-1 beta, the central noradrenergic system does not have an important role in mediating the adrenocortical response to M. fermentans. (4) Hypothalamic TNF alpha production is probably involved in mediating the adrenocortical activation following M. fermentans.

Effect of glucocorticoids on the adrenocortical axis responses to electrical stimulation of the amygdala and the ventral noradrenergic bundle

In the present study we examined the negative feedback effect of exogenous and endogenous glucocorticoids (GC) on the responses of the hypothalamo-pituitary-adrenocortical (HPA) axis to electrical stimulation of the central amygdaloid nucleus (AMG) and the ventral noradrenergic bundle (VNAB). Injection of dexamethasone (DEX 5-50 microg/kg BW) 3.5 h prior to the electrical stimuli inhibited the serum ACTH and corticosterone (CS) responses in a dose dependent manner. At a dose of 50 microg/kg BW DEX, the stress induced responses was completely abolished. Pretreatment with a subcutaneous injection of corticosteroid type II receptor antagonist (RU-38486) 30 mg/kg BW, enhanced the ACTH and CS responses to both stimuli. In contrast, the type I receptor antagonist (RU-28381) did not affect neither the responses to both stimuli nor the inhibitory effect exerted by DEX. Electrical stimulation of both the AMG and VNAB caused a significant depletion of CRF-41 content of the median eminence (ME). Pretreatment with DEX (50 microg/kg BW) inhibited the electrical stimuli-induced depletion of ME CRH-41. These results suggest that: (1) the HPA axis responses to electrical stimuli of the AMG and the VNAB are sensitive to the negative feedback of GC; (2) the feedback effect exerted by GC is mediated by type II GC receptors; (3) CRH-41 released from the ME plays a dynamic role in mediating pituitary-adrenocortical responses to the electrical stimuli; (4) the inhibitory effect of exogenous DEX is mediated by a reduction of CRF-41 release from the ME.

Intracerebral administration of Mycoplasma fermentans produces sickness behavior: role of prostaglandins

Mycoplasmas are small microorganisms, which cause various diseases in animals and in humans, activate the immune system, and induce the release of various cytokines. Some of the effects of mycoplasmas are mediated by the CNS. Moreover, Mycoplasma fermentans (MF) has recently been found in the brain, as well as other tissues of some AIDS patients, who usually display severe neurobehavioral disturbances. The present study was designed to examine the behavioral effects of central administration of MF, and the role of prostaglandins in mediating these effects. In one set of experiments, rats were injected intracerebroventricularly (i.c.v.) with either saline or a dose of MF (5.1-36 microg per rat), and several behavioral parameters were measured. In addition, body temperature and locomotor activity were continuously monitored by a biotelemetric system. MF induced a significant elevation in body temperature and suppression of motor activity levels. MF also significantly reduced the time spent in social exploration, decreased locomotor and exploratory activity in the open field test, suppressed the consumption of food and saccharine solution, and reduced body weight. In a second set of experiments, i.c.v. administration of MF (7.2 microg) was found to produce a significant increase in the production of prostaglandin E2 (PGE2) in hypothalamic, hippocampal, and cortical tissues. This effect was blocked by indomethacin, a prostaglandin synthesis inhibitor. Indomethacin also attenuated the effects of MF on body temperature, motor activity and body weight, suggesting the involvement of prostaglandins in mediating some of the effects of MF. Together, these findings suggest that the presence of MF in the brain may be responsible for some of the neurobehavioral abnormalities in HIV-infected patients.

Involvement of amygdalar alpha adrenoceptors in hypothalamo-pituitary-adrenocortical responses

We have previously demonstrated that the facilitatory effect of the amygdala on the hypothalamo-pituitary-adrenocortical (HPA) axis responses to photic stimulation depends on the presence of norepinephrine (NE) in this region. In the present study we investigated the effect of alpha 1- and beta-adrenoceptor blockers, injected into the central amygdala nucleus, on the HPA responses. In intact freely moving rats, short photic stimulation caused depletion of CRH-41 from the median eminence, due to its release into the portal circulation and a rise in serum ACTH and corticosterone levels. This effect was markedly inhibited by injection of prazosin, an alpha 1-adrenoceptor blocker, but atenolol, a beta 1 blocker, had no effect. These data further indicate that amygdala NE plays a role in the activation of the HPA axis following neural stimuli and that this effect is mediated by alpha 1-adrenoceptors in the central amygdala.

Effects of bacterial endotoxin on the glucocorticoid feedback regulation of adrenocortical response to stress

Previous studies have shown that LPS and cytokines modulate the binding of glucocorticoids (GCs) in the CNS, and therefore may affect the negative feedback exerted by GCs. In this study, we investigated the effect of lipopolysaccharide (LPS) on the inhibitory action of GCs upon the adrenocortical response to a neural stressful stimulus. Male rats were treated with either LPS (50 micrograms/kg) or saline for 5 consecutive days. Two days later, the LPS- and saline-treated rats were injected intraperitoneally with either dexamethasone (20 micrograms/kg) or saline and sacrificed 3.5 h later, after exposure to acute stressful photic stimulation. In saline-pretreated rats, photic stimulation caused a 5-fold increase in serum corticosterone levels compared to basal levels, and pretreatment with dexamethasone completely abolished this response. In LPS-pretreated rats, corticosterone levels following photic stimulation increased 20-fold, and dexamethasone was ineffective. Additional experiments were conducted to examine whether the impairment in the negative feedback was specific to the prolonged LPS treatment, rather than to LPS-induced hypersecretion of GCs. In groups of rats which were exposed to either daily acoustic stress or daily administration of corticosterone (5 mg, twice daily) for 5 days, the pattern of corticosterone secretion mimicked the corticosterone secretion induced by LPS. In these groups, the adrenocortical response to acute photic stimulation and the effect of dexamethasone were similar to saline-pretreated controls. These results suggest that LPS impairs the negative feedback of either endogenous or exogenous GC upon the adrenocortical response to stress. This finding may be relevant to the enhanced adrenocortical activity associated with sepsis and major depression.

Rescue of HSV-1 neurovirulence is associated with induction of brain interleukin-1 expression, prostaglandin synthesis and neuroendocrine responses

Several HSV-1 neurovirulence genes have been mapped but the mechanisms by which they affect host-virus interactions are not known. We have previously mapped HSV-1 neurovirulence to the UL53 gene region of the viral DNA by transfer of this gene from the neurovirulent R-19 strain to the non-neurovirulent R-15 strain in the generation of the p-71 recombinant, in which neurovirulence was rescued. In the present study we inoculated these strains into the paraventricular nucleus (PVN) of the hypothalamus of rats. We examined: (1) Clinical course of encephalitis. (2) Hypothalamic-pituitary-adrenocortical (HPA) axis function. (3) Brain cytokine gene mRNA expression and prostaglandin E2 (PGE2) production. (4) The relation of these parameters to viral replication and to cellular inflammation. In R-15 infected rats no signs of disease were observed. There was a temporary inflammatory reaction and IL-1 beta transcription in the PVN area. The function of the HPA axis was similar to control rats. Only slight increase in brain PGE2 production was found. In R-19 and p-71 infected rats, overt clinical signs of encephalitis and cellular inflammation in the PVN area were observed within 3 days post-infection (p.i). All rats died between 4-7 days p.i. These strains induced IL-1 beta transcription in the hypothalamus as well as in extra-hypothalamic brain regions in which no cellular inflammation was found. Basal serum ACTH and' CS were markedly elevated and hypothalamic CRF-41 content was significantly reduced as compared to R-15 infected rats. Both strains markedly increased brain PGE2 production. HSV-1 brain titers at 3 days p.i. were 100-fold lower than the inoculum titer although clinical signs of encephalitis were prominent. The results suggest that rescue of HSV-1 neurovirulence by the UL53 gene region of the viral genome is associated with enhancement of viral-induced brain IL-1 beta gene expression, increased brain PGE2 synthesis and hypersecretion of HPA axis hormones. Viral-induced brain derived cytokines and prostaglandins may contribute to the clinical syndrome of acute herpetic encephalitis in particular at early stages of the disease when virus load in the brain is low and cellular infiltrates are not widespread.

Adrenocortical activation by herpes virus: involvement of IL-1 beta and central noradrenergic system

We investigated the involvement of brain cytokines and central monoamines in mediating the effect of the neurotropic herpes simplex virus-1 (HSV-1) on adrenocortical activity in rats. Corneal inoculation with a neurovirulent HSV-1 strain, but not with an avirulent strain, induced interleukin-1 beta (IL-1 beta) gene expression mainly in the pons and hypothalamus, and caused an elevation in serum corticosterone levels. Infectious virus was isolated in low titres only from the trigeminal ganglia and pons. Viral DNA was detected by PCR in these tissues and in other brain regions. Virus-induced adrenocortical activation was abolished in rats in which hypothalamic norepinephrine (NE) was depleted by 6-hydroxydopamine. Depletion of hypothalamic serotonin by 5,7-dihydroxytryptamine did not prevent adrenocortical activation. These results suggest that central IL-1 and NE are involved in HSV-1 induced adrenocortical activation.

Norepinephrine depletion in the amygdala inhibits CRF-41, ACTH, and corticosterone responses following photic simulation

The effects of amygdaloid norepinephrine depletion by 6-hydroxydopamine on changes in corticotropin releasing factor-41 (CRF-41) and serum adrenocorticotropic hormone (ACTH) and corticosterone levels, following neural stimuli were investigated. In intact animals, photic or acoustic stimulation caused CRF-41 depletion from the median eminence and a rise in serum ACTH and corticosterone levels. In rats with amygdalar norepinephrine depletion there were no changes in basal CRF-41, ACTH, or corticosterone levels. However, the above responses of the hypothalamo-pituitary adrenocortical axis were blocked following photic, but not acoustic, stimulation. These results indicate that the facilitatory role of the amygdala on the above responses following photic stimulation depends on the presence of norepinephrine in this region.

The role of limbic structures in the modulation of ACTH responses following adrenalectomy

The role of the HIPP, DF, and the lateral SPT as well as of the central AMG nucleus in ACTH hypersecretion following Adex, was studied in male rats. In animals with bilateral dorsal hippocampectomy, DF section, or SPT lesions there was a much greater increase in ACTH hypersecretion when compared to Adex alone. Implants of CS in the paraventricular nucleus of the hypothalamus prevented the rise in serum ACTH following Adex, and this effect was reversed by hippocampectomy. Bilateral lesions in the AMG prevented the Adex-induced rise of serum ACTH. These results indicate that the dorsal HIPP and its efferent pathways to the hypothalamus have normally an inhibitory effect on Adex-induced ACTH secretion. Their removal permits an elevated ACTH hypersecretion as well as attenuation of the CS feedback effect. The central AMG nucleus, which has a facilitatory effect on the hypothalamopituitary-adrenocortical axis, can also modulate ACTH secretion following Adex.

Effects of HSV-1, a neurotropic virus, on the hypothalamic-pituitary-adrenocortical axis in rats

It is well established that the hypothalamic-pituitary-adrenocortical (HPA) axis is activated during systemic viral diseases. In this study we examined the effects of a neurotropic virus, herpes simplex virus type 1 (HSV-1), on the HPA axis in male rats. Following corneal inoculation with HSV-1, the virus invaded the nervous system and replicated in the brainstem without clinical signs of disease. During this asymptomatic brainstem infection with HSV-1, significant changes were found in the function of the HPA axis: On days 3, 7 and 14 post-infection (p.i.) basal ACTH and corticosterone (CS) levels were markedly elevated, and photic stressful stimulation failed to further increase the levels of these hormones. In addition, the elevated basal serum levels of ACTH and CS could not be suppressed by pretreatment with dexamethasone. The content of CRF-41 in the paraventricular nucleus of the hypothalamus and in the median eminence measured at 6 days p.i. was similar to that of vehicle inoculated rats. By 4 weeks p.i. the basal levels of ACTH and CS returned to normal and these animals responded to photic stimulation and dexamethasone similar to vehicle inoculated rats. Systemic (intraperitoneal) inoculation of HSV-1 did not induce any changes in the HPA axis responses. We therefore suggest that asymptomatic acute infection of the brainstem with HSV-1 may affect brain regions involved in the regulation of the HPA axis, and that those effects are mediated centrally and not by a systemic mechanism.

The effect of the adrenocortical axis upon recovery from closed head injury

Fragments and analogs of the hormone ACTH were previously shown to have beneficial effect on the outcome of head injury, while elevated levels of corticosterone (CS) exacerbate it. In the present study we investigated the role of the hypothalamo-pituitary-adrenal (HPA) axis in the pathophysiology of closed head injury (CHI). CHI was produced in ether-anesthetized rats by a calibrated weight-drop device. After evaluating the functional status according to a set of criteria, at 1 and 24 h, the rats were sacrificed and cortical tissue was removed to determine its water content. CHI was also produced in rats that underwent surgical procedures to remove their adrenal gland (ADEX) or the pituitary (HypoX), thus altering the levels of their circulating HPA hormones. Given after CHI, to rats with intact HPA axis, ACTH reduced edema and improved recovery. ADEX rats (6 days postsurgery) had 10-fold higher levels of plasma ACTH. ADEX rats subjected to CHI showed improved functional outcome (p = 0.008) and reduced edema (p = 0.02). We then produced CHI in three groups of rats: HypoX (15 days postsurgery), HypoX treated with ACTH, and controls. In HypoX rats, CHI resulted in increased mortality (35% vs 0) and edema in the surviving rats, and a slower recovery, as compared with the control. Mortality was prevented, edema slightly reduced, and recovery significantly improved after administration of 1-24-ACTH to HypoX rats with CHI. Our results suggest that ACTH has a cerebroprotective effect on the outcome of CHI.

Cellular nuclear binding and retention of glucocorticoids in rat lymphoid cells: effect of long-term adrenalectomy

In the present study we have shown for the first time that lymphocytes from the spleen, thymus and mesenteric lymph nodes can specifically bind and retain 3H-dexamethasone in the nuclear fraction. The use of the specific corticosteroid receptor antagonists, RU28362 and RU38486, for the displacement of labeled dexamethasone revealed that binding was mainly of type-II glucocorticoids receptors. In lymphocytes obtained from mesenteric lymph nodes, binding was significantly higher than in cells obtained from spleen and thymus. Long-term adrenalectomy (up to 30 days), which markedly elevated serum ACTH, caused a time-dependent increase in binding in all lymphoid cells. No increase in binding was found in lymphocytes obtained from rats hypophysectomized for 15 days, in which neither serum ACTH nor corticosterone could be measured. These results suggest that the cellular nuclear binding in lymphocytes may be regulated by a pituitary factor.