Accelerated cell turnover 48 h after intestinal ischemia is NOTCH independent

AIM OF THE STUDY

Notch signaling plays important roles in maintaining intestinal epithelial homeostasis. When Notch signaling is blocked, proliferation ceases and epithelial cells become secretory. The purpose of the present study was to evaluate the role of Notch signaling pathway following intestinal ischemia-reperfusion (IR) injury in a rat model.

MATERIALS AND METHODS

Male Sprague-Dawley rats were randomly divided into four experimental groups: Sham-24 and Sham-48 rats underwent laparotomy and were killed 24 or 48 h later, respectively; IR-24 and IR-48 rats underwent occlusion of SMA and portal vein for 30 min followed by 24 or 48 h of reperfusion, respectively. Enterocyte proliferation and enterocyte apoptosis were determined at killing. Notch-related gene and protein expression were determined using Real Time PCR, Western blotting and immunohistochemistry 48 h followed IR.

MAIN RESULTS

IR-48 rats demonstrated significantly increased rates of cell proliferation and increased cell apoptosis in both jejunum and ileum compared to Sham rats. IR-48 rats exhibited a significant decrease in Notch-1 protein expression (Western blot) that was coincided with a significant decrease in the number of Notch-1 positive cells (immunohistochemistry) in jejunum (35% decrease, p < 0.05) and ileum (twofold decrease, p < 0.05) as well as Hes-1 positive cells in jejunum (28% decrease, p < 0.05) and ileum (31% decrease, p < 0.05) compared to Sham-48 rats.

CONCLUSIONS

Forty-eight hours following intestinal IR in rats, accelerated cell turnover was associated by inhibited Notch signaling pathway. Intestinal stem cells differentiation toward secretory progenitors rather than differentiation toward absorptive cells is important at this phase of intestinal recovery.

Antioxidant treatment ameliorates germ cell apoptosis induced by a high-dose ionizing irradiation in rats

BACKGROUND

Exposure to ionizing radiation results in cytotoxic and genotoxic effects caused mainly by the oxidative damage. In the present study, we investigated the radioprotective effect of novel antioxidant cocktail on germ cell apoptosis and spermatogenesis in rats subjected to whole body radiation (WBIR).

METHODS

Adult male rats weighing 250-270 g were divided into four groups, eight rats each. Group 1 served as untreated control, group 2 received an IP single dose of antioxidant cocktail (1 ml). Group 3 was exposed to a WBIR (6 Gy). Group 4 received antioxidant cocktail before WBIR. Rats from each group were killed after 48 h. MDA levels were measured in serum (TBARS assay). Johnsen's criteria and the number of germinal cell layers were used to categorize spermatogenesis. TUNEL assay was used to determine germ cell apoptosis. Statistical analysis was performed using one-way ANOVA test.

RESULTS

WBIR resulted in histological testicular damage (decrease in Johnsen's criteria, p < 0.05) that was accompanied by a significant increase in germ cell apoptosis, expressed as the number of apoptotic cells per 100 tubules (AI-1 apoptotic index) and the number of positive tubules per 100 tubules (AI-2 apoptotic index). Treatment with antioxidant cocktail resulted in a significant decrease in germ cell apoptosis (33% decrease in AI-1, p < 0.05 and 34% decrease in AI-2, p < 0.05) that was accompanied by an improved spermatogenesis (increase in Johnsen's criteria, p < 0.05).

CONCLUSIONS

In a rat model of WBIR, antioxidant treatment ameliorates oxidative stress-induced testicular damage, decreases germ cell apoptosis and improves spermatogenesis.

The role of intermediate filaments in maintaining integrity and function of intestinal epithelial cells after massive bowel resection in a rat

PURPOSE

Intermediate filaments (IFs) are a part of the cytoskeleton that extend throughout the cytoplasm of all cells and function in the maintenance of cell-shape by bearing tension and serving as structural components of the nuclear lamina. In normal intestine, IFs provide a tissue-specific three-dimensional scaffolding with unique context-dependent organizational features. The purpose of this study was to evaluate the role of IFs during intestinal adaptation in a rat model of short bowel syndrome (SBS).

MATERIALS AND METHODS

Male rats were divided into two groups: Sham rats underwent bowel transection and SBS rats underwent a 75% bowel resection. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined 2 weeks after operation. Illumina's Digital Gene Expression (DGE) analysis was used to determine the cytoskeleton-related gene expression profiling. IF-related genes and protein expression were determined using real-time PCR, Western blotting and immunohistochemistry.

RESULTS

Massive small bowel resection resulted in a significant increase in enterocyte proliferation and concomitant increase in cell apoptosis. From the total number of 20,000 probes, 16 cytoskeleton-related genes were investigated. Between these genes, only myosin and tubulin levels were upregulated in SBS compared to sham animals. Between IF-related genes, desmin, vimentin and lamin levels were down-regulated and keratin and neurofilament remain unchanged. The levels of TGF-β, vimentin and desmin gene and protein were down-regulated in resected rats (vs sham animals).

CONCLUSIONS

Two weeks following massive bowel resection in rats, the accelerated cell turnover was accompanied by a stimulated microfilaments and microtubules, and by inhibited intermediate filaments. Resistance to cell compression rather that maintenance of cell-shape by bearing tension are responsible for contraction, motility and postmitotic cell separation in a late stage of intestinal adaptation.

Psychiatric disorders in a cohort of individuals with Prader-Willi syndrome

BACKGROUND

Psychiatric manifestations in Prader-Willi Syndrome (PWS) are common and often are the most debilitating problem in these individuals. We present an epidemiological nation-wide survey of psychiatric diagnoses in the PWS population, based on full-range psychiatric interviews.

METHODS

We studied the distribution of psychiatric diagnoses (as opposed to a symptom-based approach) in the Israel national cohort of adolescents and adults with PWS. There was a total of 53 (32 males) ages 12 years and older. All individuals and their caretakers were interviewed using standardized psychiatric questionnaires. Demographic and clinical variables, Clinical Global Impression (CGI) score, IQ, severity of hyperphagia and quality of life (QOL) were also assessed and correlations with NPD (number of psychiatric diagnoses) calculated.

RESULTS

An overwhelming majority (89%) of the study participants had at least one psychiatric diagnosis. The most common were disruptive behavior disorders (DBD) (68%), obsessive compulsive disorder (OCD) (45%) and skin picking (35%). Individuals with DBD were at increased risk for OCD and skin picking. Psychotic disorders were found in 11%. NPD had a significant negative influence on QOL. There was no correlation between NPD and BMI, IQ, hyperphagia severity, hormonal profile or genetic subtypes.

CONCLUSIONS

Psychiatric diagnoses are very frequent in PWS and strongly influence QOL. Furthermore, characterizing the profile of psychiatric comorbidity in PWS is crucial for planning effective interventions. Precise behavioral phenotyping in PWS in combination with a well-defined genetic etiology may aid biological research linking biological correlates to behavior.

Fenofibrate reduces intestinal damage and improves intestinal recovery following intestinal ischemia-reperfusion injury in a rat

PURPOSE

Fenofibrate (FEN) is known as a nuclear receptor activator which regulates many pathophysiological processes, such as oxidative stress, inflammation, and leukocyte endothelium interactions. Recent studies have demonstrated an anti-oxidant, anti-inflammatory, and anti-ischemic role of FEN in the attenuation of ischemia-reperfusion (IR) injury in the kidney, liver, brain, and heart. The purpose of the present study was to examine the effect of FEN on intestinal recovery and enterocyte turnover after intestinal IR injury in rats.

METHODS

Male Sprague-Dawley rats were divided into four experimental groups: (1) sham rats underwent laparotomy, (2) sham-FEN rats underwent laparotomy and were treated with intraperitoneal (IP) FEN (20 mg/kg); (3) IR rats underwent occlusion of both the superior mesenteric artery and the portal vein for 30 min followed by 24 h of reperfusion, and (4) IR-FEN rats underwent IR and were treated with IP FEN immediately before abdominal closure. Intestinal structural changes, Park's injury score, enterocyte proliferation, and enterocyte apoptosis were determined 24 h following IR. The expression of Bax, Bcl-2, p-ERK, and caspase-3 in the intestinal mucosa was determined using real-time PCR, Western blot, and immunohistochemistry.

RESULTS

Treatment with FEN resulted in a significant decrease in Park's injury score in jejunum (32 %) and ileum (33 %) compared to IR animals. IR-FEN rats also demonstrated a significant increase in mucosal weight in jejunum (23 %) and ileum (22 %), mucosal DNA (38 %) and protein (65 %) in jejunum, villus height in jejunum (17 %) and ileum (21 %), and crypt depth in ileum (14 %) compared to IR animals. IR-FEN rats also experienced significant proliferation rates as well as lower apoptotic indices in jejunum and ileum which was accompanied with higher Bcl-2 levels compared to IR animals.

CONCLUSIONS

Treatment with fenofibrate prevents intestinal mucosal damage and stimulates intestinal epithelial cell turnover following intestinal IR in a rat model.

Effect of taurine on intestinal recovery following intestinal ischemia-reperfusion injury in a rat

PURPOSE

Taurine (TAU) is a sulfur-containing amino acid that is involved in a diverse array of biological and physiological functions, including bile salt conjugation, osmoregulation, membrane stabilization, calcium modulation, anti-oxidation, and immunomodulation. Several studies have established that treatment with TAU significantly protects cerebral, cardiac and testicular injury from ischemia-reperfusion (IR). The purpose of the present study was to examine the effect of TAU on intestinal recovery and enterocyte turnover after intestinal IR injury in rats.

METHODS

Male Sprague-Dawley rats were divided into four experimental groups: (1) Sham rats that underwent laparotomy, (2) Sham-TAU rats that underwent laparotomy and were treated with intraperitoneal (IP) TAU (250 mg/kg); (3) IR-rats that underwent occlusion of both superior mesenteric artery and portal vein for 30 min followed by 48 h of reperfusion, and (4) IR-TAU rats that underwent IR and were treated with IP TAU (250 mg/kg) immediately before abdominal closure. Intestinal structural changes, Park's injury score, enterocyte proliferation and enterocyte apoptosis were determined 24 h following IR. The expression of Bax, Bcl-2, p-ERK and caspase-3 in the intestinal mucosa was determined using Western blot and immunohistochemistry.

RESULTS

Treatment with TAU resulted in a significant decrease in Park's injury score compared to IR animals. IR-TAU rats also demonstrated a significant increase in mucosal weight in jejunum and ileum, villus height in jejunum and ileum and crypt depth in ileum compared to IR animals. IR-TAU rats also experienced significantly lower apoptotic indices in jejunum and ileum which was accompanied by a higher Bcl-2/Bax ratio compared to IR animals.

CONCLUSIONS

Treatment with taurine prevents gut mucosal damage and inhibits intestinal epithelial cell apoptosis following intestinal IR in a rat.

Sexual dichotomy of gonadal function in Prader-Willi syndrome from early infancy through the fourth decade

STUDY QUESTION

At what age does the type of hypogonadism, namely hypothalamic or primary gonadal defect, become established in men and women with Prader-Willi syndrome (PWS)?

SUMMARY ANSWER

The type of hypogonadism becomes established only in late adolescence and early adulthood.

WHAT IS KNOWN ALREADY

The etiology of hypogonadism in PWS is heterogeneous and the clinical expression is variable. Primary testicular failure is common in PWS men, while combinations of ovarian dysfunction and gonadotrophin deficiency are seen in women.

STUDY DESIGN, SIZE, DURATION

This is a prospective study of a cohort of 106 PWS patients followed for a mean duration of 4.5 years. Serial blood samples were obtained and assayed for gonadotrophins, inhibin B, anti-Mullerian hormone (AMH), dehydroepiandrosterone sulfate (DHEAS), testosterone (males), and estradiol (females). Results were compared with normal reference values obtained from the literature. For the purpose of this study, we defined the following age groups: infants <1 year; children 1-10 years; adolescents 11-20 years and adults >20 years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Study participants were 49 males (aged 2 months to 36 years) and 57 females (aged 1 month to 37 years) with genetically confirmed diagnoses of PWS (deletions 60, uniparental disomy 54, imprinting center defect 2) followed in the Israel national multidisciplinary PWS clinic.

MAIN RESULTS AND THE ROLE OF CHANCE

Serum LH levels were in the normal range (1.0-6.0 mIU/ml) for 7/10 adult men, and high in 3, while FSH (normal range 1.0-6.1 mIU/ml) was elevated (34.4 ± 11.5 mIU/ml) in 6 and normal (3.5 ± 1.6 mIU/ml) in 4 men. Testosterone was low (5.7 ± 3.4 nmol/l) compared with the normal range of 12.0-34.5 nmol/l in the reference population in all men >20 years. AMH showed a normal decrease with age, despite low testosterone levels. Inhibin B was normal (241 ± 105 pg/ml) in infant boys, but low or undetectable in most adult men. Hormonal profiles were more heterogeneous in women than in men. Estradiol was consistently detectable in only 7/13 adult women. Inhibin B was low or undetectable in all PWS females although occasional samples showed levels within the normal range of 15-95 pg/ml. Vaginal bleeding was reported to occur for the first time in eight women at a median age of 20 years (13-34 years), but only one had regular monthly menses. The type of hypogonadism (primary or secondary) in PWS can be determined only after age 20 years.

LIMITATIONS, REASONS FOR CAUTION

The study cohort was heterogeneous, showing variability in BMI, cognitive disability and medical treatment.

WIDER IMPLICATIONS OF THE FINDINGS

Demonstration of the natural history of reproductive hormone development in PWS suggests that androgen replacement may be indicated for most PWS boys in mid-adolescence. Recommendations for hormone replacement in PWS women need to be individually tailored, serial measurements of inhibin B should be performed, and contraception should be considered in those women who may have the potential for fertility.

Accidental injuries are more common in children with attention deficit hyperactivity disorder compared with their non-affected siblings

BACKGROUND

Accidental injuries are a leading cause of paediatric morbidity and mortality. We hypothesized that attention deficit hyperactivity disorder (ADHD), a common childhood disorder characterized by behaviours such as hyperactivity and impulsivity, is a risk factor for accidental injuries. Previous retrospective studies suggested that children with ADHD have an increased injury rate, but controlled prospective studies are lacking.

METHODS

We conducted a prospective case-control study of 29 school-aged children with ADHD and their same-sex, similarly aged, non-ADHD-affected siblings. All diagnoses were made by a paediatric neurologist according to DSM-IV criteria and the children and their parents underwent a structured psychiatric interview and a battery of complementary assessments including: Child Behavior Checklist (CBCL), ADHD Rating scale and Developmental Coordination Disorder Questionnaire (DCDQ). The parents were contacted by telephone every 3 months during a 9-month follow-up period and all injuries requiring medical attention were recorded. Incidence of injuries was compared between the pairs of siblings.

RESULTS

During the follow-up period, a total of 13 injuries in 13 children with ADHD were reported, compared with six injuries in six children from the control group (Z=-2.11, P < 0.05). ADHD severity and subtype, CBCL, DCDQ and IQ scores were not predictive of injury risk.

CONCLUSIONS

School-aged children with ADHD are at higher risk of accidental injuries than their non-ADHD siblings, regardless of ADHD subtype, co-morbid psychiatric conditions, developmental co-ordination problems and environmental/familial conditions. Awareness and adequate education of parents and caregivers of children with ADHD concerning the increased injury risks are thus warranted.

Retrieval processes in adults with ADHD: a RAVLT study

Attention-deficit hyperactivity disorder (ADHD) is associated with memory deficiencies. In the current study we compared different aspects of verbal memory using standard and constructed measures of the Rey auditory verbal learning test (RAVLT). Performance on learning and recognition measures of RAVLT was similar in both ADHD and control groups. In contrast, adults with ADHD committed more double recalls and intrusion errors, indicating inaccurate recall processes. These findings suggest that memory problems in adults with ADHD may be caused by deficient executive processes that support retrieval from memory.

Why do young women smoke? V. Role of direct and interactive effects of nicotinic cholinergic receptor gene variation on neurocognitive function

Previous work suggests that young women who smoke cigarettes regularly, or did so in the past, manifest a neurocognitive profile that is characterized by small but significant impairments of response inhibition and attention. The present study sought to determine whether variation in nicotinic cholinergic receptor (nAchR) genes impacts upon cognitive function in these domains by overall or differential effects on the performance of current, former and non-smokers. The study sample consisted of 100 female college students, current or past smokers, and 144 who had never smoked. All performed a computerized neurocognitive test battery and were genotyped for 39 single nucleotide polymorphisms in 11 nAchR genes. The results, derived from linear or logistic regression, show significant direct and interactive relationships between single nucleotide polymorphisms and haplotypes in several nAchR genes and performance on the Matching Familiar Figures Test (MFFT) Stroop test, Continuous Performance Task (CPT) and Tower of London (TOL) test. Response inhibition (MFFT, Stroop, CPT Loading Phase, TOL) was associated with variants in CHRNA2, CHRNA4, CHRNA5, CHRNA7, CHRNA9, CHRNA10, CHRNB2 and CHRNB3. Selective attention (Stroop) was associated with CHRNA4, CHRNA5, CHRNA9 and CHRNB2. Sustained attention (CPT Boring Phase) was associated with CHRNA4, CHRNA5, CHRNA7, CHRNA10 and CHRNB3. Up to 37% of the variance among the smokers and up to 47% of the variance among the non-smokers on the test measures was explained. Differences between smokers and non-smokers in neurocognitive function, putatively implicated in susceptibility to nicotine dependence, may be modulated by variants in nAchR genes, with potential implications for prevention and treatment.

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.

The EAE-associated behavioral syndrome: II. Modulation by anti-inflammatory treatments

EAE is associated with sickness behavior symptoms that are temporally correlated with inflammatory processes. To further elucidate the role of inflammatory mediators in the behavioral syndrome, EAE mice were injected daily with anti-inflammatory drugs, beginning at disease onset. Dexamethasone or interleukin-1 (IL-1) receptor antagonist or the prostaglandins synthesis inhibitor indomethacin attenuated the behavioral symptoms. Administration of the tumor necrosis-factor alpha (TNF-alpha) synthesis inhibitor pentoxifylline or targeted deletion of the type I TNF receptor had no behavioral effects whereas administration of pentoxifylline in IL-1ra-treated mice further reversed the behavioral depression. These findings demonstrate the critical involvement of pro-inflammatory cytokines and prostaglandins in the EAE-associated behavioral syndrome, and may have implications for understanding and treating the neuropsychiatric disturbances in multiple sclerosis (MS) patients.

Neuronal overexpression of "readthrough" acetylcholinesterase is associated with antisense-suppressible behavioral impairments

Molecular origin(s) of the diverse behavioral responses to anticholinesterases were explored in behaviorally impaired transgenic (Tg) FVB/N mice expressing synaptic human acetylcholinesterase (hAChE-S). Untreated hAChE-S Tg, unlike naïve FVB/N mice, presented variably intense neuronal overexpression of the alternatively spliced, stress-induced mouse "readthrough" mAChE-R mRNA. Both strains displayed similar diurnal patterns of locomotor activity that were impaired 3 days after a day-to-night switch. However, hAChE-S Tg, but not FVB/N mice responded to the circadian switch with irregular, diverse bursts of increased locomotor activity. In social recognition tests, controls displayed short-term recognition, reflected by decreased exploration of a familiar, compared to a novel juvenile conspecific as well as inverse correlation between social recognition and cortical and hippocampal AChE specific activities. In contrast, transgenics presented poor recognition, retrievable by tetrahydroaminoacridine (tacrine, 1.5 mg kg(-1)). Tacrine's effect was short-lived (24 h) suppression of the abnormal social recognition pattern in transgenics. Efficacy of antisense treatment was directly correlated with AChE-R levels and the severity of the impaired phenotype, being most apparent in transgenics presenting highly abnormal pre-treatment behavior. These findings demonstrate that neuronal AChE-R overproduction is involved in various behavioral impairments and anticholinesterase responses, and point to the antisense strategy as a potential approach for re-establishing cholinergic balance.

Experimental autoimmune encephalomyelitis-associated behavioral syndrome as a model of 'depression due to multiple sclerosis'

Many medical conditions, including inflammatory diseases such as multiple sclerosis (MS), are often accompanied by a high prevalence of depressive episodes. Inflammatory mediators, such as cytokines, were implicated in illness-associated depressive conditions, both in humans and in animals. For example, MS-associated depression (MSD) was attributed to pathophysiological processes such as immune dysregulation and cerebral inflammation. We have recently documented a depressive-like behavioral syndrome in mice with experimental autoimmune encephalomyelitis (EAE), an established model of MS. In the present paper, we discuss the similarities between the EAE-associated behavioral syndrome (EBS) and MSD, in terms of phenomenology, putative mechanisms and responsiveness to anti-depressive therapy. In particular, we show that: (1) EAE and depression are associated not only with similar behavioral symptomatology, but also with common physiological alterations, including impaired serotonergic neurotransmission, and activation of neuroendocrine (e.g., adrenocortical) and inflammatory cytokine systems; (2) the EBS precedes any neurological deficit during the initial EAE attack, as well as further exacerbations, and remits during recovery and between relapses. Similarly, in many MS patients depression precedes and accompanies the attacks and wanes during remissions; (3) females show increased susceptibility to EBS. Similarly, depression is much more prevalent in women than in men; (4) chronic treatment with the tricyclic anti-depressant imipramine reduced EAE-induced mortality, body-weight loss and behavioral suppression. Similarly, anti-depressant drugs have been used effectively in treating MSD. These findings suggest that the EBS may serve as an animal model for MSD.

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.

Behavioral aspects of experimental autoimmune encephalomyelitis

Acute inflammation is known to induce a depressive-like sickness behavior syndrome in humans and in experimental animals. In the present study, we sought to determine whether a chronic neuroautoimmune inflammation is also associated with a similar behavioral syndrome. Experimental autoimmune encephalomyelitis (EAE) was induced in SJL/J female mice by adoptive transfer of lymph node cells, and sickness behavior symptoms, including anorexia, loss of body weight, reduced social exploration, and decreased preference for sucrose solution were measured. We report that these components of sickness behavior were induced during the acute phase of the disease, and recovered in later phases. Moreover, the onset and recovery of the behavioral symptoms preceded the onset and recovery of the neurological signs, respectively. Since EAE is considered a model for multiple sclerosis (MS), it is suggested that EAF-induced behavioral changes may serve as a model for the depressive symptomatology that characterizes most MS patients.

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.

Effects of prenatal morphine exposure on NK cytotoxicity and responsiveness to LPS in rats

Prenatal exposure to opiates can adversely affect fetal development, resulting in long-term growth retardation and impairments in physiological and behavioral functions. In the present study we studied long-term effects of prenatal morphine exposure on immune functions, including the activity of natural killer (NK) cells and the febrile and behavioral responses to lipopolysaccharide (LPS). Pregnant Fischer 344 rats were given increasing doses of morphine in slow release emulsion during gestational days 12-18. Control rats were injected with vehicle and were either pair fed to morphine rats or fed ad lib. Postnatal experiments were conducted when offspring were 10-12 weeks old. Compared to both control groups, rats prenatally exposed to morphine exhibited: 1) suppressed cytotoxic activity of NK cells; 2) reduced LPS-induced fever measured by a biotelemetric system; 3) reduced hyperalgesia measured by the hot-plate test at 30 min, and augmented hypoalgesia at 2-6 h post-LPS; 4) higher open-field activity in saline-treated animals, and more pronounced suppression of activity in LPS-injected animals; 5) LPS-induced reduction of food consumption, body weight, and social exploration, which did not differ from the reduction observed in control animals. These findings indicate that prenatal exposure to morphine induces long-term impairment of host-defense mechanisms, which may render the offspring more susceptible to infectious diseases.

Different receptor mechanisms mediate the effects of endotoxin and interleukin-1 on female sexual behavior

Activation of the immune system by lipopolysaccharide (LPS) produces physiological, neuroendocrine and behavioral effects, some of which are mediated by cytokine production. We have previously shown that the cytokine interleukin-1 (IL-1) inhibits sexual behavior in female, but not male rats, while producing a comparable suppression of locomotion in both sexes. The present study examined the effects of LPS on sexual behavior and locomotion of male and female rats, and the involvement of IL-1 receptors in mediating the effects of IL-1 and LPS on females' behavior. Peripheral (i.p.) administration of LPS (50 or 250 microg/kg) significantly decreased sexual behavior in females, up to 6 h after administration, while it had no effect on male sexual behavior. However, locomotor activity, measured in the open-field test, was similarly reduced by LPS in both males and females. Pretreatment with the IL-1 receptor antagonist (IL-1ra) either i.p. (10 mg/kg) or intracerebroventricularly (i.c.v.) (50 microg/rat) did not prevent the inhibition of female sexual behavior and locomotion induced by either i.p. (50 microg/kg) or i.c.v. (200 or 400 ng/rat) administration of LPS, respectively. However, identical doses of IL-1ra significantly reversed the effects of IL-1beta, administered either i.p. (5 microg/kg) or i.c.v. (50 ng/rat), respectively. These results demonstrate that both LPS and IL-1beta produce marked inhibition of sexual behavior in female, but not in male rats. However, IL-1 receptors are not required for the effects of LPS on sexual behavior in female rats.

Administration of interleukin-1 into the hypothalamic paraventricular nucleus induces febrile and behavioral effects

Administration of interleukin-1 (IL-1) into the cerebral ventricles produces marked physiological and behavioral effects. However, the precise locations within the central nervous system that mediate these effects have not been determined. Previous studies indicated that IL-1 induces neurophysiological, neurochemical and neuroendocrine changes within the hypothalamic paraventricular nucleus (PVN). These findings suggest that the PVN is also involved in mediating the behavioral effects of IL-1. This hypothesis was tested by examining the effects of administration of IL-1beta (10 or 50 ng/rat) or saline, either intracerebroventricularly or into the PVN, on fever and several behavioral parameters. IL-1beta, administered into both locations, induced a comparable suppression of motor activity, reduction in food and saccharine consumption, and loss of body weight. The febrile response to IL-1beta, assessed by a biotelemetric system, was significantly greater following administration into the PVN than into the lateral ventricle. Additionally, IL-1 administration into adjacent thalamic locations had no febrile or behavioral effects. These findings suggest that the PVN may be one of the brain structures involved in mediating the response to IL-1.