A feasibility study of a novel low-level light therapy for digital ulcers in systemic sclerosis.

BACKGROUND: Locally acting, well-tolerated treatments for systemic sclerosis (SSc) digital ulcers (DUs) are needed. OBJECTIVES: Our primary aim was to investigate the safety, feasibility, and tolerability of a novel low-level light therapy (LTTT). A secondary aim was to tentatively assess efficacy. METHODS: A custom-built device comprising infrared (850 nm), red (660 nm), and violet (405 nm) LEDs was utilized. DUs were irradiated with 10 J/cm2 twice weekly for 3 weeks, with follow-up at weeks 4 and 8. Any safety concerns were documented. Patient opinion on time to deliver, feasibility, and pain visual analogue score (VAS; 0-100, 100 most severe) was collected. Patient and clinician DU global assessment VAS were documented. DUs were evaluated by laser Doppler perfusion imaging pre- and post-irradiation. RESULTS: In all, 14 DUs in eight patients received a total of 46 light exposures, with no safety concerns. All patients considered LTTT 'took just the right amount of time' and was 'feasible', with a low associated mean pain VAS of 1.6 (SD: 5.2). Patient and clinician global DC VAS improved during the study (mean change: -7.1 and -5.2, respectively, both p < .001). DU perfusion significantly increased post-irradiation. CONCLUSIONS: LTTT for DUs is safe, feasible, and well tolerated. There was an early tentative suggestion of treatment efficacy.

The melanin-concentrating hormone (MCH) system in an animal model of depression-like behavior.

Selective breeding for divergence in locomotion in a novel environment (bHR, bred High-Responder; bLR, bred Low-Responder) correlates with stress-reactivity, spontaneous anxiety-like behaviors and predicts vulnerability in a rodent model of depression. Identifying genetic factors that may account for such vulnerability are key determinants not only for the illness outcome but also for the development of better-tailored treatment options. Melanin-concentrating hormone (MCH) is a neuropeptide that exhibits some of the hallmarks of a regulator of affective states. The aim of this study was to ascertain the role of the MCH system in depression-like behaviors in bHR vs. bLR rats. bLR rats showed a 44% increase in hypothalamic pMCH mRNA and a 14% decrease in hippocampal CA1 MCH1R mRNA when compared to bHR rats. Interestingly, the amount of time that rats spent immobile in the FST (depressive-like behavior) correlated positively with the amount of hypothalamic pMCH mRNA and negatively with that of hippocampal CA1 MCH1R. The results indicate that the bLR-bHR is a useful rat model to investigate individual basal genetic differences that participate in the monitoring of emotional responsiveness (i.e., depression- and anxiety-like behaviors). They also point to the MCH system (i.e., chronically higher pMCH expression and consequently receptor down-regulation) as a candidate biomarker for the severity of depressive-like behavior. The data indicate that MCH1R participates in the modulation of depression-like behavior through a process that involves the CA1 region of the hippocampus, supporting the possible use of MCH1R antagonists in the treatment of depression.

A food predictive cue must be attributed with incentive salience for it to induce c-fos mRNA expression in cortico-striatal-thalamic brain regions.

Cues associated with rewards acquire the ability to engage the same brain systems as rewards themselves. However, reward cues have multiple properties. For example, they not only act as predictors of reward capable of evoking conditional responses (CRs), but they may also acquire incentive motivational properties. As incentive stimuli they can evoke complex emotional and motivational states. Here we sought to determine whether the predictive value of a reward cue is sufficient to engage brain reward systems, or whether the cue must also be attributed with incentive salience. We took advantage of the fact that there are large individual differences in the extent to which reward cues are attributed with incentive salience. When a cue (conditional stimulus, CS) is paired with delivery of food (unconditional stimulus, US), the cue acquires the ability to evoke a CR in all rats; that is, it is equally predictive and supports learning the CS-US association in all. However, only in a subset of rats is the cue attributed with incentive salience, becoming an attractive and desirable incentive stimulus. We used in situ hybridization histochemistry to quantify the ability of a food cue to induce c-fos mRNA expression in rats that varied in the extent to which they attributed incentive salience to the cue. We found that a food cue induced c-fos mRNA in the orbitofrontal cortex, striatum (caudate and nucleus accumbens), thalamus (paraventricular, intermediodorsal and central medial nuclei), and lateral habenula, only in rats that attributed incentive salience to the cue. Furthermore, patterns of "connectivity" between these brain regions differed markedly between rats that did or did not attribute incentive salience to the food cue. These data suggest that the predictive value of a reward cue is not sufficient to engage brain reward systems-the cue must also be attributed with incentive salience.

Radiological implications of the use of uranium in vaseline glass.

Uranium oxides have been used as colourants in glassware since the 19th century and this type of glass is commonly referred to as vaseline glass. There are many collectors of vaseline glass in the UK who obtain pieces from the UK antiques market or from abroad. Dose rate measurements were made for a number of items of vaseline glass, and the uranium content of one item was measured. Potential doses to collectors were considered, along with implications for trade and transport due to the uranium content of the glassware. It was concluded that generally items of vaseline glass could give rise to low skin doses from beta radiation, though frequent wearing of necklaces made from vaseline glass may lead to doses in excess of the HPA (Health Protection Agency) dose criterion for consumer products that are not related to safety. Registration under the Radioactive Substances Act will not be required and almost all items of vaseline glass should be suitable for sending through the Royal Mail. For those items not accepted by Royal Mail, it is understood that the transport regulations for radioactive materials would not apply.

Pre-clinical evaluation of a new orally-active CCK-2R antagonist, Z-360, in gastrointestinal cancer models.

BACKGROUND: Gastrin has a role in gastrointestinal (GI) malignancy. This study provides pre-clinical evaluation of a novel, orally-active gastrin/cholecystokinin-2 receptor (CCK-2R) antagonist, Z-360. METHODS: (125)I gastrin-17 (G17) displacement and G17-stimulated calcium assays were used in classical CCK-2R-transfected cell lines. Akt phosphorylation was assessed by Western blotting. Z-360 efficacy in vivo was evaluated in three human xenograft models, and microvessel density and apoptosis in these models were investigated by immunohistochemistry. RESULTS: Z-360 inhibited (125)I G17 binding to cells expressing CCK-2R, and G17-stimulated signalling. Reduced Akt phosphorylation in an oesophageal cell-line treated with Z-360 was reversed by co-treatment with G17. Z-360 increased survival in a gastric ascites model (p=0.011) and decreased tumour growth in a hepatic metastasis model (81%, p=0.02). In an orthotopic pancreatic model, Z-360 combined with gemcitabine decreased final tumour weight compared to single agents (84%, p=0.002) and there was increased apoptosis and decreased microvessel density in ex vivo tumour tissue. CONCLUSIONS: These results show that the orally-active CCK-2R antagonist, Z-360 has high sub-nM affinity for classical CCK-2R, is well tolerated in vivo and exerts an anti-tumour effect.

Analysis of 5-HT6 and 5-HT7 receptor gene expression in rats showing differences in novelty-seeking behavior.

Sensation-seeking is a human personality trait associated with a greater propensity to use psychoactive substances. A rat model showing face validity of this human trait has been developed. The model is based on the variety of behavioral responses that rats exhibit in a novel and inescapable environment, with some animals (high-responders, HR) being highly active, and others (low-responders, LR) showing less exploration. More active rats (HR) also show increased drug-taking and decreased anxiety-like behavior. There is evidence that response to novelty may rely on differential 5-HT-mediated neurotransmission. This research focuses on the recently discovered 5-HT6 and 5-HT7 receptors which share affinity for neuroleptic drugs and hallucinogens. To date, emerging evidence suggests that 5-HT6 and 5-HT7 may be involved in cognition and mood regulation, respectively. To further our knowledge of their behavioral attributes, we compared patterns of gene expression for these receptors in the brains of HR and LR rats. As a control, gene expression for the 5-HT3 receptor was investigated because its contribution to anxiety and addiction is only weakly demonstrated. Transcript levels for 5-HT6 in the olfactory tubercle inversely correlated with the level of locomotion in a novel environment. Phenotype differences in mRNA signal for 5-HT6 showed a complex pattern in the dentate gyrus. LR rats were statistically higher in the most anterior region of the dentate gyrus, while HR rats were higher in median areas of the dentate gyrus. Levels of 5-HT7 transcript in HR rats were significantly lower than LR rats in pivotal areas for information trafficking, such as thalamo-cortical projection areas and dorsal hippocampus. By contrast, phenotype differences in 5-HT3 expression were not found in areas of the limbic cortex and mesolimbic system. Taken together, these results provide new insight into the potential contribution of 5-HT to novelty-seeking behavior and associated behaviors such as substance abuse.

Daphnia behavioural responses to taste and odour compounds: ecological significance and application as an inline treatment plant monitoring tool.

Continuous monitoring of volatile organic compounds (VOC) in raw water is highly desirable for taste and odour management, but in most treatment plants this capacity is lacking. We used a bbe Daphnia toximeter installed in the Zurich water treatment plant to determine if Daphnia magna could be used to monitor odour compounds in source-water. Trace levels of two widely distributed biogenic VOCs in freshwater: P-cyclocitral and 2(E),4(E),7(Z)-decatrienal were added to the raw water inflow to chambers containing test animals and their behaviour was recorded using a high resolution camera. We observed that each compound elicited a marked short-term increase in Daphnia swimming velocity, but the effect was brief and an acclimation to the compounds was observed after a time period or with repeated additions. The results demonstrate that the toximeter has considerable potential as a tool to monitor certain VOCs in water, and that Daphnia perceive and react to 2(E),4(E),7(Z)-decatrienal and P-cyclocitral at concentrations between 2.5 and 25 microM.

Odourous algal-derived alkenes: differences in stability and treatment responses in drinking water.

Drinking water supplies are often impacted by taste and odour (T/O) episodes caused by algal volatile organic compounds (AVOCs) from algal blooms. Treatment and control of these events is important to utility operators, as customer confidence in the safety of public drinking water supplies is based primarily on their palatability and odour. To manage T/O outbreaks successfully, knowledge about treatment responses of AVOCs and anticipation of their outbreaks are thus of major importance to the water industry. The Glenmore Reservoir and water treatment plant (GWTP) supplies drinking water to over 50% of the ca. 1 million consumers in Calgary (Alberta). Despite low nutrients and high raw water quality, the reservoir experiences periodic outbreaks of fishy/floral T/O, caused by chrysophytes and diatoms (Uroglena americana, Dinobryon spp., Synura petersenii, Asterionella formosa). These odours are produced by the unsaturated C7-C10 alkenes 2,4-heptadienal, 2,4,7-octatriene, 2,4-decadienal and 2,4,7-decatrienal, generated during from the enzymatic breakdown of algal polyunsaturated fatty acids (PUFAs). The formation, persistence and stability of these compounds in both the raw water and treatment plant is not well understood.

Relation between the hypothalamic-pituitary-thyroid (HPT) axis and the hypothalamic-pituitary-adrenal (HPA) axis during repeated stress.

Previous work has indicated that acute and repeated stress can alter thyroid hormone secretion. Corticosterone, the end product of hypothalamic-pituitary-adrenal (HPA) axis activation and strongly regulated by stress, has been suggested to play a role in hypothalamic-pituitary-thyroid (HPT) axis regulation. In the current study, we sought to further characterize HPT axis activity after repeated exposure to inescapable foot-shock stress (FS), and to examine changes in proposed regulators of the HPT axis, including plasma corticosterone and hypothalamic arcuate nucleus agouti-related protein (AGRP) mRNA levels. Adult male Sprague-Dawley rats were subjected to one daily session of inescapable FS for 14 days. Plasma corticosterone levels were determined during and after the stress on days 1 and 14. Animals were killed on day 15, and trunk blood and brains were collected for measurement of hormone and mRNA levels. Repeated exposure to FS led to a significant decrease in serum levels of 3,5,3'-triiodothyronine (T3) and 3,5,3',5'-tetraiodothyronine (T4). Stress-induced plasma corticosterone levels were not altered by repeated exposure to the stress. Despite the decrease in peripheral hormone levels, thyrotropin-releasing hormone (TRH) mRNA levels within the paraventricular nucleus of the hypothalamus were not altered by the stress paradigm. Arcuate nucleus AGRP mRNA levels were significantly increased in the animals exposed to repeated FS. Additionally, we noted significant correlations between stress-induced plasma corticosterone levels and components of the HPT axis, including TRH mRNA levels and free T4 levels. Additionally, there was a significant correlation between AGRP mRNA levels and total T3 levels. Changes in body weight were also correlated with peripheral corticosterone and TRH mRNA levels. These results suggest that repeated exposure to mild-electric foot-shock causes a decrease in peripheral thyroid hormone levels, and that components of the HPA axis and hypothalamic AGRP may be involved in stress regulation of the HPT.

Regulatory mechanisms of corticotropin-releasing hormone and vasopressin gene expression in the hypothalamus.

Tuberoinfundibular corticotropin-releasing hormone (CRH) neurones are the principal regulators of the hypothalamic-pituitary-adrenal (HPA)-axis. Vasopressin is primarily a neurohypophysial hormone, produced in magnocellular neurones of the hypothalamic paraventricular and supraoptic nuclei, but parvocellular CRH neurones also coexpress vasopressin, which acts as a second 'releasing factor' for adrenocorticotropic hormone along with CRH. All stress inputs converge on these hypothalamic neuroendocrine neurones, and the input signals are integrated to determine the output secretion of CRH and vasopressin. Aminergic, cholinergic, GABAergic, glutamatergic and a number of peptidergic inputs have all been implicated in the regulation of CRH/vasopressin neurones. Glucocorticoids inhibit the HPA-axis activity by negative feedback. Interleukin-1 stimulates CRH and vasopressin gene expression, and is implicated in immune-neuroendocrine regulation. cAMP-response element-binding protein phosphorylation may mediate transcriptional activation of both CRH and vasopressin genes, but the roles of AP-1 and other transcription factors remain controversial. Expression profiles of the CRH and vasopressin genes are not uniform after stress exposure, and the vasopressin gene appears to be more sensitive to glucocorticoid suppression.

Effect of dietary GLA+/-tamoxifen on the growth, ER expression and fatty acid profile of ER positive human breast cancer xenografts.

Gamma linolenic acid (GLA) possesses a number of selective anti-tumour properties including modulation of steroid receptor structure and function. We have investigated the effect of dietary GLA on the growth, oestrogen receptor (ER) expression and fatty acid profile of ER+ve human breast cancer xenografts. Experimental diets A, B, C, D were commenced after subcutaneous implantation of 40 female nude mice with the MCF-7 B1M cell line (Group A = control diet: B = control diet + GLA supplement: C = control diet + tamoxifen: D = control diet + GLA + tamoxifen; 10 mice/group). The mice were terminated when tumour cross-sectional area reached 250 mm(2). ER H-scores were assessed by immunohistochemical assay and fatty acid profiles by gas-liquid chromatography of termination tumour samples. Groups C and D displayed significantly slower tumour growth (p =.0002, p =.0006) with trend for slower growth in B (p =.065) compared to control Group A. ER was significantly reduced in all groups compared to A (p <.0001) with Group D (combined therapy) displaying markedly lower ER expression than with either therapy alone (p =.0002). There were significantly raised levels of tumour GLA and metabolites in the two groups (B and D) receiving GLA (p <.0001). This xenograft model of ER+ve breast cancer has demonstrated significantly lower tumour ER expression in those groups receiving GLA, an effect which appears to be additive to the reduced ER expression resulting from tamoxifen alone. The effects of GLA on ER function and the possibility of synergistic inhibitory action of GLA with tamoxifen via enhanced down-regulation of the ER pathway require further investigation.

Effect of hydrocortisone on the pituitary response to growth hormone releasing hormone.

RATIONALE: In depression, the growth hormone (GH) response to clonidine and L-tryptophan (L-TRP) is reduced, suggesting reduced alpha2-adrenergic and serotonin (5-HT)1A receptor function. Pretreatment with hydrocortisone (100 mg, orally 11 h before) also blunts the GH response to L-TRP. This effect may be mediated at the hypothalamic level via reduced 5-HT1A receptor function or at the pituitary level, either by a direct effect on somatotrope cells or via enhanced insulin-like growth factor-1 (IGF-1) or somatostatin (SS) release. OBJECTIVES: To examine the effects of acute and chronic exposure to hydrocortisone on baseline and stimulated GH release from the pituitary. METHODS: Twelve healthy male volunteers received pretreatment with acute hydrocortisone (100 mg, 11 h before), chronic hydrocortisone (20 mg twice a day for 1 week) and placebo in a double blind, balanced order, crossover design. Serial measurements of plasma GH, IGF-1 and thyroid stimulating hormone (TSH) levels were made at baseline and following intravenous administration of 1 mcg/kg GHRH. RESULTS: The GH response to growth hormone releasing hormone (GHRH) was significantly blunted by pretreatment with both acute and chronic hydrocortisone. Baseline IGF-1 levels were significantly lower at baseline after chronic hydrocortisone compared with placebo. Baseline TSH levels were significantly lower after acute hydrocortisone compared with placebo, suggesting an increase in somatostatin levels. CONCLUSIONS: These data suggest that hydrocortisone acts at the pituitary level to reduce GH release. The TSH and IGF-1 data support the hypothesis that hydrocortisone reduces GH release by enhancing somatostatin and IGF-1 release.

Soy phytoestrogens improve radial arm maze performance in ovariectomized retired breeder rats and do not attenuate benefits of 17beta-estradiol treatment.

OBJECTIVE: Soy phytoestrogens (SPEs) seem to have beneficial effects on the cardiovascular system with no adverse effects on the breast and uterus. Our objective was to examine the effects of oral estradiol alone, soy protein with phytoestrogens alone, and combinations of estradiol and SPEs on working memory of ovariectomized retired breeder female rats using the radial arm maze test. DESIGN: Eighty-four bilaterally ovariectomized retired breeder female rats were randomized into 12 groups to examine the effects of chronic treatment (10 months) with oral micronized estradiol (0, 0.5, 1, and 2 mg/1,800 Cal), SPEs (0, 72, and 144 mg/1,800 Cal), and all combinations of these doses of estradiol and SPEs on working memory. RESULTS: Oral administration of estradiol or SPEs resulted in a dose-dependent improvement in the performance of the radial arm maze tests. In addition, at each of the three doses of oral micronized estradiol tested, the performance of the radial arm tests was not significantly different in the presence or absence of SPEs. CONCLUSIONS: Our data suggest that SPEs may function as estrogen agonists in improving working memory in the ovariectomized retired breeder female rats and that SPEs do not antagonize the beneficial effects of estradiol on the working memory of these rats. No additional benefits on the radial arm maze test performance were observed with the tested combinations of estradiol and SPEs.

Marijuana and medicine: assessing the science base: a summary of the 1999 Institute of Medicine report.

In response to public pressure to allow the medical use of marijuana, the Office of National Drug Control Policy, Washington, DC, funded a study by the Institute of Medicine evaluating the scientific evidence for benefits and risks of using marijuana as a medicine. The report used scientific reviews, public hearings, and reports from other agencies, and was evaluated by knowledgeable advisors and reviewers. It called for heavier investment in research on the biology of cannabinoid systems, careful clinical studies of cannabinoids in clinical syndromes, analysis of cannabinoids' psychological effects on symptoms, and evaluations of the health consequences of heavy marijuana use; recommends against the use of smoked marijuana in medicine and for the development of a medical cannabinoid inhaler; and recommends that compassionate use of marijuana be considered under carefully reviewed protocols. Finally, the report evaluates the abuse potential, tolerance, withdrawal, and gateway risks of medical use of cannabinoid drugs.

Differential distribution and regulation of OX1 and OX2 orexin/hypocretin receptor messenger RNA in the brain upon fasting.

To further understand the functions of the orexin/hypocretin system, we examined the expression and regulation of the orexin/hypocretin receptor (OX1R and OX2R) mRNA in the brain by using quantitative in situ hybridization. Expression of OX1R and OX2R mRNA exhibited distinct distribution patterns. Within the hypothalamus, expression for the OX1R mRNA was largely restricted in the ventromedial (VMH) and dorsomedial hypothalamic nuclei, while high levels of OX2R mRNA were contained in the paraventricular nucleus, VMH, and arcuate nucleus as well as in mammilary nuclei. In the amygdala, OX1R mRNA was expressed throughout the amygdaloid complex with robust labeling in the medial nucleus, while OX2R mRNA was only present in the posterior cortical nucleus of amygdala. High levels of OX2R mRNA were also observed in the ventral tegmental area. Moreover, both OX1R and OX2R mRNA were observed in the hippocampus, some thalamic nuclei, and subthalamic nuclei. Furthermore, we analyzed the effect of fasting on levels of OX1R and OX2R mRNA in the hypothalamic and amygdaloid subregions. After 20 h of fasting, levels of OX1R mRNA were significantly increased in the VMH and the medial division of amygdala. An initial decrease (14 h) and a subsequent increase (20 h) in OX1R mRNA levels after fasting were observed in the dorsomedial hypothalamic nucleus and lateral division of amygdala. Levels of OX2R mRNA were augmented in the arcuate nucleus, but remained unchanged in the dorsomedial hypothalamic nucleus, paraventricular hypothalamic nucleus, and amygdala following fasting. The time-dependent and region-specific regulatory patterns of OX1R and OX2R suggest that they may participate in distinct neural circuits under the condition of food deprivation.

Connections of some auditory-responsive posterior thalamic nuclei putatively involved in activation of the hypothalamo-pituitary-adrenocortical axis in response to audiogenic stress in rats: an anterograde and retrograde tract tracing study combined with Fos expression.

Prior studies in our laboratory demonstrated that part of the thalamus is necessary for activating the hypothalamo-pituitary-adrenocortical (HPA) axis in response to audiogenic stress in rats. The present studies were designed to determine how the auditory-responsive thalamic nuclei might activate the HPA axis. Both retrograde [Fluoro-Gold (FG)] and anterograde [Phasoleus vulgaris-leucoagglutinin (PHA-L) and biotinylated dextran amines (BDA)] tracers were employed to study the putative connectivity between the thalamus and the medial parvocellular region of the hypothalamic paraventricular nucleus (PAmp). In addition, rats receiving FG in the PAmp were subjected to audiogenic stress, and the distribution of both FG and the protein product of the immediate-early gene c-fos, Fos, were determined by double immunohistochemistry, to help assess putative functional links between the auditory-responsive thalamic nuclei and PAmp. The results of PAmp FG placement indicated retrogradely labeled cells in several areas, including the bed nucleus of the stria terminalis, hypothalamic regions, the supramammillary nucleus, some thalamic regions, and importantly, a few multisensory nuclei of the thalamus, including the parvicellular division of the subparafascicular and posterior intralaminar nuclei. Injections of the tracers PHA-L or BDA into these auditory-responsive posterior thalamic nuclei provided further evidence of projections to the PAmp. In addition, several forebrain areas were observed to receive moderate to heavy innervation. These areas included most of the regions described above, which, in turn, project to the PAmp. Because cells in the multisensory thalamic nuclei, hypothalamic, and forebrain areas were double labeled with FG and Fos, the results suggest that either direct projections from the thalamus to PAmp neurons, or indirect projections from the thalamus to stress-responsive forebrain areas projecting to the PAmp, might mediate activation of the HPA axis by audiogenic stress.

Distinct neurochemical populations in the rat central nucleus of the amygdala and bed nucleus of the stria terminalis: evidence for their selective activation by interleukin-1beta.

The lateral division of the central nucleus of the amygdala (CEAl) and the oval nucleus of the bed nucleus of the stria terminalis (BSTov) have been linked closely anatomically and functionally. To determine whether these regions may be subdivided further on a neurochemical basis, dual in situ hybridization was used to determine the colocalization of corticotropin-releasing hormone (CRH), enkephalin (ENK), or neurotensin (NT) with glutamic acid decarboxylase isoforms 65 and 67 [used concurrently as a marker for gamma-aminobutyric acid GABA] in these nuclei. It was found that, for both regions, each peptide invariably was localized in a GABAergic cell. Although there was a similar overlap in the distribution of NT with ENK in the BSTov and CEAl, it was observed that CRH and ENK rarely were colocalized in either nucleus. To determine whether these distinct neuronal populations could be activated differentially, male rats were given a systemic injection of interleukin-1beta (IL-1beta; 5 microg/kg, i.p.), a stimulus that results in a robust increase in c-fos mRNA expression in the BSTov and CEAl. The neurochemical identity of these activated neurons showed striking similarities between the BSTov and the CEAl; All IL-1beta-responsive cells were GABAergic, the majority of c-fos- positive cells expressed ENK mRNA (BSTov, 81%; CEAl, 94%), and some expressed NT mRNA (BSTov, 23%; CEAl, 22%), whereas very few expressed CRH mRNA (BSTov, 4%; CEAl, 1%). These data provide evidence for the existence of discrete neural circuits within the BSTov and CEAl, and the similarities in the patterns of neurochemical colocalization in these nuclei are consistent with the concept of an extended amygdala. Furthermore, these data indicate that intraperitoneal IL-1beta recruits neurochemically distinct pathways within the BSTov and CEAl, and it is suggested that this differential activation may mediate specific aspects of immune, limbic, and/or autonomic processes.

Physiological and anatomical circuitry between Agouti-related protein and leptin signaling.

Agouti-related protein (AGRP) is an orexigenic neuropeptide that acts via central melanocortin receptors, and whose messenger RNA (mRNA) levels are elevated in leptin-deficient mice. Fasting associated with a decline in circulating leptin normally causes a 15-fold elevation of hypothalamic Agrp mRNA levels but has no effect in leptin-deficient mice. Chronic hyperleptinemia associated with the tubby and Cpe(fat) mutations has no effect on Agrp mRNA levels, but short term leptin administration causes a 17% reduction of Agrp mRNA levels in nonmutant mice and a 700% reduction in leptin-deficient mice. In young nonobese animals, melanocortin receptor blockade associated with the Ay mutation causes complete resistance to leptin-induced weight loss. Dual in situ hybridization reveals that Agrp-expressing neurons in the medial portion of the arcuate nucleus constitute a subpopulation different from Pomc-expressing neurons, and that a significant proportion of Agrp-expressing neurons (10-25%) coexpresses the leptin receptor, Lepr-b. Immunocytochemistry confirms distinct locations of AGRP- and POMC-expressing cell bodies, but reveals an overlapping distribution of their terminal fields in the arcuate nucleus, the paraventricular hypothalamus, and the dorsomedial hypothalamus. These results suggest that in the fed state, AGRP is normally suppressed by leptin, and that release of this suppression during fasting leads to increased ingestive behavior.