MAB5280 Sigma-AldrichAnti-Tyrosine Hydroxylase Antibody, clone 2/40/15

Abdominal surgery inhibits food intake and induces c-Fos expression in the hypothalamic and medullary nuclei in rats. Rikkunshito (RKT), a Kampo medicine improves anorexia. We assessed the alterations in meal microstructure and c-Fos expression in brain nuclei induced by abdominal surgery and the modulation by RKT in mice. RKT or vehicle was gavaged daily for 1 week. On day 8 mice had no access to food for 6-7 h and were treated twice with RKT or vehicle. Abdominal surgery (laparotomy-cecum palpation) was performed 1-2 h before the dark phase. The food intake and meal structures were monitored using an automated monitoring system for mice. Brain sections were processed for c-Fos immunoreactivity (ir) 2-h after abdominal surgery. Abdominal surgery significantly reduced bouts, meal frequency, size and duration, and time spent on meals, and increased inter-meal interval and satiety ratio resulting in 92-86% suppression of food intake at 2-24 h post-surgery compared with control group (no surgery). RKT significantly increased bouts, meal duration and the cumulative 12-h food intake by 11%. Abdominal surgery increased c-Fos in the prelimbic, cingulate and insular cortexes, and autonomic nuclei, such as the bed nucleus of the stria terminalis, central amygdala, hypothalamic supraoptic (SON), paraventricular and arcuate nuclei, Edinger-Westphal nucleus (E-W), lateral periaqueduct gray (PAG), lateral parabrachial nucleus, locus coeruleus, ventrolateral medulla and nucleus tractus solitarius (NTS). RKT induced a small increase in c-Fos-ir neurons in the SON and E-W of control mice, and in mice with surgery there was an increase in the lateral PAG and a decrease in the NTS. These findings indicate that abdominal surgery inhibits food intake by increasing both satiation (meal duration) and satiety (meal interval) and activates brain circuits involved in pain, feeding behavior and stress that may underlie the alterations of meal pattern and food intake inhibition. RKT improves food consumption post-surgically that may involve modulation of pain pathway.

Alcohol and nicotine are the two most co-abused drugs in the world. Previous studies have shown that nicotine can increase alcohol drinking in nondependent rats, yet it is unknown whether nicotine facilitates the transition to alcohol dependence. We tested the hypothesis that chronic nicotine will speed up the escalation of alcohol drinking in rats and that this effect will be accompanied by activation of sparsely distributed neurons (neuronal ensembles) throughout the brain that are specifically recruited by the combination of nicotine and alcohol. Rats were trained to respond for alcohol and made dependent using chronic, intermittent exposure to alcohol vapor, while receiving daily nicotine (0.8 mg/kg) injections. Identification of neuronal ensembles was performed after the last operant session, using immunohistochemistry. Nicotine produced an early escalation of alcohol drinking associated with compulsive alcohol drinking in dependent, but not in nondependent rats (air exposed), as measured by increased progressive-ratio responding and increased responding despite adverse consequences. The combination of nicotine and alcohol produced the recruitment of discrete and phenotype-specific neuronal ensembles (∼4-13% of total neuronal population) in the nucleus accumbens core, dorsomedial prefrontal cortex, central nucleus of the amygdala, bed nucleus of stria terminalis, and posterior ventral tegmental area. Blockade of nicotinic receptors using mecamylamine (1 mg/kg) prevented both the behavioral and neuronal effects of nicotine in dependent rats. These results demonstrate that nicotine and activation of nicotinic receptors are critical factors in the development of alcohol dependence through the dysregulation of a set of interconnected neuronal ensembles throughout the brain.

During nest building in zebra finches (Taeniopygia guttata), several regions in the social behaviour network and the dopaminergic reward system, which are two neural circuits involved in social behaviour, appear to be active in male and female nest-building finches. Because the nonapeptides, mesotocin and vasotocin and the neurotransmitter, dopamine, play important roles in avian social behaviour, we tested the hypothesis that mesotocinergic-vasotocinergic and dopaminergic neuronal populations in the social behaviour network and dopaminergic reward system, respectively, are active during nest building. We combined immunohistochemistry for Fos (an indirect marker of neuronal activity) and vasotocin, mesotocin or tyrosine hydroxylase on brain tissue from nest-building and non-nest-building male and female zebra finches and compared Fos immunoreactivity in these neuronal populations with the variation in nest-building behaviour. Fos immunoreactivity in all three types of neuronal populations increased with some aspect of nest building: (i) higher immunoreactivity in a mesotocinergic neuronal population of nest-building finches compared to controls; (ii) increased immunoreactivity in the vasotocinergic neuronal populations in relation to the amount of material picked up by nest-building males and the length of time that a male spent in the nest with his mate; and (iii) increased immunoreactivity in a dopaminergic neuronal population in relation to the length of time that a male nest-building finch spent in the nest with his mate. Taken together, these findings provide evidence for a role of the mesotocinergic-vasotocinergic and dopaminergic systems in avian nest building.

Adult obese Zucker rats (OZR; greater than 12 wk) develop elevated sympathetic nerve activity (SNA) and mean arterial pressure (MAP) with impaired baroreflexes compared with adult lean Zucker rats (LZR) and juvenile OZR (6-7 wk). In adult OZR, baroreceptor afferent nerves respond normally to changes in MAP, whereas electrical stimulation of baroreceptor afferent fibers produces smaller reductions in SNA and MAP compared with LZR. We hypothesized that impaired baroreflexes in OZR are linked to reduced activation of brain stem sites that mediate baroreflexes. In conscious adult rats, a hydralazine (HDZ)-induced reduction in MAP evoked tachycardia that was initially blunted in OZR, but equivalent to LZR within 5 min. In agreement, HDZ-induced expression of c-Fos in the rostral ventrolateral medulla (RVLM) was comparable between groups. In contrast, phenylephrine (PE)-induced rise in MAP evoked markedly attenuated bradycardia with dramatically reduced c-Fos expression in the nucleus tractus solitarius (NTS) of adult OZR compared with LZR. However, in juvenile rats, PE-induced hypertension evoked comparable bradycardia in OZR and LZR with similar or augmented c-Fos expression in NTS of the OZR. In urethane-anesthetized rats, microinjections of glutamate into NTS evoked equivalent decreases in SNA, heart rate (HR), and MAP in juvenile OZR and LZR, but attenuated decreases in SNA and MAP in adult OZR. In contrast, microinjections of glutamate into the caudal ventrolateral medulla, a target of barosensitive NTS neurons, evoked comparable decreases in SNA, HR, and MAP in adult OZR and LZR. These data suggest that OZR develop impaired glutamatergic activation of the NTS, which likely contributes to attenuated baroreflexes in adult OZR.

Many behavioral, physiological, and anatomical studies utilize animal models to investigate human striatal pathologies. Although commonly used, rodent striatum may not present the optimal animal model for certain studies due to a lesser morphological complexity than that of non-human primates, which are increasingly restricted in research. As an alternative, the tree shrew could provide a beneficial animal model for studies of the striatum. The gross morphology of the tree shrew striatum resembles that of primates, with separation of the caudate and putamen by the internal capsule. The neurochemical anatomy of the ventral striatum, specifically the nucleus accumbens, has never been examined. This major region of the limbic system plays a role in normal physiological functioning and is also an area of interest for human striatal disorders. The current study uses immunohistochemistry of calbindin and tyrosine hydroxylase (TH) to determine the ultrastructural organization of the nucleus accumbens core and shell of the tree shrew (Tupaia glis belangeri). Stereology was used to quantify the ultrastructural localization of TH, which displays weaker immunoreactivity in the core and denser immunoreactivity in the shell. In both regions, synapses with TH-immunoreactive axon terminals were primarily symmetric and showed no preference for targeting dendrites versus dendritic spines. The results were compared to previous ultrastructural studies of TH and dopamine in rat and monkey nucleus accumbens. Tree shrews and monkeys show no preference for the postsynaptic target in the shell, in contrast to rats which show a preference for synapsing with dendrites. Tree shrews have a ratio of asymmetric to symmetric synapses formed by TH-immunoreactive terminals that is intermediate between rats and monkeys. The findings from this study support the tree shrew as an alternative model for studies of human striatal pathologies.

In sensory systems, peripheral organs convey sensory inputs to relay networks where information is shaped by local microcircuits before being transmitted to cortical areas. In the olfactory system, odorants evoke specific patterns of sensory neuron activity that are transmitted to output neurons in olfactory bulb (OB) glomeruli. How sensory information is transferred and shaped at this level remains still unclear. Here we employ mouse genetics, 2-photon microscopy, electrophysiology and optogenetics, to identify a novel population of glutamatergic neurons (VGLUT3+) in the glomerular layer of the adult mouse OB as well as several of their synaptic targets. Both peripheral and serotoninergic inputs control VGLUT3+ neurons firing. Furthermore, we show that VGLUT3+ neuron photostimulation in vivo strongly suppresses both spontaneous and odour-evoked firing of bulbar output neurons. In conclusion, we identify and characterize here a microcircuit controlling the transfer of sensory information at an early stage of the olfactory pathway.

Agonists at the mu opioid receptor (MOR) are widely recognized for their effects on reward and pain. Although prior studies have attributed some of these effects to MORs on GABA neurons in the ventral tegmental area (VTA), recent studies have identified a region of particularly strong MOR immunostaining residing caudal to the VTA, in a region denoted the rostromedial tegmental nucleus (RMTg).

Locus coeruleus (LC) consists of a densely packed nuclear core and a surrounding plexus of dendritic zone, which is further divided into several subregions. Whereas many limbic-related structures topographically target specific subregions of the LC, the precise projections from two limbic areas, that is, medial prefrontal cortex (mPFC) and dorsal raphe (DR), have not been investigated. The goal of the present study is to identify and compare the distribution patterns of mPFC and DR afferent terminals to the LC nuclear core as opposed to specific pericoerulear dendritic regions (Peri-LC). To address these issues, anterograde tracer injections were combined with dopamine-β-hydroxylase (DBH) immunofluorescent staining to reveal the distribution patterns around the LC nuclear complex. Our data suggest that both mPFC-LC and DR-LC projections exhibit selective afferent terminal patterns. More specifically, mPFC-LC projecting fibers mainly target the rostromedial Peri-LC, whereas DR-LC projecting fibers demonstrate a preference to the caudal juxtaependymal Peri-LC. Thus, our present findings provide further evidences that afferents to the LC are topographically organized. Understanding the relationship among different inputs to the LC may help to elucidate the organizing principle which likely governs the interactions between the broad afferent sources of the LC and its global efferent targets.

In the present study, we applied the principles of immunoblotting and light microscopy immunohistochemistry to develop a combined methodology that allows obtaining optical density data in films, as well as morphological and protein distribution data on slides using the same brain tissue section, thus maximizing the data obtained from a single sample. This is especially important when experiments are performed using very valuable or unique tissue samples, which is a very common case in the study of the human brain. The ideal methodology should combine the possibility of measuring levels of expression of a marker, and the capability to map accurately the distribution of that marker in the region of interest. To achieve this, two things are required: first, the technique needs to be sensitive enough to obtain optical density or intensity measurements of the marker, and second, a good preservation of the tissue is needed for the study of distribution patterns and morphological analysis. Here we show that our combined methodology produced reliable results for different tissue preservation conditions (fresh-frozen and fixed tissue), in different species (rat and human), in different brain areas (substantia nigra and striatum), and for the detection of different markers (tyrosine hydroxylase and μ-opioid receptor). This methodology also combines the accuracy of optical density data acquisition in film with obtaining histological slides from the same sample. In summary, the methodology proposed here is very versatile and does not require the use of specialized equipment, other than the routine equipment present in an anatomy laboratory.

The sympathoadrenal system is the main source of catecholamines (CAs) in adipose tissues and therefore plays the key role in the regulation of adipose tissue metabolism. We recently reported existence of an alternative CA-producing system directly in adipose tissue cells, and here we investigated effect of various stressors-physical (cold) and emotional stress (immobilization) on dynamics of this system. Acute or chronic cold exposure increased intracellular norepinephrine (NE) and epinephrine (EPI) concentration in isolated rat mesenteric adipocytes. Gene expression of CA biosynthetic enzymes did not change in adipocytes but was increased in stromal vascular fraction (SVF) after 28 day cold. Exposure of rats to a single IMO stress caused increases in NE and EPI levels, and also gene expression of CA biosynthetic enzymes in adipocytes. In SVF changes were similar but more pronounced. Animals adapted to a long-term cold exposure (28 days, 4°C) did not show those responses found after a single IMO stress either in adipocytes or SVF. Our data indicate that gene machinery accommodated in adipocytes, which is able to synthesize NE and EPI de novo, is significantly activated by stress. Cold-adapted animals keep their adaptation even after an exposure to a novel stressor. These findings suggest the functionality of CAs produced endogenously in adipocytes. Taken together, the newly discovered CA synthesizing system in adipocytes is activated in stress situations and might significantly contribute to regulation of lipolysis and other metabolic or thermogenetic processes.