Immunoreactive Neurons Research Articles

Doublecortin-Expressing Neurons in Chinese Tree Shrew Forebrain Exhibit Mixed Rodent and Primate-Like Topographic Characteristics.

Doublecortin (DCX) is transiently expressed in new-born neurons in the subventricular zone (SVZ) and subgranular zone (SGZ) related to adult neurogenesis in the olfactory bulb (OB) and hippocampal formation. DCX immunoreactive (DCX+) immature neurons also occur in the cerebral cortex primarily over layer II and the amygdala around the paralaminar nucleus (PLN) in various mammals, with interspecies differences pointing to phylogenic variation. The tree shrews (Tupaia belangeri) are phylogenetically closer to primates than to rodents. Little is known about DCX+ neurons in the brain of this species. In the present study, we characterized DCX immunoreactivity (IR) in the forebrain of Chinese tree shrews aged from 2 months- to 6 years-old (n = 18). DCX+ cells were present in the OB, SVZ, SGZ, the piriform cortex over layer II, and the amygdala around the PLN. The numerical densities of DCX+ neurons were reduced in all above neuroanatomical regions with age, particularly dramatic in the DG in the 5–6 years-old animals. Thus, DCX+ neurons are present in the two established neurogenic sites (SVZ and SGZ) in the Chinese tree shrew as seen in other mammals. DCX+ cortical neurons in this animal exhibit a topographic pattern comparable to that in mice and rats, while these immature neurons are also present in the amygdala, concentrating around the PLN as seen in primates and some nonprimate mammals.

Behavioral profile in a Dctn1G71A knock-in mouse model of Perry disease

Perry disease (Perry syndrome) is a rare, rapidly progressive, autosomal dominant neurodegenerative disease characterized by parkinsonism, depression/apathy, weight loss, and respiratory symptoms including central hypoventilation. It is caused by missense mutations (e.g. p.G71A) in the DCTN1 gene. We previously generated transgenic mice that expressed human DCTN1G71A mutant protein under the control of Thy1 promoter. These mice exhibited apathy-like behavior and parkinsonism. However, it is possible that this phenotype was due to a gene-dosage imbalance or transgene insertion position. To circumvent these potential caveats, we have generated a knock-in mouse model carrying a p.G71A mutation in Dctn1. Heterozygous Dctn1G71A and wild-type littermates were subjected to a battery of behavioral analyses. Furthermore, immunohistochemistry for tyrosine hydroxylase (TH) was performed on brain sections of these mice, and TH signal intensity in substantia nigral neurons was quantified. Dctn1G71A mice were immobile for longer than wild-type mice of the same age and sex in the tail-suspension test, revealing depressive characteristics. In addition, the beam-walking test and pole test detected motor deficits in Dctn1G71A female mice. Finally, immunostaining revealed a decrease in TH immunoreactivity in neurons of the substantia nigra in the Dctn1G71A mice. Collectively, heterozygous Dctn1G71A mice showed depression-like behavior, motor deficits, and a functional reduction in substantia nigral neurons, as judged by TH immunostaining, thereby exhibiting multiple features of Perry disease. Hence, this mouse model will be useful in elucidating pathological mechanisms of Perry disease and for developing novel therapeutic strategies against it.

Regulation of Parvalbumin Interactome in the Perilesional Cortex after Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) causes 10–20% of structural epilepsy, with seizures typically originating in the cortex. Alterations in the neuronal microcircuits in the cortical epileptogenic zone, however, are poorly understood. Here, we assessed TBI-induced changes in perisomatic gamma aminobutyric acid (GABA)-ergic innervation in the perilesional cortex. We hypothesized that TBI will damage parvalbumin (PV)-immunoreactive inhibitory neurons and induce regulation of the associated GABAergic molecular interactome. TBI was induced in adult male Sprague-Dawley rats by lateral fluid-percussion injury. At 1-month post-TBI, the number of PV-positive somata was plotted on unfolded cortical maps and the distribution and density of immunopositive terminals analyzed. Qualitative analysis revealed either patchy microlesions of several hundred micrometers in diameter or diffuse neuronal loss. Quantitative analysis demonstrated a reduction in the number of PV-positive interneurons in patches down to 0% of that in sham-operated controls in the perilesional cortex. In the majority of patches, the cell numbers ranged from 71% to 90% that of the controls. The loss of PV-positive somata was accompanied by decreased axonal labeling. In situ hybridization revealed downregulated PV mRNA expression in the perilesional cortex. Gene Set Enrichment Analysis indicated a robustly downregulated expression profile of PV-related genes, which was confirmed by quantitative reverse transcriptase polymerase chain reaction. Specifically, we found that genes encoding postsynaptic GABA-A receptor genes, Gabrg2 and Gabrd, were downregulated in TBI animals compared with controls. Our data suggests that patchy reduction in PV-positive perisomatic inhibitory innervation contributes to the development of focal cortical inhibitory deficit after TBI.

Patterns of Nerve Fibre Impairments and Neuronal Activation in Male Diabetic Rats With and Without Mechanical Allodynia: A Comparative Study

BackgroundIt is still clinically difficult to definitively distinguish between painful and nonpainful diabetic peripheral neuropathy (DPN). In this study, pain patterns were further categorized; diabetic rats were grouped according to the presence or absence of mechanical allodynia (MA), which is a hallmark of neuropathic pain, and comparisons were made between diabetic rats with and without MA. MethodsDiabetes was established in rats by a single intraperitoneal streptozotocin injection, and vehicle injection was administered in the control group. Pain behaviour tests for MA and thermal hyperalgesia were performed every week. At week 4, the diabetic group with thermal hyperalgesia was further grouped by the presence of MA. Morphometric analysis of sciatic nerves and myelin basic protein quantification were conducted. The numbers of c-Fos–immunoreactive neurons in both the dorsal root ganglion (DRG) and the spinal dorsal horn (SDH) were determined. ResultsDiabetic rats with MA had more severe impairment of myelinated nerve fibres than those without MA (p<0.001). Higher percentages of NF-200–positive neurons in the DRG were c-Fos immunoreactive in the DPN-with-MA group than in the DNP-without-MA group (p=0.014). The numbers of c-Fos–immunoreactive neurons in both the superficial (I–II) and deeper (III–V) laminae of the SDH in the DPN-with-MA group were larger than those in the subgroups without MA (p<0.001). ConclusionsThe impairment of primary myelinated fibres and the pattern of neuronal activation in both the DRG and the SDH are specific features that differentiate diabetic rats with MA from those without MA.

Variable expression of mitochondrial complex IV in the course of nigral intracellular accumulation of α-synuclein

IntroductionParkinson's disease (PD) is a neurodegenerative disease characterized by the deposition of disease-associated α-synuclein, which is thought to follow a sequential distribution in the human brain. Accordingly, α-Synuclein pathology affects the substantia nigra (SN) only in Braak stage 3 out of 6. Moreover, intracellular accumulation of α-synuclein follows maturation from non-ubiquitinated (p62 negative) to ubiquitinated (p62 positive) forms (Lewy bodies). Mitochondrial dysfunction is thought to be a central player in the pathogenesis of PD. It is not clear whether the nigral neurons already show mitochondrial alterations in stages preceding the deposition of α-synuclein in the SN, and how deposition of pre-aggregates or ubiquitinated mature inclusions relate to this. MethodsUsing cell-based morphometric immunohistochemistry we evaluated the volume density of mitochondrial complex-IV (COX-IV) immunoreactivity in SN neurons lacking or showing α-synuclein deposits in non-diseased individuals and those with Lewy body pathology Braak stage <3 lacking nigral α-synuclein pathology and Braak stage >3 with prominent nigral α-synuclein deposition. ResultsIncreased volume density of COX-IV immunoreactivity appears before detectable pathological α-synuclein in nigral neurons. The volume density decreases significantly as pathological pre-aggregates of α-synuclein accumulates in the neurons and remains at a low level in neurons with p62 positive Lewy bodies. ConclusionsCOX-IV expression shows a change before and during accumulation of α-synuclein in the SN underpinning the role of early mitochondrio protective therapy strategies in PD.

The expression of diacylglycerol kinase isoforms α and ζ correlates with the progression of experimental autoimmune encephalomyelitis in rats

Multiple sclerosis (MS) is characterized by neuroinflammation and neurodegeneration, whose precise processes are not fully understood. Diacylglycerol kinase (DGK) isozymes of α, β, γ and ζ expressed abundantly in the brain and/or the immune system, may be regulatory targets for MS. In this study, we analyzed the four DGK isozymes along the induction, peak and recovery phases in an experimental autoimmune encephalomyelitis (EAE) rat model of MS. The expression of these DGK isozymes and the diacylglycerol (DAG) pathway in the EAE rat brainstems were analyzed by qRT-PCR, immunohistochemistry, immunofluorescence double staining, western blotting and ELISA. Our results showed that the mRNA content of the four DGK isozymes decreased significantly, and their immunoreactivity in myelin sheathes (DGKα, β) and neurons (DGKγ, ζ) became weaker at the beginning of the induction phase. With the progressive increase in clinical signs, DGKα, DGKγ and DGKζ mRNA increased and DGKβ mRNA decreased, and microglia were involved in the formation of perivascular cuffing. In the peak phase, both DGKα and DGKζ were expressed in neurons and inflammatory cells, and DGKζ was also positive in microglia. During the recovery phase, the mRNA content and immunoreactivity of these DGK isozymes generally reached normal levels. Moreover, our results revealed that changes in DAG accumulation and PKCδ phosphorylation were almost the same as those of DGKα and DGKζ mRNA. In summary, the four DGK isozymes are involved in the EAE process. The predominant and broad presence of DGKα and DGKζ suggests that they may regulate the pathological process by attenuating DAG/PKCδ pathway signaling during EAE evolution.

The Reassessed Impact of Nicotine against Neurotoxicity in Mesencephalic Dopaminergic Cell Cultures and Neuroblastoma N18TG2 Cells.

Neuroprotective effects of nicotine are still under debate, so further studies on its effectiveness against Parkinson's disease are required. In our present study, we used primary dopaminergic cell cultures and N18TG2 neuroblastoma cells to investigate the effect of nicotine and its neuroprotective potential against rotenone toxicity. Nicotine protected dopaminergic (tyrosine hydroxylase immunoreactive) neurons against rotenone. This effect was not nAChR receptor-dependent. Moreover, the alkaloid at a concentration of 5 µM caused an increase in neurite length, and at a concentration of 500 µM, it caused an increase in neurite count in dopaminergic cells exposed to rotenone. Nicotine alone was not toxic in either cell culture model, while the highest tested concentration of nicotine (500 µM) caused growth inhibition of N18TG2 neuroblastoma cells. Nicotine alone increased the level of glutathione in both cell cultures and also in rotenone-treated neuroblastoma cells. The obtained results may be helpful to explain the potential neuroprotective action of nicotine on neural cell cultures.

Activation of CRF1 receptors expressed in brainstem autonomic nuclei stimulates colonic enteric neurons and secreto-motor function in male rats.

Hypothalamic corticotropin-releasing factor (CRF) receptor 1 (CRF1 ) plays a role in acute stress-related stimulation of colonic motor function. Less is known on CRF1 signaling in the brainstem. We investigate CRF1 expression in the brainstem and the colonic response to 4th ventricle (4V) injection of CRF and urocortin (Ucn) 2 (3 µg/rat) in chronically cannulated male rats. Transcripts of CRF1 wild-type 1a and splice variants 1c, 1e, 1f, 1o along with three novel variants 1a-2 (desK-110 in exon 5), 1p (-exon 7), and 1q (exon 5 extension) were identified in the pons and medulla. The area postrema, nucleus tractus solitarius, dorsal motor nucleus of the vagus, locus coeruleus, and Barrington's nucleus isolated by laser capture microdissection expressed 1a, 1a-2, and 1p but not 1q. Compared to 4V vehicle, 4V CRF induced fecal pellet output (FPO) and diarrhea that were blocked by the CRF antagonist, astressin-B. CRF2 agonist, Ucn2 had no effect on basal or CRF-induced FPO. CRF actions were correlated with the induction of c-Fos immunoreactivity in myenteric neurons of the proximal and distal colon (pC, dC) and submucosal neurons of dC. c-Fos immunoreactivity occurred in 39% and 37% of myenteric cholinergic and 7% and 58% of nitrergic neurons in the pC and dC, respectively. CRF1a and its splice variants are expressed in brainstem nuclei, and activation of CRF1 signaling at the level of the brainstem stimulates colonic secretory-motor function through activation of colonic enteric neurons.

Morphology of the digestive system in carnivorous freshwater dourado Salminus brasiliensis.

The digestive system of teleost shows remarkable functional and morphological diversity. In this study, the digestive tract and accessory organs of dourado Salminus brasiliensis are characterized using anatomical, histological, histochemical and immunohistochemical analyses. The existence of taste buds bordered by microridges in the oesophagus of dourado was recorded for the first time, thus showing that the species drives food intake by either swallowing or rejecting the food item. The Y-shaped stomach of dourado consisted of cardiac, cecal and pyloric regions with tubular gastric glands registered solely in the cardiac and cecal segments. The intestine is a short N-shaped tube with two loops, an intestinal coefficient of 0.73. The structure of pyloric caeca is similar to that of the intestine wall, comprising tunica mucosa, tela submucosa, tunica muscularis and tunica serosa layers. Histochemical analyses revealed an increased incidence of goblet cells from the midgut to the hindgut segment. A well-developed enteric plexus of scattered nerve cell and fibres are found along the digestive tract, and the calcitonin gene-related peptide (CGRP) immunoreactive neurons and fibres were identified in the myenteric plexus from the oesophagus to the hindgut. The exocrine pancreas appears diffuse in the mesentery around the stomach, intestine and also reaches the liver, and the endocrine pancreas is organized as a few islets of Langerhans. The liver comprises three distinct, asymmetric lobes, and the portal triad arrangement was registered in this tissue.

Subcellular localization of neuronal nuclei (NeuN) antigen in size and calcitonin gene-related peptide (CGRP) populations of dorsal root ganglion (DRG) neurons during acute peripheral inflammation

Pseudo-unipolar cell bodies of somatosensory primary neurons are located in the dorsal root ganglia (DRG). The somatic and peripheral domains of DRG neurons are often studied in sensory pain research to understand molecular mechanisms involved in the activation of pain and maintenance of inflammation. Adjuvant-induced arthritis (AIA) is an inflammatory model that elicits a robust and rapid onset immune response with a maximal swelling period of 24−48 h and persisting for several weeks. The AIA model in the hind paw of the rat elicits a potent inflammatory response of the dermis and epidermis, leading to protein expression changes for sensitization of many DRG neurons; however, it is unknown if the AIA model in the hind paw of the rat induces DRG neuronal injury, necrosis, or apoptosis at the somatic level. Neuronal nuclei (NeuN) antigen is a biomarker for post-mitotic neurons, neuronal identification, protein alterations, injury, and loss. Calcitonin gene-related peptide (CGRP) is expressed in C and Aδ DRG neurons, a subset of DRG neurons known to play a role in peripheral sensitization. The focus of this research was to evaluate the expression pattern of NeuN immunoreactivity, in size (soma) and CGRP subpopulations of DRG neurons in naïve and inflamed groups. Confirmed by both immunofluorescence and immunoprecipitation, DRG neuronal expression of NeuN was localized to nuclear and cytoplasmic subcellular compartments. NeuN increased within the nucleus of small CGRP positive DRG neurons during inflammation, indicating a potential role for NeuN in a subset of nociceptive neurons.

FMRF-NH2 -related neuropeptides in Biomphalaria spp., intermediate hosts for schistosomiasis: Precursor organization and immunohistochemical localization.

Freshwater snails of the genus Biomphalaria serve as intermediate hosts for the digenetic trematode Schistosoma mansoni, the etiological agent for the most widespread form of intestinal schistosomiasis. As neuropeptide signaling in host snails can be altered by trematode infection, a neural transcriptomics approach was undertaken to identify peptide precursors in Biomphalaria glabrata, the major intermediate host for S. mansoni in the Western Hemisphere. Three transcripts that encode peptides belonging to the FMRF-NH2 -related peptide (FaRP) family were identified in B. glabrata. One transcript encoded a precursor polypeptide (Bgl-FaRP1; 292 amino acids) that included eight copies of the tetrapeptide FMRF-NH2 and single copies of FIRF-NH2 , FLRF-NH2 , and pQFYRI-NH2 . The second transcript encoded a precursor (Bgl-FaRP2; 347 amino acids) that comprised 14 copies of the heptapeptide GDPFLRF-NH2 and 1 copy of SKPYMRF-NH2 . The precursor encoded by the third transcript (Bgl-FaRP3; 287 amino acids) recapitulated Bgl-FaRP2 but lacked the full SKPYMRF-NH2 peptide. The three precursors shared a common signal peptide, suggesting a genomic organization described previously in gastropods. Immunohistochemical studies were performed on the nervous systems of B. glabrata and B. alexandrina, a major intermediate host for S. mansoni in Egypt. FMRF-NH2 -like immunoreactive (FMRF-NH2 -li) neurons were located in regions of the central nervous system associated with reproduction, feeding, and cardiorespiration. Antisera raised against non-FMRF-NH2 peptides present in the tetrapeptide and heptapeptide precursors labeled independent subsets of the FMRF-NH2 -li neurons. This study supports the participation of FMRF-NH2 -related neuropeptides in the regulation of vital physiological and behavioral systems that are altered by parasitism in Biomphalaria.

Regulation of TWIK-related K+ channel 1 in the anterior hippocampus of patients with temporal lobe epilepsy with comorbid depression

Epilepsy with comorbid depression has recently attracted increasing attention. Temporal lobe epilepsy (TLE) may represent an increased risk of developing depression, especially if the seizures do not generalize. The two-pore domain potassium channel-TWIK-related K+ channel (TREK-1) plays important roles in both epilepsy and depression. However, the changes in its expression in patients with epilepsy with comorbid depression remain unclear. In the present study, we analyzed depressive symptoms using neuropsychiatric scales in forty-two patients with drug-resistant TLE, who also underwent EEG in waking and sleeping states, as well as 3.0 T brain MRI. We tested for TREK-1 positive neurons and microglial cells in the anterior hippocampi of patients with drug-resistant TLE with and without comorbid depression (n=5/group). Approximately 31% of patients with TLE had comorbid depression (13/42). Meanwhile, the patients who had hippocampal sclerosis had much higher scores on the depression rating scale. The results indicated the contribution of hippocampal sclerosis to the development of depression. Immunostaining of TREK-1 channels was observed in neurons and glia in the anterior hippocampus. Increased immunoreactivity of TREK-1 neurons was observed in the hippocampi of patients with TLE with comorbid depression compared with nondepressed patients with TLE. TREK-1 was expressed in almost all microglia. Curiously, more activated TREK-1-positive microglia were observed in patients with TLE with depression than in those without depression. The results suggested that a change in TREK-1 immunoreactivity was involved, at least partly, in the development of depression as a comorbidity of TLE. Imbalance of the TREK-1 channel may be a potential target for the treatment of patients with epilepsy with comorbid depression.

Melatonin mediates monochromatic light-induced expression of somatostatin in the hypothalamus and pituitary of chicks

Melatonin (MEL) plays an important role in regulating growth and development of organisms and the cellular metabolism. This study was conducted to explore the role of MEL in mediating monochromatic light-induced secretion of somatostatin (SST) in the hypothalamus and pituitary in chicks. Pinealectomy models of newly hatched broilers were exposed to white (WL), red (RL), green (GL), and blue (BL) lights. The results showed that SST immunoreactive neurons and fibers were distributed in the hypothalamus. SST and SST receptor 2 (SSTR2) mRNA and protein levels in the hypothalamus and pituitary were higher in chicks exposed to RL than in chicks exposed to GL and BL. However, after pinealectomy, the mRNA and protein levels of SST and SSTR2 in the hypothalamus and pituitary in the different light groups were increased, and the differences between the groups disapeared. The expression trend of SSTR5 mRNA in the pituitary was the idential to that of SSTR2 mRNA in the pituitary. In vitro, exogenous SST inhibited growth hormone (GH) secretion, and selective antogonists of SSTR2 and SSTR5 promoted GH secretion. Selective antogonists of the melatonin receptor 1b (Mel1b) and Mel1c increased the relative concentrations of SST in the adenohypophysis cells. These results indicated that monochromatic light affects the expression of SST in chick hypothalamus and pituitary. MEL, via Mel1b and Mel1c, decreased SST secretion under GL, which was associated with the inhibition of SST, SSTR2, and SSTR5 in adenohypophysis cells.

Diabetes Affects the Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP)-Like Immunoreactive Enteric Neurons in the Porcine Digestive Tract.

Diabetic gastroenteropathy is a common complication, which develops in patients with long-term diabetes. The pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide known for its cytoprotective properties and plays an important role in neuronal development, neuromodulation and neuroprotection. The present study was designed to elucidate, for the first time, the impact of prolonged hyperglycaemia conditions on a population of PACAP-like immunoreactive neurons in selected parts of the porcine gastrointestinal tract. The experiment was conducted on 10 juvenile female pigs assigned to two experimental groups: The DM group (pigs with streptozocin-induced diabetes) and the C group (control pigs). Diabetes conditions were induced by a single intravenous injection of streptozocin. Six weeks after the induction of diabetes, all animals were euthanised and further collected, and fixed fragments of the stomach, duodenum, jejunum, ileum and descending colon were processed using the routine double-labelling immunofluorescence technique. Streptozotocin-induced hyperglycaemia caused a significant increase in the population of PACAP-containing enteric neurons in the porcine stomach, small intestines and descending colon. The recorded changes may result from the direct toxic effect of hyperglycaemia on the ENS neurons, oxidative stress or inflammatory conditions accompanying hyperglycaemia and suggest that PACAP is involved in regulatory processes of the GIT function in the course of diabetes.

Magnetic resonance imaging under isoflurane anesthesia alters cortical cyclooxygenase-2 expression and glial cell morphology during sepsis-associated neurological dysfunction in rats.

BackgroundMagnetic resonance imaging (MRI) of rodents combined with histology allows to determine what mechanisms underlie functional and structural brain changes during sepsis‐associated encephalopathy. However, the effects of MRI performed in isoflurane‐anesthetized rodents on modifications of the blood‐brain barrier and the production of vasoactive prostaglandins and glia cells, which have been proposed to mediate sepsis‐associated brain dysfunction, are unknown.MethodsThis study addressed the effect of MRI under isoflurane anesthesia on blood‐brain barrier integrity, cyclooxygenase‐2 expression, and glial cell activation during cecal ligature and puncture‐induced sepsis‐associated brain dysfunction in rats.ResultsCecal ligature and puncture reduced food intake and the righting reflex. MRI under isoflurane anesthesia reduced blood‐brain barrier breakdown, decreased circularity of white matter astrocytes, and increased neuronal cyclooxygenase‐2 immunoreactivity in the cortex 24 hours after laparotomy. In addition, it annihilated cecal ligature and puncture‐induced increased circularity of white matter microglia. MRI under isoflurane anesthesia, however, did not alter sepsis‐associated perivascular cyclooxygenase‐2 induction.ConclusionThese findings indicate that MRI under isoflurane anesthesia of rodents can modify neurovascular and glial responses and should, therefore, be interpreted with caution.

Granulocyte-colony stimulating factor, a potential candidate for the treatment of Parkinson's disease.

Granulocyte colony-stimulating factor (G-CSF) activates the PI3K/Akt pathway to exert neuroprotective effects. The current study aimed to determine if G-CSF reverses behavioral deficits, even after motor malfunction occurs in Paraquat (PQ)-treated mice. Male C57BL/6 mice (8 weeks old) were divided into 3 groups: PQ + G-CSF-treated group (N.=8); PQ + saline-treated group (N.=8); and saline-treated control group (N.=8). Spontaneous locomotor activity was evaluated together with the pole test. The DA, 3, 4-dihydroxyphenyl acetic acid (DOPAC), and homovanillic acid (HVA) levels in the bilateral striatum were determined by HPLC. The number of substantia nigra pars compacta tyrosine hydroxylase (TH)-immunoreactive neurons was calculated using an unbiased cell counting stereology method, the activities of total GSH-PX and SOD, and the malondialdehyde (MDA) content were assessed. After G-CSF treatment, spontaneous motor activity and the T<inf>turn</inf> and T<inf>LA</inf> times in the CSF group were significantly lower than the control group, and the striatal dopamine level in the striatum and the number of TH-positive neurons in the substantia nigra (SN) were significantly increased compared to the control group (5478±654 vs. 3647±488 DA neurons, P<0.05). Compared to the control group, the GSH-PX and SOD activities were increased, while the MDA level was significantly decreased in the SN (P<0.05). The data strongly suggest that G-CSF reverses behavioral deficits in PQ-treated mice with movement disorders. Thus, G-CSF may be utilized as a prospective drug candidate for the treatment of Parkinson's disease.

Cocaine and amphetamine regulated transcript peptide (CART) in the tadpole brain: Response to different energy states

Cocaine- and amphetamine-regulated transcript peptide (CART) is an anorexigenic neuropeptide known to play a key role in energy homeostasis across the vertebrate phyla. In the current study, we have investigated the response of the CART immunoreactive system to varying energy states in the brain of a tadpole model. The pro-metamorphic tadpoles of Euphlyctis cyanophlyctis were fasted, or intracranially injected with glucose or 2-deoxy-d-glucose (2DG; an antagonist to glucose inducing glucoprivation) and the response of the CART containing system in various neuroanatomical areas was studied using immunohistochemistry. Glucose administration increased the CART immunoreactivity in the entopeduncular neurons (EN), preoptic area (POA), ventral hypothalamus (vHy) and the Edinger Westphal nucleus (EW) while CART positive cells decrease in response to fasting and glucoprivation. A substantial decrease in CART was noted in the EW nucleus of tadpoles injected with 2DG. These regions might contain the glucose-sensing neurons and regulate food intake in anurans. Therefore, we speculate that the function of central CART and its antagonistic action with NPY in food and feeding circuitry of anurans is evolutionary conserved and might be responsible for glucose homeostasis.

Substance P-Immunoreactive Fiber Varicosities Appear to Innervate Galaninergic Perikarya in the Human Hypothalamus.

Introduction: Substance P (SP) is a member of the tachykinin family. In the central nervous system, SP participates among others, in the regulation of pain, learning, memory, emotion, and sexual functions. In the periphery, SP affects the gastrointestinal, cardiovascular, and urinary systems. Galanin, similarly to SP, appears to be involved in wide range of physiologic functions, including cognition, waking and sleep, feeding, mood, blood pressure, reproduction, and development, where acts as a trophic factor. The similar distribution of SP-immunoreactive (SP-IR) fibers and galanin-IR perikarya in the human hypothalamus suggests functional interaction between these neuropeptides. Methods: We have utilized double-label immunohistochemistry to reveal these putative juxtapositions. Results: The majority of galanin-IR neurons receive contacting SP-IR fibers that often cover a significant area of the galaninergic perikarya forming multiple en passant type contacts. These SP-galanin juxtapositions are located mainly in the basal part of the infundibulum/median eminence, populating the basal periventricular region as well as the basal perifornical area. Discussion: The density and the morphology of these associations suggest that these contacts are functional synapses and therefore may represent the morphological substrate of the control of SP on multiple functions regulated/modulated by galanin. SP via galanin may modulate anterior pituitary hormone secretion, as contrary to SP, high density of galanin immunoreactivity is present in the median eminence, and by innervating galanin-IR neurons projecting to other parts of the brain, SP can modulate indirectly their activities. Impact statement The present study is the first describing juxtapositions between the substance P (SP)-immunoreactive (IR) and galanin-IR neurons in the human hypothalamus. These juxtapositions may be functional synapses and they may represent the morphological substrate of the control of SP on the galaninergic system. SP via galanin may modulate anterior pituitary hormone secretion, as contrary to SP, high density of galanin immunoreactivity is present in the median eminence. Galanin, released into the hypothalamo-hypophyseal circulation, can reach the anterior pituitary and function as a hypophysiotropic substance and regulates anterior pituitary hormone secretion. SP by innervating galanin-IR neurons, which project to other parts of the brain, can modulate indirectly their activities.

Social interaction masking contributes to changes in the activity of the suprachiasmatic nucleus and impacts on circadian rhythms

Light is the most powerful temporal cue that entrains physiology and behavior through modulation of the suprachiasmatic nucleus (SCN) of the hypothalamus. However, on a daily basis, individuals face a combination of light and several non-photic cues, such as social interaction. In order to investigate whether SCN activity and SCN-driven rhythms are altered by social interaction, adult male C57BLJ/6 mice were maintained in groups of 3–4 animals per cage or 1 animal per cage (socially isolated) under 12:12 h / light:dark (LD) cycles or constant darkness (DD). Analysis of the two anatomical subdivisions (ventral, v and dorsal, d) of the medial SCN revealed an effect of housing conditions on the d-SCN but not on the v-SCN on the number of c-Fos immunoreactive (ir) neurons. As such, 2 h after the light-phase onset d-SCN c-Fos-ir number was lower in single-housed mice under LD. Importantly, under DD there were no effect of housing conditions in the number of c-Fos-ir SCN neurons. Social isolation increased the amplitude and strength of SCN-driven rhythm of body temperature (Tc) entrained to LD and it advanced its onset, uncoupling with spontaneous locomotor activity (SLA) rhythm, without altering endogenous Tc and SLA rhythms expressed under DD. Associated with reduced Tc in the light phase, single-housed mice showed reduced body weight. However, these phenotypes were not accompanied by changes in the number of c-Fos-ir neurons in the preoptic area (POA), which are known to regulate energy metabolism and Tc. Altogether, these results imply that the social interaction masking effect on the d-SCN is added to that of light stimulus, in order to achieve full c-Fos expression in the SCN, which, in turn seems to be required to maintain daily-phase coherence between the photo-entrained rhythms of Tc and SLA. There might be an inter-relationship between masking (social interaction) and entrainment stimulus (light) that impacts the circadian parameters of the photo-entrained Tc rhythm. As such, in the absence of social interactions a more robust Tc rhythm is shown. This inter-relationship seems to occur in the dorsal subdivision of the SCN but not in the POA.

Daily and Estral Regulation of RFRP-3 Neurons in the Female Mice.

Female reproductive success relies on proper integration of circadian- and ovarian- signals to the hypothalamic-pituitary-gonadal axis in order to synchronize the preovulatory LH surge at the end of the ovarian follicular stage with the onset of the main active period. In this study, we used a combination of neuroanatomical and electrophysiological approaches to assess whether the hypothalamic neurons expressing Arg-Phe amide-related peptide (RFRP-3), a gonadotropin inhibitory peptide, exhibit daily and estrous stage dependent variations in female mice. Furthermore, we investigated whether arginine vasopressin (AVP), a circadian peptide produced by the suprachiamatic nucleus regulates RFRP-3 neurons. The number of c-Fos–positive RFRP-3 immunoreactive neurons is significantly reduced at the day-to-night transition with no difference between diestrus and proestrus. Contrastingly, RFRP neuron firing rate is higher in proestrus as compared to diestrus, independently of the time of the day. AVP immunoreactive fibers contact RFRP neurons with the highest density observed during the late afternoon of diestrus and proestrus. Application of AVP increases RFRP neurons firing in the afternoon (ZT6-10) of diestrus, but not at the same time point of proestrus, indicating that AVP signaling on RFRP neurons may depend on circulating ovarian steroids. Together, these studies show that RFRP neurons integrate both daily and estrogenic signals, which downstream may help to properly time the preovulatory LH surge.