Relationship between stress and circulating levels of S100B protein

It has been proposed that S100B can be a marker for several pathological conditions including brain traumas, blood-brain barrier disruption, and ischemia. Because the hypothalamo-pituitary-adrenal axis is activated in these conditions, we investigated the role of glucocorticoids in the effects of stress on serum S100B. Restraint stress increased S100B levels in control and in adrenalectomized but not in corticosterone-injected rats. Adrenalectomy did not alter basal S100B. These results indicate a glucocorticoid-independent relationship between stress and S100B.     

Effects of long-term exposure of lemon essential oil odor on behavioral, hormonal and neuronal parameters in male and female rats

Behavioral, hormonal and neuronal responses to prolonged exposure to the volatile components of essential oil (EO) extracted from citrus lemon were investigated in male and female rats. Animals were exposed to the lemon essence for 2 weeks while in their cage. Anxiety was then determined with the elevated plus-maze apparatus while nociception was evaluated with a phasic thermal pain stimulus (plantar test) and with a chemical pain stimulus (formalin test). At the end of the experimental sessions, brain areas were dissected to measure beta-endorphin (beta-EP) concentrations in the hypothalamus and periaqueductal gray matter (PAG). Blood samples were collected to determine corticosterone plasma levels. In both sexes, prolonged EO exposure decreased the time spent in the open arms of the plus-maze apparatus. EO-exposed males and females showed higher thermal nociceptive thresholds than controls when tested with the plantar test apparatus. EO exposure induced female-specific decreases in formalin-induced pain behaviors during the formalin test. beta-EP concentrations in the hypothalamus and PAG were affected by EO. Corticosterone was lower in EO-exposed animals of both sexes than in their controls. These results suggest that long-term exposure to lemon EO can induce significant, at times sex-specific, changes in neuronal circuits involved in anxiety and pain.     

Intracellular calcium increase in epileptiform activity: modulation by levetiracetam and lamotrigine

PURPOSE: Alterations in neuronal calcium (Ca2+) homeostasis are believed to play an essential role in the generation and propagation of epileptiform events. Levetiracetam (LEV) and lamotrigine (LTG), novel antiepileptic drugs (AEDs), were tested on epileptiform events and the corresponding elevations in intracellular Ca2+ concentration ([Ca2+]i) recorded from rat neocortical slices. METHODS: Electrophysiological recordings were performed from single pyramidal neurons from a slice preparation. Spontaneous epileptiform events consisting of long-lasting, repetitive paroxysmal depolarization shifts (PDSs) and interictal spike activity were induced by reducing the magnesium concentration from the solution and by adding bicuculline and 4-aminopyridine. Simultaneously, microfluorimetric measurements of [Ca2+]i were performed. Optical imaging with Ca2+ indicators revealed a close correlation between Ca2+ transients and epileptiform events. RESULTS: Both LEV and LTG were able to reduce both amplitude and duration of PDSs, as well as the concomitant elevation in [Ca2+]i, in a dose-dependent fashion. Whole-cell patch-clamp recordings from isolated neocortical neurons revealed that LEV significantly reduced N-, and partially P/Q-type high-voltage-activated (HVA) Ca2+ currents, whereas sodium currents were unaffected. Interestingly, the inhibitory effects of LEV were mimicked and occluded by LTG or by a combination of omega-conotoxin GVIA and omega-agatoxin IVA, selective blockers of N- and P/Q-type HVA channels, respectively, suggesting a common site of action for these AEDs. CONCLUSIONS: These results demonstrate that large, transient elevations in neuronal [Ca2+]i correlate to epileptiform discharges. The antagonistic effects of LEV and LTG on [Ca2+]i overload might represent the basis for their anticonvulsant efficacy and could preserve neuronal viability.     

Nicotinic acetylcholine receptor subtypes in the rat sympathetic ganglion: pharmacological characterization, subcellular distribution and effect of pre- and postganglionic nerve crush

Nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic transmission in autonomic ganglia, which innervate and control the activity of most visceral organs. By combining ultrastructural, immunocytochemical, and pharmacological analyses, we characterized the nAChR subtypes in the rat superior cervical ganglion (SCG) and the effect of pre- and postganglionic nerve crush on their number in the ganglion and their distribution at the intraganglionic synapses. Binding with radioactive nicotinic ligands, immunoprecipitation, and immunolocalization experiments revealed the presence of different nAChR subtypes: those containing the alpha3 subunit associated with beta4 and/or beta2 subunits that bind 3H-Epibatidine with high affinity, and those containing the alpha7 subunit that bind 125I-alphaBungarotoxin. After postganglionic nerve crush, the number of nicotinic receptors and immunopositive intraganglionic synapses for each nAChR subunit strongly decreased. Both the number of nAChRs and immunoreactivity recovered 26 days after injury, when regenerating postganglionic fibers had reinnervated the peripheral target organs, as shown by the restoration of tyrosine hydroxylase immunoreactivity in the iris. This observation and the lack of any effect of preganglionic nerve crush on the number of nicotinic receptors suggest that the peripheral targets affect the organization of intraganglionic synapses in adult SCG.     

Gross morphology and morphometric sequelae in the hippocampus, fornix, and corpus callosum of patients with severe non-missile traumatic brain injury without macroscopically detectable lesions: a T1 weighted MRI study

OBJECTIVE: The gross morphology and morphometry of the hippocampus, fornix, and corpus callosum in patients with severe non-missile traumatic brain injury (nmTBI) without obvious neuroradiological lesions was examined and the volumes of these structures were correlated with performance on memory tests. In addition, the predictability of the length of coma from the selected anatomical volumes was examined. METHOD: High spatial resolution T1 weighted MRI scans of the brain (1 mm3) and neuropsychological evaluations with standardised tests were performed at least 3 months after trauma in 19 patients. RESULTS: In comparison with control subjects matched in terms of gender and age, volume reduction in the hippocampus, fornix, and corpus callosum of the nmTBI patients was quantitatively significant. The length of coma correlated with the volume reduction in the corpus callosum. Immediate free recall of word lists correlated with the volume of the fornix and the corpus callosum. Delayed recall of word lists and immediate recall of the Rey figure both correlated with the volume of the fornix. Delayed recall of the Rey figure correlated with the volume of the fornix and the right hippocampus. CONCLUSION: These findings demonstrate that in severe nmTBI without obvious neuroradiological lesions there is a clear hippocampal, fornix, and callosal volume reduction. The length of coma predicts the callosal volume reduction, which could be considered a marker of the severity of axonal loss. A few memory test scores correlated with the volumes of the selected anatomical structures. This relationship with memory performance may reflect the diffuse nature of the damage, leading to the disruption of neural circuits at multiple levels and the progressive neural degeneration occurring in TBI.     

Action observation and speech production: study on children and adults

The present study aimed to determine whether observation of upper limb actions selectively influences speech production. We compared the effects on children with those on adults, hypothesizing that action observation is used by children for speech learning. Children and adults observed an actor either grasping a cherry or an apple, or bringing the same fruits to his mouth. They pronounced the syllable/ba/ at the end of the action. In a control experiment, children and adults executed the two bringing-to-the-mouth actions, still pronouncing/ba/. As previously found ([Euro. J. Neurosci., 17 (2003) 179]; [Euro. J. Neurosci., 19 (2004) 192]), the observed kinematics of the action, which were different according to the fruit size, influenced lip shaping kinematics and voice formants. In addition, the effect was selective for the action since the observations of actions such as grasping and bringing-to-the-mouth affected formant 1 and formant 2 in the voice spectra, respectively. The effects on speech were greater in the children than in the adults. By contrast, the effects on lip shaping did not differ between the two groups. Effects similar to those found for action observation were found for action execution in spite of a different arm kinematics between children and adults. The results of the present study are discussed according to the hypothesis that action observation induces in the viewer action recognition and activation of the successive mouth act (probably grasping-with-the-mouth when observing grasping-with-the-hand and chewing when observing bringing-to-the-mouth). This subsequently seems to affect characteristics peculiar to the emitted vowel. This mechanism might have been used by humans to transfer a primitive arm gesture communication system from the arm to the mouth and may be further used by children for speech learning.     

Vogt-Koyanagi-Harada syndrome and keratoconjunctivitis sicca

PURPOSE: To discover a relationship between Vogt-Koyanagi-Harada (VKH) syndrome and Sj?gren syndrome. DESIGN: Observational case-control study. METHODS: Sixteen Italian patients with VKH syndrome and 16 controls with diffuse uveitis underwent tear analysis and rheumatologic evaluation. Biopsy specimens of the minor salivary glands were obtained or salivary gland scintigraphy was performed in patients with xerostomia. RESULTS: The Schirmer test (P <.0001), break-up time (P <.0001), the Ferning test (P <.001), and fluorescein and rose bengal staining (P <.0001) resulted in changes in VKH. Biopsy was positive in two patients and scintigraphy in four. Human leukocyte antigen DR4 was found in 68.75% of VKH cases and in 83.3% of the cases with Schirmer test less than 3 mm. CONCLUSIONS: The incidence of keratoconjunctivitis sicca was higher in VKH syndrome patients than in controls. Two patients satisfied the criteria for Sj?gren syndrome, and two others had scintigraphy indicative of salivary gland involvement. The association of these two autoimmune disorders is suggested by the low incidence of VKH syndrome in Italy and might be related to HLA DR4.     

"Induced-fit" mechanism for catecholamine binding to the beta2-adrenergic receptor

We engineered single and multiple mutations of serines 203, 204, and 207 in the fifth transmembrane domain of the beta(2)-adrenergic receptor, a region known to interact with hydroxyl groups of the catechol ring. Using such mutants, we measured the binding affinities of a panel of six catecholamine agonists differing only in the presence of substituents in the ethanolamine tail of the molecule. Although all ligands shared an intact catechol ring, they exhibited different losses of binding energy in response to the mutations. For all mutations, we found a clear relationship between the loss of binding caused by receptor mutation and that caused by the ligand modification. This indicates that the catechol ring and the ethanolamine tail synergistically influence their respective interactions when binding to the receptor. To verify this idea by a formal thermodynamic test, we used a double-mutant cycle analysis. We compared the effects of each receptor mutation with those induced by the modifications of the ligand's tail. Because such changes disrupt interactions occurring at different receptor domains, they should produce cumulative losses. In contrast, we found positive cooperativity between such effects. This means that the binding of each side of the catecholamine can enhance the binding of the other, through an effect that is probably propagated via a conformational change. We suggest that the agonist-binding pocket is not rigid but is dynamically formed as the ligand builds an increasing number of contacts with the receptor.     

5-Aminoisoquinolinone reduces colon injury by experimental colitis

Poly (ADP-ribose) polymerase (PARP), a nuclear enzyme activated by strand breaks in DNA, plays an important role in the colon injury associated with experimental colitis. The aim of the present study was to examine the effects of 5-aminoisoquinolinone (5-AIQ), a novel and potent inhibitor of PARP activity, in the development of experimental colitis. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). Compared with DNBS-treated mice, mice treated with 5-AIQ (3 mg/kg i.p.) or 3-aminobenzamide (3-AB; 10 mg/kg i.p. twice a day) and subjected to DNBS-induced colitis experienced a significantly lower rate in the extent and severity of the histological signs of colon injury. DNBS-treated mice experienced diarrhea and weight loss. Four days after administration of DNBS, the mucosa of the colon exhibited large areas of necrosis. Neutrophil infiltration (determined by histology as well as an increase in myeloperoxidase [MPO] activity in the mucosa) was associated with an up-regulation of intercellular adhesion molecule-1 (ICAM-1). Immunohistochemistry for PAR showed an intense staining in the inflamed colon. On the contrary, the treatment of DNBS-treated mice with 5-AIQ or with 3-AB significantly reduced the degree of hemorrhagic diarrhea and weight loss caused by administration of DNBS. 5-AIQ also caused a substantial reduction in the degree of colon injury, in the rise in MPO activity (mucosa), in the increase in staining (immunohistochemistry) for PAR, as well as in the up-regulation of ICAM-1 caused by DNBS in the colon. Thus, 5-AIQ treatment reduces the degree of colitis caused by DNBS. We propose that 5-AIQ treatment may be useful in the treatment of inflammatory bowel disease.     

Gramine: a vasorelaxing alkaloid acting on 5-HT(2A) receptors

The vascular effects of gramine on resistance vessels were evaluated, in particular as regards the 5-hydroxytryptamine (5-HT) system. We compared the action of gramine with that of ketanserin, a 5-HT (2A) antagonist; both compounds induced concentration-dependent relaxation in precontracted arterial rings. Also, the 5-HT concentration-effect curve shifted to the right in the presence of gramine, like ketanserin. These results suggest that gramine is a vasorelaxing agent acting mainly by antagonism at 5-HT (2A) receptors.