bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hypothyroidism Alters the Expression of Prostaglandin D2 Synthase/β‐ Trace in Specific Areas of the Developing Rat Brain
Authors: García‐Femández Luis F. , Rausell Estrella , Urade Yoshihiro , Hayaishi Osamu , Bernal Juan , Muñoz Alberto 
Published: April 2006

AbstractLipocalin‐type prostaglandin D2 synthase is the enzyme responsible for the synthesis of prostaglandin D2, a major prostaglandin in the central nervous system. We analysed the effects of thyroid hormone deprivation on prostaglandin D2 synthase gene expression in the developing rat brain. By in situ hybridization, the strongest prostaglandin D2 synthase mRNA signal was detected in the leptomeninges and choroid plexus. The signal was greatly reduced in the cerebellar interlaminar meninges of hypothyroid rats aged 15 and 25 days. lmmunohistochemical studies defined changes in the location of the prostaglandin D2 synthase protein. In control but not in hypothyroid animals, Cajal‐Retzius neurons of cortical layer 1, and pyramidal cortical plate neurons were intensely stained on postnatal day 5. Conversely, prostaglandin D2 synthase protein levels were higher in neurons of the CA1 and CA3 regions and the dentate gyrus of the hippocampus of hypothyroid animals on postnatal days 5, 15 and 25, and also in subplate neurons on postnatal days 15 and 25. In agreement with the in situ hybridization and northern blotting data, the major difference was found in the cerebellar interlaminar meninges of hypothyroid animals, where the protein was clearly down‐regulated on postnatal days 15 and 25. These results show that hypothyroidism causes both age‐ and region‐specific alterations in the expression and location of the prostaglandin D2 synthase during postnatal brain development, probably reflecting a cell‐specific regulatory effect of thyroid hormone on the prostaglandin D2 synthase.
Elimination of Motor Nerve Terminals in Neonatal Mice Expressing a Gene for Slow Wallerian Degeneration (C57Bl/Wlds)
Authors: Parson Simon H. , Mackintosh Claire L. , Ribchester Richard R. 
Published: April 2006

AbstractDegeneration of motor terminals after nerve section occurs much more slowly than normal in young adult mice of the C57BI/WldS strain. This observation prompted us to re‐examine the possible role of degeneration and intrinsic axon withdrawal during neonatal synapse elimination. Polyneuronal innervation was assayed by two methods: intracellular recording of end‐plate potentials in cut‐muscle fibre preparations of isolated hemidiaphragm and soleus muscles; and in silver‐stained preparations of triangularis sterni and transversus abdominis muscle fibres. No differences in the rate of synapse elimination were detected in unoperated Wlds compared with CBA, C3H/HE and BALB/c mice. At 3 days of age, >80% of fibres were polyneuronally innervated. By 7 days this declined to ∼20% of hemidiaphragm, 50% of triangularis sterni and 60% of soleus fibres. Nearly all fibres were mononeuronally innervated by 15 days. The mean number of terminals per triangularis sterni muscle fibre 7 days after birth was 1.55 ± 0.07 in Wlds and 1.56 ± 0.09 in wild‐type mice. Three to 4 days after sciatic nerve section, near‐normal numbers of motor units were evident in isometric tension recordings of the soleus muscle, and intracellular recordings revealed many polyneuronally innervated fibres. Mononeuronally and polyneuronally innervated fibres were also observed in silver‐stained preparations of soleus and transversus abdominis muscles made 3–4 days after sciatic or intercostal nerve section. We conclude (i) that the Wlds gene has no direct impact on the normal rate of postnatal synapse elimination, (ii) that Wallerian degeneration and synapse elimination must occur by distinct and different mechanisms, and (iii) that muscle fibres are able to sustain polyneuronal synaptic inputs even after motor axons have become disconnected from their cell bodies.
Learning‐induced Changes in Rat Piriform Cortex Activity Mapped Using Multisite Recording With Voltage Sensitive Dye
Authors: Litaudon Philippe , Mouly Anne‐Marie , Sullivan Regina , Gervais Remi , Cattarelli Martine 
Published: April 2006

AbstractThe piriform cortex (PCx) has a potential role in storage and recall of olfactory information. This study is a first extensive investigation of the spatiotemporal distribution of activity in the PCx induced by learned sensory inputs following conditioning. In a conditioned group, rats chronically implanted with four electrodes in the olfactory bulb were trained to associate the electrical stimulation of a given bulbar electrode with a positive reinforcement, while stimulation of a different electrode predicted a negative reinforcement. In a familiarized group, rats received the same protocol of daily electrical stimulation with no associated reinforcement. At the end of the conditioning or familiarization episode, activity evoked in the PCx was optically mapped using a 144 photodiode array. In the anaesthetized rats, PCx maps were recorded in response to stimulation of each of the four bulbar electrodes using either high (0.5–1 mA) or low (0.1 mA) test current intensities. Low intensity stimulation revealed that conditioning selectively enhanced the probability of occurrence of a signal composed of a single late (56–73 ms) component which occurred almost simultaneously on a large PCx area. In the conditioned group, high intensity stimulation through either of the four electrodes revealed a potentiation of the early (17–30 ms) disynaptic component of the PCx response in the most posterior part of the PCx as well as a homogeneous increase of the late (39–52 ms) component spread over the PCx areas. These data suggest that learning induces synaptic changes at different nodes of the PCx circuitry.
Short‐ and Long‐term Plasticity of the Hippocampus to Nucleus Accumbens and Prefrontal Cortex Pathways in the Rat, In Vivo
Authors: Mulder A. B. , Arts M. P. M. , da Silva F. H. Lopes 
Published: April 2006

AbstractThe pathways from the hippocampal formation to the nucleus accumbens and the prefrontal cortex are likely to play a role in several aspects of learning and memory. In the present study we addressed the question of how plastic changes in these structures may occur simultaneously. This question can be studied in an appropriate way in the hippocampaVfornix‐fimbria to prefrontal cortexhucleus accumbens system, since electrical stimulation of the fornix‐fimbria fibre bundle evokes characteristic field potentials in the two target areas simultaneously. First, we examined the termination field in the nucleus accumbens (medial shell and core region with an extension into the ventro‐medial caudate‐putamen) and the prefrontal cortex (deeper layers of the ventral prelimbic and ventral infralimbic areas) by recording single unit activity evoked by stimulation of fornix‐fimbria fibres in halothane anaesthetized rats. Second, we studied short‐term plasticity, namely paired pulse facilitation, in these two areas upon stimulation of the fornix‐fimbria fibres. In the nucleus accumbens, paired pulse facilitation was encountered for double pulse intervals between 25 and 500 ms, peaking around 100 ms. In the medial prefrontal cortex it was confined to intervals between 25 and 200 ms, with a peak around 75 ms. Third, we investigated whether LTP could be elicited simultaneously in the two target structures by a single tetanic stimulation (50 Hz, 2 s) of the fornix‐fimbria fibres. LTP that was sustained for more than 90 min in the medial prefrontal cortex, reached levels of 130% of control values. In the nucleus accumbens, however, only a transient form of potentiation was found which lasted no more than 60 min. These data show that synaptic weights can be changed in several target structures of the hippocampal formation, simultaneously, in a distributed way.
Sensory‐induced Plasticity of Motor Pattern Selection in the Lobster Stomatogastric Nervous System
Authors: Nargeot R. , Moulins M. 
Published: April 2006

AbstractIn a previous study, a bilateral sensory input pathway to the crustacean stomatogastric nervous system was reported to induce the functional switching of an identified motor neuron (VD) from one rhythm generating neural network (the pyloric circuit) to another (the cardiac sac network). In the present in vitro study on the spiny lobster, Palinurus vulgaris, we have shown that under certain conditions, repetitive trains of phasic stimulation (1 s; 40 Hz) of one of these sensory nerves elicits either an increase or a decrease in efficacy of the VD switching response. In preparations showing no previous sign either of increase or decrease in VD switching, either response can be induced by prior conditioning stimulation. The increasing effect can be induced by unpaired conditioning stimulation of the contralateral sensory nerve. Conversely, the decrease in switching efficacy is obtained by pairing stimulation of the sensory‐motor pathway with that applied to its contralateral partner. Both the experimentally induced increase and decrease in VD switching are long‐lasting, remaining observable for at least 20 min and in some cases up to 3 h after the original conditioning procedure. Our results suggest that this system provides a suitable ‘simple’ model for the analysis of experience‐related plasticity of the switching of a neuron from one network to another.
Differential Developmental Expression of the Two Rat Brain Glutamate Transporter Proteins GLAST and GLT
Authors: Ullensvang K. , Lehre K. P. , Storm‐Mathisen J. , Danbolt N. C. 
Published: April 2006

AbstractThe extracellular concentration of the excitatory neurotransmitter glutamate is kept low by the action of glutamate transporters in the plasma membranes of both neurons and glial cells. These transporters may play important roles, not only in the adult brain, but also in the developing brain, as glutamate is thought to modulate the formation and elimination of synapses as well as neuronal migration, proliferation and apoptosis. Here we demonstrate the developmental changes in the expression of two glutamate transporters, GLAST and GLT, by quantitative immunoblotting and by light and electron microscopic immunocytochemistry. At birth, GLT is not detectable, but GLAST is present at significant concentrations both in the forebrain and in the cerebellum. GLT is first detected in the forebrain and cerebellum in the second and third week, respectively. Both transporters reach adult levels by postnatal week 5. The development of the total glutamate uptake activity in the forebrain, as determined by solubilization and reconstitution of the transporters in liposomes, parallels that of GLT, in agreement with the observation that GLT is the predominant transporter in the adult brain. The regional distributions of both GLAST and GLT in the tissue are similar in young and adult rats. Only GLAST is detectable in the external germinal layer of the cerebellar cortex. Electron microscopical investigation demonstrated GLAST and GLT exclusively in glial cells in young as well as in adult animals.
Male Faces and Odours Evoke Differential Patterns of Neurochemical Release in the Mediobasal Hypothalamus of the Ewe During Oestrus: An Insight Into Sexual Motivation?
Authors: Fabre‐Nys Claude , Ohkura Satoshi , Kendrick Keith M. 
Published: April 2006

AbstractDuring behavioural oestrus female sheep, like females of many species, become both attracted to and sexually receptive towards males, whereas at other times they will avoid them. The mediobasal hypothalamus is the main site for the feedback action of sex steroids to induce sexual behaviour in the sheep and in previous studies we have shown that noradrenaline and serotonin are released in this region during sexual interactions with males. The current study investigated whether such changes are specific to interactions with males and if visual or olfactory cues or somatosensory stimulation during mating are critical. In vivo microdialysis sampling was carried out in the mediobasal hypothalamus of ovariectomized ewes submitted to artificial oestrous cycles. Release of monoamines and amino acid transmitters was first measured in animals during and after oestrus when they were exposed to interactions with either males or females or presentation of food. Noradrenaline concentrations only increased significantly when the females were in oestrus and interacted with males irrespective of whether intromissions were permitted. Females were then exposed to visual (faces) or odour (a home pen) cues from males or to the males themselves. Slide images of male faces increased concentrations of amines, glutamate and GABA during early oestrus, when females spent most time looking at them. During late oestrus noradrenaline, glutamate and GABA concentrations also increased in response to the male faces but no transmitter changes were seen during the luteal phase or at any time where the females were exposed to female faces, or inverted male faces. Exposure to male odour produced a lower increase in noradrenaline concentrations when females were in early oestrus but marked increases 20 and 30 min after exposure to male odours in late oestrus. No other transmitters were affected. Exposure to a male and mating with him when females were in early or late oestrus produced increased noradrenaline concentrations similar to those seen with face stimuli alone although other neurotransmitters were unaffected. These results show that noradrenaline, and to a lesser extent dopamine, serotonin, glutamate and GABA release in the mediobasal hypothalamus, can be modulated specifically in the oestrous female by sensory information coming from the male during oestrus. The differential effects of male cues during early and late oestrus suggest their involvement in (i) proceptive or anticipatory sexual responses shown by the female to male cues, and (ii) receptive sexual responses, and suggest that the mediobasal hypothalamus plays a key role in the integration of hormonal action on sexual motivation and processing of sensory information during oestrus.
Bone Morphogenetic Proteins: Neurotrophic Roles for Midbrain Dopaminergic Neurons and Implications of Astroglial Cells
Authors: Jordan Jens , Böttner Martina , Schluesener Hermann J. , Unsicker Klaus , Krieglstein Kerstin 
Published: April 2006

AbstractBone morphogenetic proteins (BMPs) are members of the transforming growth factor β (TGF‐β) superfamily that have been implicated in tissue growth and remodelling. Recent evidence suggests that several BMPs are expressed in the developing and adult brain. Specifically, we show that BMP 2 and BMP 6 are expressed in the developing midbrain floor of the rat. We studied potential neurotrophic effects of BMPs on the in vitro survival, transmitter uptake and protection against MPP+ toxicity of mesencephalic dopaminergic neurons cultured from the embryonic midbrain floor at embryonic day (E) 14. At 10 ng/ml and under serum‐free conditions, most BMPs promoted the survival of dopaminergic neurons visualized by tyrosine hydroxylase immunocytochemistry during an 8‐day culture period, but to varying extents (relative potencies: BMP 6 = 12 > 2, 4, 7). BMPs 6 and 12 were as effective as fibroblast growth factor‐2 (FGF‐2) and glial cell line‐derived neurotrophic factor, promoting survival 1.7‐fold compared with controls. BMPs 9 and 11 were not effective. Dose‐response curves revealed an EC50 for BMPs 2, 6 and 12 of 2 ng/ml. BMPs 2, 4, 6, 7, 9 and 12 also promoted DNA synthesis and astroglial cell differentiation, visualized by 5‐bromodeoxyuridine (BrdU) incorporation and glial fibrillary acidic protein (GFAP) immunocytochemistry respectively. Suppression of cell proliferation and subsequent maturation of GFAP‐positive cells by 5‐fluorodeoxyuridine or aminoadipic acid abolished the neuron survival‐promoting effect of BMP 2. This suggests that BMPs, like other non‐TGF‐β factors affecting dopaminergic neuron survival, act indirectly, probably by stimulating the synthesis and/or release of glial‐derived trophic factors. BMP 6 and BMP 7 also increased the uptake of [3H]dopamine without affecting the uptake of [3H]5‐hydroxytryptamine and [3H]GABA, underscoring the specificity of the trophic effect. We conclude that several BMPs share a neurotrophic capacity for dopaminergic midbrain neurons with other members of the TGF‐β superfamily, but act indirectly, possibly through glial cells.
Electrophysiological Evidence for Multiple Glycinergic Inputs to Neonatal Rat Sympathetic Preganglionic Neurons In Vitro
Authors: Krupp Johannes , Bordey Angélique , Feltz Paul 
Published: April 2006

AbstractThe time pattern of glycinergic inhibitory postsynaptic currents (IPSCs) in sympathetic preganglionic neurons was studied in thin transverse spinal cord slices of neonatal (1–10 days postnatal) rats by means of the patch‐clamp technique. Three time patterns could be distinguished: (i) large events [mostly >400 pA (30–36°C)] occurring at regular intervals, (ii) small events occurring at irregular intervals, and (iii) small events occurring in transient (1.5–10 s), high‐frequency (>15 Hz) bursts of synaptic activity. The large regular events had uniform kinetics which was consistent with the idea of a proximal site of origin for all of these events. They were reversibly inhibited in amplitude and frequency by extracellular application of a high concentration of acetylcholine (200 μM) or the specific nicotinic acetylcholine receptor agonist dimethylphenylpiperazinium iodide (DMPP; 1 mM), but unaffected by glutamate (100 μM). IPSCs occurring in bursts had slower and less uniform kinetics, suggesting a more diverse site of origin. The frequency of events decreased during a burst. Similar bursts could be induced by extracellular application of glutamate receptor agonists. These results indicate that sympathetic preganglionic neurons in a thin, transverse spinal cord slice receive at least two different glycinergic inputs.
Involvement of Activation of Dopamineraic Neuronal System in Learning and Memory Deficits Associated with Experimental Mild Traumatic Brain Injury
Authors: Tang Ya‐Ping , Noda Yukihiro , Nabeshima Toshitaka 
Published: April 2006

AbstractMuch evidence has indicated that a disturbance in dopamine neurotransmission following mild to moderate traumatic brain injury is involved in the development of post traumatic memory deficits. In the present study we examined the effects of a dopamine receptor agonist and some antagonists on latent learning and memory deficits associated with a concussive traumatic brain injury in mice. Anaesthetized animals were subjected to mild traumatic brain injury by dropping a weight onto the head, and a single‐dose injection of apomorphine (0.3–3.0 mg/kg) or haloperidol (0.3–3.0 mg/kg) was made i.p. 15 min after the trauma. One week later, a water‐finding task consisting of an acquisition trial, a retention test and a retest was employed to assess learning and memory functions. Mice that had received a traumatic brain injury were impaired in task performance, with prolonged latencies for finding and drinking in the retention test and retest. Administration of haloperidol but not of apomorphine significantly shortened the prolonged latency in both of the tests, indicating that antagonism of dopamine receptors is beneficial for the recovery of post traumatic memory deficits. In order to evaluate which receptor subtype plays the major role in this model, we examined the effects of SCH‐23390 (0.03–0.3 mg/kg), a D1 receptor antagonist, and sulpiride (3.0–30 mg/kg), a D2 receptor antagonist, in the same experimental paradigm. The results showed that administration of sulpiride but not of SCH‐23390 significantly improved the deficits in task performance, indicating that D2 receptors are the major site of action. However, combined treatment with SCH‐23390 (0.03–0.3 mg/kg) and sulpiride (3.0 mg/kg) at doses that had no effect when the antagonists were given alone exerted a significant additive effect in improving these deficits, indicating that interaction between D1 and D2 receptors is involved in these processes. The present results suggest that a dopaminergic mechanism contributes to the memory dysfunction associated with traumatic brain injury.
A Thalamic Contribution to Arousal‐induced, Non‐photic Entrainment of the Circadian Clock of the Syrian Hamster
Authors: Maywood Elizabeth S. , Smith Emma , Hall Stephanie J. , Hastings Michael H. 
Published: April 2006

AbstractIt is well established that the circadian clock of the suprachiasmatic nuclei (SCN) is entrained by light. More recently, the potent effects of arousing, non‐photic cues on the clock have been recognized. The neural mediators of non‐photic entrainment are yet to be identified. To examine the contribution of the thalamic intergeniculate leaflet (IGL) and its NPY‐immunopositive projection, the geniculo‐hypothalamic tract to non‐photic entrainment by arousal, male Syrian hamsters received lesions of the IGL (IGLX) which ablated NPY‐immunoreactivity in the SCN. Their circadian responses to both photic and non‐photic cues were then tested. Lesions resulted in a delay in the timing of activity onset following lights out, but had no effect on the behavioural or cellular circadian responses to phase‐advancing light pulses presented at circadian time (CT) CT19 (where CT12 represents the time of activity onset). Injection with a benzodiazepine (chlordiazepoxide, 100 mg/kg) at CT6 suppressed wheel‐running, increased general locomotion of intact controls and induced large phase advances of the circadian rhythm of wheel‐running. Chlordiazepoxide also inhibited wheel‐running in lesioned animals, but there was no significant increase in general locomotion and the lesioned animals did not phase advance. Serial arousal by injection of saline at intervals of 23.5 h for 6 days entrained the circadian rhythm of wheel‐running of intact hamsters and was associated with an increase in general locomotor activity. Entrainment by serial arousal was abolished by IGLX. However, the lesioned animals did show a clear behavioural response to every presentation of the non‐photic cue. These results show that the IGL is a necessary component of the neural pathways mediating both arousal‐ and benzodiazepine‐induced non‐photic entrainment.
Glycosaminoglycan Supplementation Promotes Nerve Regeneration and Muscle Reinnervation
Authors: Gorio A. , Lesma E. , Vergani L. , Di Giulio A. M. 
Published: April 2006

AbstractThis study shows that treatment of rats with exogenous glycosaminoglycans stimulates peripheral nerve regeneration, increases the abundance of mRNAs for myelin proteins and promotes muscle reinnervation. After the sciatic nerve had been crushed the number of regenerating axons in the distal stump was markedly and highly significantly increased by glycosaminoglycan treatment throughout the experimental period. The increased number of axons was correlated with increased axon and fibre (axon + myelin) diameter. The abundance of mRNAs for Po protein and myelin basic protein of regenerating nerves was also affected by treatment with glycosaminoglycans. The increase in mRNA was also observed in the contralateral unlesioned nerve. Such a phenomenon did not occur in saline‐treated rats. Glycosaminoglycan treatment markedly increased the number of muscle fibres reinnervated and accelerated the restoration of muscle twitch tension elicited by nerve stimulation. The effect was particularly evident during the early stages (16 and 21 days after nerve crush) of muscle reinnervation.