RESUMO
The Phospholipid Phosphatase Related 4 gene (PLPPR4, *607813) encodes the Plasticity-Related-Gene-1 (PRG-1) protein. This cerebral synaptic transmembrane-protein modulates cortical excitatory transmission on glutamatergic neurons. In mice, homozygous Prg-1 deficiency causes juvenile epilepsy. Its epileptogenic potential in humans was unknown. Thus, we screened 18 patients with infantile epileptic spasms syndrome (IESS) and 98 patients with benign familial neonatal/infantile seizures (BFNS/BFIS) for the presence of PLPPR4 variants. A girl with IESS had inherited a PLPPR4-mutation (c.896C > G, NM_014839; p.T299S) from her father and an SCN1A-mutation from her mother (c.1622A > G, NM_006920; p.N541S). The PLPPR4-mutation was located in the third extracellular lysophosphatidic acid-interacting domain and in-utero electroporation (IUE) of the Prg-1p.T300S construct into neurons of Prg-1 knockout embryos demonstrated its inability to rescue the electrophysiological knockout phenotype. Electrophysiology on the recombinant SCN1Ap.N541S channel revealed partial loss-of-function. Another PLPPR4 variant (c.1034C > G, NM_014839; p.R345T) that was shown to result in a loss-of-function aggravated a BFNS/BFIS phenotype and also failed to suppress glutamatergic neurotransmission after IUE. The aggravating effect of Plppr4-haploinsufficiency on epileptogenesis was further verified using the kainate-model of epilepsy: double heterozygous Plppr4-/+|Scn1awt|p.R1648H mice exhibited higher seizure susceptibility than either wild-type, Plppr4-/+, or Scn1awt|p.R1648H littermates. Our study shows that a heterozygous PLPPR4 loss-of-function mutation may have a modifying effect on BFNS/BFIS and on SCN1A-related epilepsy in mice and humans.
Assuntos
Epilepsia , Convulsões , Animais , Feminino , Humanos , Camundongos , Epilepsia/metabolismo , Hipocampo/metabolismo , Mutação/genética , Canal de Sódio Disparado por Voltagem NAV1.1/genética , Fenótipo , Convulsões/genética , Convulsões/metabolismoRESUMO
Both humans and animals seek primary rewards in the environment, even when such rewards do not correspond to current physiological needs. An example of this is a dissociation between food-seeking behaviour and metabolic needs, a notoriously difficult-to-treat symptom of eating disorders. Feeding relies on distinct cell groups in the hypothalamus, the activity of which also changes in anticipation of feeding onset. The hypothalamus receives strong descending inputs from the lateral septum, which is connected, in turn, with cortical networks, but cognitive regulation of feeding-related behaviours is not yet understood. Cortical cognitive processing involves gamma oscillations, which support memory, attention, cognitive flexibility and sensory responses. These functions contribute crucially to feeding behaviour by unknown neural mechanisms. Here we show that coordinated gamma (30-90 Hz) oscillations in the lateral hypothalamus and upstream brain regions organize food-seeking behaviour in mice. Gamma-rhythmic input to the lateral hypothalamus from somatostatin-positive lateral septum cells evokes food approach without affecting food intake. Inhibitory inputs from the lateral septum enable separate signalling by lateral hypothalamus neurons according to their feeding-related activity, making them fire at distinct phases of the gamma oscillation. Upstream, medial prefrontal cortical projections provide gamma-rhythmic inputs to the lateral septum; these inputs are causally associated with improved performance in a food-rewarded learning task. Overall, our work identifies a top-down pathway that uses gamma synchronization to guide the activity of subcortical networks and to regulate feeding behaviour by dynamic reorganization of functional cell groups in the hypothalamus.
Assuntos
Comportamento Alimentar/fisiologia , Ritmo Gama/fisiologia , Hipotálamo/fisiologia , Animais , Ingestão de Alimentos/fisiologia , Ingestão de Alimentos/psicologia , Metabolismo Energético/fisiologia , Comportamento Alimentar/psicologia , Hipotálamo/citologia , Aprendizagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/fisiologia , Recompensa , Somatostatina/metabolismoRESUMO
The anatomical and functional mapping of lateral hypothalamic circuits has been limited by the numerous cell types and complex, yet unclear, connectivity. Recent advances in functional dissection of input-output neurons in the lateral hypothalamus have identified subset of inhibitory cells as crucial modulators of both sleep-wake states and metabolism. Here, we summarize these recent studies and discuss the multi-tasking functions of hypothalamic circuitries in integrating sleep and metabolism in the mammalian brain.
Assuntos
Região Hipotalâmica Lateral/fisiologia , Metabolismo/fisiologia , Sono/fisiologia , Animais , Nível de Alerta/fisiologia , HumanosRESUMO
STX1 is a major neuronal syntaxin protein located at the plasma membrane of the neuronal tissues. Rodent STX1 has two highly similar paralogs, STX1A and STX1B, that are thought to be functionally redundant. Interestingly, some studies have shown that the distribution patterns of STX1A and STX1B at the central and peripheral nervous systems only partially overlapped, implying that there might be differential functions between these paralogs. In the current study, we generated an STX1B knockout (KO) mouse line and studied the impact of STX1B removal in neurons of several brain regions and the neuromuscular junction (NMJ). We found that either complete removal of STX1B or selective removal of it from forebrain excitatory neurons in mice caused premature death. Autaptic hippocampal and striatal cultures derived from STX1B KO mice still maintained efficient neurotransmission compared with neurons from STX1B wild-type and heterozygous mice. Interestingly, examining high-density cerebellar cultures revealed a decrease in the spontaneous GABAergic transmission frequency, which was most likely due to a lower number of neurons in the STX1B KO cultures, suggesting that STX1B is essential for neuronal survival in vitro. Moreover, our study also demonstrated that although STX1B is dispensable for the formation of the mouse NMJ, it is required to maintain the efficiency of neurotransmission at the nerve-muscle synapse.
Assuntos
Encéfalo/fisiopatologia , Junção Neuromuscular/fisiologia , Neurônios/fisiologia , Sintaxina 1/metabolismo , Animais , Western Blotting , Encéfalo/patologia , Sobrevivência Celular/fisiologia , Células Cultivadas , Morte , Potenciais Pós-Sinápticos Excitadores/fisiologia , Imuno-Histoquímica , Potenciais Pós-Sinápticos Inibidores/fisiologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Confocal , Potenciais Pós-Sinápticos em Miniatura/fisiologia , Proteínas Munc18/metabolismo , Neurônios/patologia , Técnicas de Patch-Clamp , Sintaxina 1/genética , Ácido gama-Aminobutírico/metabolismoRESUMO
Innate behaviors meet multiple needs adaptively and in a serial order, suggesting the existence of a hitherto elusive brain dynamics that brings together representations of upcoming behaviors during their selection. Here we show that during behavioral transitions, possible upcoming behaviors are encoded by specific signatures of neuronal populations in the lateral hypothalamus (LH) that are active near beta oscillation peaks. Optogenetic recruitment of intrahypothalamic inhibition at this phase eliminates behavioral transitions. We show that transitions are elicited by beta-rhythmic inputs from the prefrontal cortex that spontaneously synchronize with LH 'transition cells' encoding multiple behaviors. Downstream of the LH, dopamine neurons increase firing during beta oscillations and also encode behavioral transitions. Thus, a hypothalamic transition state signals alternative future behaviors, encodes the one most likely to be selected and enables rapid coordination with cognitive and reward-processing circuitries, commanding adaptive social contact and eating behaviors.
Assuntos
Ritmo beta , Vias Neurais , Córtex Pré-Frontal , Animais , Córtex Pré-Frontal/fisiologia , Vias Neurais/fisiologia , Masculino , Ritmo beta/fisiologia , Camundongos , Optogenética , Comportamento Animal/fisiologia , Região Hipotalâmica Lateral/fisiologia , Recompensa , Neurônios Dopaminérgicos/fisiologia , Hipotálamo/fisiologiaRESUMO
Animals continuously weigh hunger and thirst against competing needs, such as social contact and mating, according to state and opportunity. Yet neuronal mechanisms of sensing and ranking nutritional needs remain poorly understood. Here, combining calcium imaging in freely behaving mice, optogenetics, and chemogenetics, we show that two neuronal populations of the lateral hypothalamus (LH) guide increasingly hungry animals through behavioral choices between nutritional and social rewards. While increased food consumption was marked by increasing inhibition of a leptin receptor-expressing (LepRLH) subpopulation at a fast timescale, LepRLH neurons limited feeding or drinking and promoted social interaction despite hunger or thirst. Conversely, neurotensin-expressing LH neurons preferentially encoded water despite hunger pressure and promoted water seeking, while relegating social needs. Thus, hunger and thirst gate both LH populations in a complementary manner to enable the flexible fulfillment of multiple essential needs.
Assuntos
Fome , Região Hipotalâmica Lateral , Camundongos , Animais , Região Hipotalâmica Lateral/fisiologia , Fome/fisiologia , Neurônios/fisiologia , NeurotensinaRESUMO
OBJECTIVE: Small arteries from different organs vary with regard to the mechanisms that regulate vasoconstriction. This study investigated the impact of advanced age on the regulation of vasoconstriction in isolated human small arteries from kidney cortex and periintestinal mesenteric tissue. METHODS: Renal and mesenteric tissues were obtained from patients (mean age 71â±â9âyears) undergoing elective surgery. Furthermore, intrarenal and mesenteric arteries from young and aged mice were studied. Arteries were investigated by small vessel myography and western blot. RESULTS: Human intrarenal arteries (h-RA) showed higher stretch-induced tone and higher reactivity to α 1 adrenergic receptor stimulation than human mesenteric arteries (h-MA). Rho-kinase (ROK) inhibition resulted in a greater decrease in Ca 2+ and depolarization-induced tone in h-RA than in h-MA. Basal and α 1 adrenergic receptor stimulation-induced phosphorylation of the regulatory light chain of myosin (MLC 20 ) was higher in h-RA than in h-MA. This was associated with higher ROK-dependent phosphorylation of the regulatory subunit of myosin light-chain-phosphatase (MLCP), MYPT1-T853. In h-RA phosphorylation of ribosomal S6-kinase II (RSK2-S227) was significantly higher than in h-MA. Stretch-induced tone and RSK2 phosphorylation was also higher in interlobar arteries (m-IAs) from aged mice than in respective vessels from young mice and in murine mesenteric arteries (m-MA) from both age groups. CONCLUSION: Vasoconstriction in human intrarenal arteries shows a greater ROK-dependence than in mesenteric arteries. Activation of RSK2 may contribute to intrarenal artery tone dysregulation associated with aging. Compared with h-RA, h-MA undergo age-related remodeling leading to a reduction of the contractile response to α 1 adrenergic stimulation.
Assuntos
Receptores Adrenérgicos alfa 1 , Quinases Associadas a rho , Humanos , Camundongos , Animais , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Quinases Associadas a rho/metabolismo , Receptores Adrenérgicos alfa 1/metabolismo , Artérias Mesentéricas/metabolismo , Transdução de Sinais , Vasoconstrição , Miosinas/metabolismo , Fosforilação , Fosfatase de Miosina-de-Cadeia-Leve/metabolismoRESUMO
Cannabis consumption results in impaired learning. The proper synchronization of neuronal activity in the mammalian hippocampus gives rise to network rhythms that are implicated in memory formation. Here, we have studied the impact of cannabinoids on hippocampal sharp waves and associated ripple oscillations using field- and whole-cell voltage-clamp recordings. We demonstrate that the activation of cannabinoid receptor 1 suppresses sharp wave-ripples (SWRs) in mice in vivo and in vitro. This suppression was paralleled by a selective reduction of SWR-associated inward but not outward charge transfer, demonstrating an impairment of excitation due to cannabinoid exposure. Adenosine, a presynaptic modulator of glutamate release, mimicked and occluded the observed consequences of cannabinoids on SWRs. We conclude that inhibition of glutamatergic feed-forward excitation can explain cannabinoid-mediated disruption of SWRs and may account for cannabinoid-induced impairment of hippocampus-dependent memory.
Assuntos
Canabinoides/farmacologia , Ácido Glutâmico/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Inibição Neural/efeitos dos fármacos , Inibição Neural/fisiologia , Animais , Cicloexanóis/farmacologia , Relação Dose-Resposta a Droga , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Rede Nervosa/efeitos dos fármacos , Rede Nervosa/metabolismo , Receptor CB1 de Canabinoide/agonistas , Receptor CB1 de Canabinoide/metabolismoRESUMO
Hippocampal theta (5-10 Hz) and gamma (35-85 Hz) oscillations depend on an inhibitory network of GABAergic interneurons. However, the lack of methods for direct and cell-type-specific interference with inhibition has prevented better insights that help link synaptic and cellular properties with network function. Here, we generated genetically modified mice (PV-Deltagamma(2)) in which synaptic inhibition was ablated in parvalbumin-positive (PV+) interneurons. Hippocampal local field potential and unit recordings in the CA1 area of freely behaving mice revealed that theta rhythm was strongly reduced in these mice. The characteristic coupling of theta and gamma oscillations was strongly altered in PV-Deltagamma(2) mice more than could be accounted for by the reduction in theta rhythm only. Surprisingly, gamma oscillations were not altered. These data indicate that synaptic inhibition onto PV+ interneurons is indispensable for theta- and its coupling to gamma oscillations but not for rhythmic gamma-activity in the hippocampus. Similar alterations in rhythmic activity were obtained in a computational hippocampal network model mimicking the genetic modification, suggesting that intrahippocampal networks might contribute to these effects.
Assuntos
Hipocampo/efeitos dos fármacos , Interneurônios/efeitos dos fármacos , Parvalbuminas/farmacologia , Animais , Comportamento Animal , Eletrofisiologia , Hipocampo/metabolismo , Interneurônios/metabolismo , Camundongos , Modelos Neurológicos , Técnicas de Patch-Clamp , Subunidades Proteicas/metabolismo , Receptores de GABA-A/metabolismo , Sinapses/efeitos dos fármacos , Sinapses/metabolismo , Ritmo Teta , Fatores de TempoRESUMO
PURPOSE: Exogenously administered mesenchymal stem cells and bioactive molecules are known to enhance tendon healing. Biomolecules have been successfully delivered using sutures that elute growth factors over time. We sought to evaluate the histologic and biomechanical effect of delivering both cells and bioactive substrates on a suture delivery vehicle in comparison with sutures coated with bioactive substrates alone. METHODS: Bone marrow-derived stem cells were harvested from Sprague-Dawley rat femurs. Experimental cell and substrate-coated, coated suture (CS) group sutures were precoated with intercellular cell adhesion molecule 1 and poly-L-lysine and seeded with labeled bone marrow-derived stem cells. Control (substrate-only [SO] coated) group sutures were coated with intercellular cell adhesion molecule 1 and poly-L-lysine only. Using a matched-paired design, bilateral Sprague-Dawley rat Achilles tendons (n = 105 rats) were transected and randomized to CS or SO repairs. Tendons were harvested at 4, 7, 10, 14, and 28 days and subjected to histologic and mechanical assessment. RESULTS: Labeled cells were present at repair sites at all time points. The CS suture repairs displayed statistically greater strength compared to SO repairs at 7 days (12.6 ± 5.0 N vs 8.6 ± 3.7 N, respectively) and 10 days (21.2 ± 4.9 N vs 16.4 ± 4.8 N, respectively). There was no significant difference between the strength of CS suture repairs compared with SO repairs at 4 days (8.1 ± 5.1 N vs 6.6 ± 2.3 N, respectively), 14 days (22.8 ± 7.3 N vs 25.1 ± 9.7 N, respectively), and 28 days (40.9 ± 12.4 N vs 34.6 ± 15.0 N, respectively). CONCLUSIONS: Bioactive CS sutures enhanced repair strength at 7 to 10 days. There was no significant effect at later stages. CLINICAL RELEVANCE: The strength nadir of a tendon repair occurs in the first 2 weeks after surgery. Bioactive suture repair might provide a clinical advantage by jump-starting the repair process during this strength nadir. Improved early strength might, in turn allow earlier unprotected mobilization.
Assuntos
Molécula 1 de Adesão Intercelular/farmacologia , Células-Tronco Mesenquimais , Polietilenoglicóis/farmacologia , Polilisina/análogos & derivados , Suturas , Tendões/cirurgia , Cicatrização/fisiologia , Animais , Distribuição de Qui-Quadrado , Materiais Revestidos Biocompatíveis , Modelos Animais de Doenças , Masculino , Polilisina/farmacologia , Distribuição Aleatória , Ratos , Ratos Sprague-DawleyRESUMO
PURPOSE: We evaluated the fate of pluripotential stem cells adherent to a suture carrier after being passed through tendon tissue in vitro. METHODS: FiberWire suture segments were coated with poly-L-lysine (PLL) and a 2 × 10(6) C3H10T1/2 (a mouse embryo pluripotential cell line) cell suspension. The sutures were incubated for 7 days, passed through two 1-cm segments of acellularized rabbit Achilles tendons and tied (horizontal mattress). The repairs were frozen and sectioned (6 µm). The sections were stained with 4',6-diamidino-2-phenylindole and a live/dead viability/cytotoxicity (calcein/ethidium homodimer) kit and examined with fluorescent microscopy to evaluate cell presence and viability. Alamar Blue was used in parallel to assess metabolic activity. RESULTS: PLL-coated sutures showed a 3-fold increase in fluorescence when compared with the phosphate-buffered saline-coated controls. At day 3, fluorescence was 2.2 times greater. At day 5, a 2-fold increase was found, and at day 8 there was no significant difference in values. Furthermore, after delivery of the cells into tendon, fluorescence readings for the samples (n = 19) showed 9450 compared with the positive control at 21,218. At 96 hours the mean was 27,609 compared with 34,850 for the positive control. The difference in fluorescence means at 48 hours and 96 hours were significant (p < .001). Live-dead and DAPI staining confirmed the presence of live cells at the tendon repair site. CONCLUSIONS: Sutures seeded with pluripotential embryonic cells deliver cells to a tendon repair site. The cells deposited at the repair site survive the trauma of passage and remain metabolically active, as seen in staining and metabolic assay studies. Use of bioactive sutures leads to repopulation of the acellular zone surrounding sutures within the tendon.
Assuntos
Tendão do Calcâneo/cirurgia , Proliferação de Células , Células-Tronco Pluripotentes/transplante , Suturas , Animais , Materiais Revestidos Biocompatíveis , Corantes Fluorescentes , Indóis , Microscopia de Fluorescência , Modelos Animais , Coelhos , Transplante de Células-Tronco/métodos , Técnicas de Sutura , Resistência à Tração , Coleta de Tecidos e ÓrgãosRESUMO
Hippocampal pyramidal cells encode an animal's location by single action potentials and complex spike bursts. These elementary signals are believed to play distinct roles in memory consolidation. The timing of single spikes and bursts is determined by intrinsic excitability and theta oscillations (5-10 Hz). Yet contributions of these dynamics to place fields remain elusive due to the lack of methods for specific modification of burst discharge. In mice lacking Kcnq3-containing M-type K+ channels, we find that pyramidal cell bursts are less coordinated by the theta rhythm than in controls during spatial navigation, but not alert immobility. Less modulated bursts are followed by an intact post-burst pause of single spike firing, resulting in a temporal discoordination of network oscillatory and intrinsic excitability. Place fields of single spikes in one- and two-dimensional environments are smaller in the mutant. Optogenetic manipulations of upstream signals reveal that neither medial septal GABA-ergic nor cholinergic inputs alone, but rather their joint activity, is required for entrainment of bursts. Our results suggest that altered representations by bursts and single spikes may contribute to deficits underlying cognitive disabilities associated with KCNQ3-mutations in humans.
Assuntos
Potenciais de Ação/fisiologia , Canal de Potássio KCNQ3/fisiologia , Células Piramidais/fisiologia , Ritmo Teta/fisiologia , Animais , Hipocampo/citologia , Humanos , Canal de Potássio KCNQ3/genética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Optogenética/métodosRESUMO
Subthalamic nucleus (STN) is the main source of feed-forward excitation in the basal ganglia and a main target of therapeutic deep brain stimulation in movement disorders. Alleviation of motor symptoms during STN stimulation can be accompanied by deterioration of abilities to quickly choose between conflicting alternatives. Cortical afferents to the subthalamic region (ST), comprising STN and zona incerta (ZI), include projections from the medial prefrontal cortex (mPFC), yet little is known about prefrontal-subthalamic coordination and its relevance for decision-making. Here we combined electrophysiological recordings with optogenetic manipulations of projections from mPFC to ST in mice as they performed a spatial working memory task (T-maze) or explored an elevated plus maze (anxiety test). We found that gamma oscillations (30-70 Hz) are coordinated between mPFC and ST at theta (5-10 Hz) and, less efficiently, at sub-theta (2-5 Hz) frequencies. An optogenetic detuning of the theta/gamma cross-frequency coupling between the regions into sub-theta range impaired performance in the T-maze, yet did not affect anxiety-related behaviors in the elevated plus maze. Both detuning and inhibition of the mPFC-ST pathway led to repeated incorrect choices in the T-maze. These effects were not associated with changes of anxiety and motor activity measures. Our findings suggest that action selection in a cognitively demanding task crucially involves theta rhythmic coordination of gamma oscillatory signaling in the prefrontal-subthalamic pathway.
Assuntos
Memória de Curto Prazo/fisiologia , Córtex Pré-Frontal/fisiologia , Memória Espacial/fisiologia , Núcleo Subtalâmico/fisiologia , Animais , Ritmo Gama/fisiologia , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Optogenética/métodos , Ritmo Teta/fisiologiaRESUMO
Calorie-rich diets induce hyperphagia and promote obesity, although the underlying mechanisms remain poorly defined. We find that short-term high-fat-diet (HFD) feeding of mice activates prepronociceptin (PNOC)-expressing neurons in the arcuate nucleus of the hypothalamus (ARC). PNOCARC neurons represent a previously unrecognized GABAergic population of ARC neurons distinct from well-defined feeding regulatory AgRP or POMC neurons. PNOCARC neurons arborize densely in the ARC and provide inhibitory synaptic input to nearby anorexigenic POMC neurons. Optogenetic activation of PNOCARC neurons in the ARC and their projections to the bed nucleus of the stria terminalis promotes feeding. Selective ablation of these cells promotes the activation of POMC neurons upon HFD exposure, reduces feeding, and protects from obesity, but it does not affect food intake or body weight under normal chow consumption. We characterize PNOCARC neurons as a novel ARC neuron population activated upon palatable food consumption to promote hyperphagia.
Assuntos
Núcleo Arqueado do Hipotálamo/fisiologia , Dieta Hiperlipídica , Comportamento Alimentar/fisiologia , Neurônios GABAérgicos/fisiologia , Hiperfagia , Obesidade , Aumento de Peso/fisiologia , Animais , Núcleo Arqueado do Hipotálamo/citologia , Núcleo Arqueado do Hipotálamo/metabolismo , Neurônios GABAérgicos/metabolismo , Camundongos , Inibição Neural/fisiologia , Neurônios/metabolismo , Neurônios/fisiologia , Optogenética , Pró-Opiomelanocortina/metabolismo , Precursores de Proteínas/metabolismo , Receptores Opioides/metabolismo , Núcleos Septais/fisiologiaRESUMO
Variations in the human FTO gene have been linked to obesity and altered connectivity of the dopaminergic neurocircuitry. Here, we report that fat mass and obesity-associated protein (FTO) in dopamine D2 receptor-expressing medium spiny neurons (D2 MSNs) of mice regulate the excitability of these cells and control their striatopallidal globus pallidus external (GPe) projections. Lack of FTO in D2 MSNs translates into increased locomotor activity to novelty, associated with altered timing behavior, without impairing the ability to control actions or affecting reward-driven and conditioned behavior. Pharmacological manipulations of dopamine D1 receptor (D1R)- or D2R-dependent pathways in these animals reveal altered responses to D1- and D2-MSN-mediated control of motor output. These findings reveal a critical role for FTO to control D2 MSN excitability, their projections to the GPe, and behavioral responses to novelty.
Assuntos
Dioxigenase FTO Dependente de alfa-Cetoglutarato/metabolismo , Neurônios Dopaminérgicos/metabolismo , Comportamento Exploratório , Locomoção , Potenciais de Ação , Dioxigenase FTO Dependente de alfa-Cetoglutarato/genética , Animais , Neurônios Dopaminérgicos/fisiologia , Feminino , Globo Pálido/citologia , Globo Pálido/metabolismo , Globo Pálido/fisiologia , Masculino , Camundongos , Receptores de Dopamina D1/genética , Receptores de Dopamina D1/metabolismo , Receptores de Dopamina D2/genética , Receptores de Dopamina D2/metabolismo , RecompensaRESUMO
The synchronization of neuronal networks may be instrumental in plasticity and learning. Hippocampal high-frequency oscillations (140-200 Hz, 'ripples') characteristic of consummatory behaviours are thought to promote memory formation. We recorded ripple oscillations from the CA1 area in temporal learning tasks. Rats learned to adjust their operant response to the timing of food reward delivery [fixed interval schedule (FI)]. The intrinsic frequency of ripples was elevated following the switch in reinforcement timing. Learning, as assessed from the response pattern, correlated with fluctuations of intraripple frequency and amplitude. Changes in motor activity did not account for the variability of ripple oscillations. At the same time, features of ripples were unaltered when the fixed interval of reward delivery was changed but did not depend on the lever press response. Thus, in addition to the known replay of neuronal firing patterns during ripple oscillations, the rhythm itself appears to be modulated in an experience-specific way and represents a direct correlate of learning.
Assuntos
Relógios Biológicos/fisiologia , Sincronização Cortical , Hipocampo/fisiologia , Aprendizagem/fisiologia , Rede Nervosa/fisiologia , Potenciais de Ação/fisiologia , Animais , Condicionamento Operante/fisiologia , Hipocampo/anatomia & histologia , Masculino , Memória/fisiologia , Rede Nervosa/anatomia & histologia , Vias Neurais/anatomia & histologia , Vias Neurais/fisiologia , Neurônios/fisiologia , Testes Neuropsicológicos , Ratos , Ratos Wistar , Recompensa , Fatores de Tempo , Percepção do Tempo/fisiologiaRESUMO
PURPOSE: Pluripotential embryonic cells may be seeded onto sutures intended for tendon repair. These cells may be influenced to adhere to suture material using adhesion substrates, and furthermore, these cells may remain in culture attached to those sutures. These cell-impregnated sutures may be useful for promoting healing of tendon repairs. METHODS: Ten-centimeter segments of 4-0 sutures (FiberWire) were coated overnight with 10 microg/mL fibronectin, 10 microg/mL poly-l-lysine, or phosphate-buffered saline. The sutures were placed in dishes and covered with a suspension of C3H10T1/2 cells at concentrations of 1 x 10(6), 2 x 10(6), or 4 x 10(6) cells for 24 hours. The sutures were then placed into low adhesion polypropylene tubes with Dulbecco's modified Eagle's medium and 10% fetal bovine serum for 7 days. The presence of viable cells on these sutures was assessed by the colorimetric Alamar blue cell proliferation assay. Spectrophotometry was used to quantify the relative amount of cell proliferation across the experimental groups. The sutures were also visually inspected using phase-contrast light microscopy. RESULTS: Our results show that at all seeding densities (1 x 10(6), 2 x 10(6), and 4 x 10(6) cells), the suture segments coated with poly-l-lysine and fibronectin showed a significant increase in C3H10T1/2 cell adhesion. Coating the suture with poly-l-lysine increased the adherent cell number to 17% of the initial seeding concentration compared with 2% for the control. Fibronectin coating increased the number of adherent viable cells present to 6.6%. CONCLUSIONS: Pluripotential embryonic cells may be seeded onto sutures, adhere, and survive in culture. Coating sutures with poly-l-lysine and fibronectin offers significant improvement in retention of viable cells. This technique may be a useful adjunct for future tendon healing studies.
Assuntos
Materiais Revestidos Biocompatíveis , Células-Tronco Embrionárias , Células-Tronco Pluripotentes , Suturas , Traumatismos dos Tendões/terapia , Animais , Adesão Celular , Fibronectinas , PolilisinaRESUMO
Extensive data on relationships of neural network oscillations to behavior and organization of neuronal discharge across brain regions call for new tools to selectively manipulate brain rhythms. Here we describe an approach combining projection-specific optogenetics with extracellular electrophysiology for high-fidelity control of hippocampal theta oscillations (5-10 Hz) in behaving mice. The specificity of the optogenetic entrainment is achieved by targeting channelrhodopsin-2 (ChR2) to the GABAergic population of medial septal cells, crucially involved in the generation of hippocampal theta oscillations, and a local synchronized activation of a subset of inhibitory septal afferents in the hippocampus. The efficacy of the optogenetic rhythm control is verified by a simultaneous monitoring of the local field potential (LFP) across lamina of the CA1 area and/or of neuronal discharge. Using this readily implementable preparation we show efficacy of various optogenetic stimulation protocols for induction of theta oscillations and for the manipulation of their frequency and regularity. Finally, a combination of the theta rhythm control with projection-specific inhibition addresses the readout of particular aspects of the hippocampal synchronization by efferent regions.
Assuntos
Hipocampo/patologia , Optogenética/métodos , Animais , CamundongosRESUMO
The theta oscillation (5-10Hz) is a prominent behavior-specific brain rhythm. This review summarizes studies showing the multifaceted role of theta rhythm in cognitive functions, including spatial coding, time coding and memory, exploratory locomotion and anxiety-related behaviors. We describe how activity of hippocampal theta rhythm generators - medial septum, nucleus incertus and entorhinal cortex, links theta with specific behaviors. We review evidence for functions of the theta-rhythmic signaling to subcortical targets, including lateral septum. Further, we describe functional associations of theta oscillation properties - phase, frequency and amplitude - with memory, locomotion and anxiety, and outline how manipulations of these features, using optogenetics or pharmacology, affect associative and innate behaviors. We discuss work linking cognition to the slope of the theta frequency to running speed regression, and emotion-sensitivity (anxiolysis) to its y-intercept. Finally, we describe parallel emergence of theta oscillations, theta-mediated neuronal activity and behaviors during development. This review highlights a complex interplay of neuronal circuits and synchronization features, which enables an adaptive regulation of multiple behaviors by theta-rhythmic signaling.