Search results for "Postsynaptic potential"

Tyramine action on motoneuron excitability and adaptable tyramine/octopamine ratios adjust Drosophila locomotion to nutritional state

2019

Adrenergic signaling profoundly modulates animal behavior. For example, the invertebrate counterpart of norepinephrine, octopamine, and its biological precursor and functional antagonist, tyramine, adjust motor behavior to different nutritional states. In Drosophila larvae, food deprivation increases locomotor speed via octopamine-mediated structural plasticity of neuromuscular synapses, whereas tyramine reduces locomotor speed, but the underlying cellular and molecular mechanisms remain unknown. We show that tyramine is released into the CNS to reduce motoneuron intrinsic excitability and responses to excitatory cholinergic input, both by tyraminehonoka receptor activation and by downstrea…

Inhibitory Action of Glufosinate on Photosynthesis

1993

Glufosinate (phosphinothricin) irreversibly blocks the glutamine synthetase which subsequently gives rise to an accumulation of ammonium and to a strong decrease in some amino acids, especially glutamine and glutamate. Under atmospheric conditions (400 ppm CO2, 21% O2) glufosinate causes a rapid inhibition of photosynthesis, too. H ow ever, under non-photo respiratory conditions (1000 ppm CO2, 2% O2) only a slight inhibition of photosynthesis occurs with glufosinate. Since under both conditions an accumulation of ammonium occurs, it is concluded that inhibition of photosynthesis is not induced by the higher concentrations of ammonium. The results rather suggest that the absence of amino don…

Acetylcholine At Motor Nerves: Storage, Release, and Presynaptic Modulati On By Autoreceptors and Adrenoceptors

1992

Publisher Summary This chapter focuses on the modulation of acetylcholine release from the motor endplate by presynaptic receptors. An individual neuron can regulate its function, the release of transmitters or modulators, through the activation of local feedback loops. After escaping the neuronal membrane and entering the synaptic cleft (or extracellular space), the transmitter activates both the receptors localized at the endorgan (postsynaptic receptors) and the receptors localized at the nerve terminal within its diffusion radius (so-called presynaptic or neuronal receptors). Stimulation of presynaptic receptors triggers the generation of intracellular signals that modify ion channels o…

Discrete cortical representations and their stability in the presence of synaptic turnover

2015

Population imaging in mouse auditory cortex revealed clustering of neural responses to brief complex sounds: the activity of a local population typically falls close to one out of a small number of observed states [1]. These clusters appear to group sets of auditory stimuli into a discrete set of activity patterns and could thereby form the basis for representations of sound categories. However, to be useful for the brain, such representations should be robust against fluctuations in the underlying circuitry, which are significant even in the absences of any explicit learning paradigm [2]. Here we introduce a novel firing rate based circuit model of mouse auditory cortex to study the emerge…

2015

Primary neuronal cultures share many typical features with the in vivo situation, including similarities in distinct electrical activity patterns and synaptic network interactions. Here, we use multi-electrode array (MEA) recordings from spontaneously active cultures of wildtype and GAD67-GFP transgenic mice to evaluate which spike parameters differ between GABAergic interneurons and principal, putatively glutamatergic neurons. To analyze this question we combine MEA recordings with optical imaging in sparse cortical cultures to assign individual spikes to visually-identified single neurons. In our culture system, excitatory and inhibitory neurons are present at a similar ratio as described…

Chapter 21 Immunohistochemical evidence for a co-transmitter role of opioid peptides in primary sensory neurons

1988

Publisher Summary The purpose of this chapter is to answer several open questions regarding opioid peptides by using a highly sensitive light microscopic (LM) immunohistochemical approach. The chapter mentions the immunohistochemical evidence for a co-transmitter role of opioid peptides in primary sensory neurons. It introduces the concept that there is a functionally important tandem constellation of transmitters in a specific nociceptive population of primary sensory afferents consisting of (1) an inhibitory transmitter family, the opioid peptides, and (2) an excitatory transmitter family, the tachykinins. Small-diameter primary sensory neurons not only transmit nociceptive messages to ce…

Heterogeneous responses of nucleus incertus neurons to corticotrophin-releasing factor and coherent activity with hippocampal theta rhythm in the rat

2013

The nucleus incertus (NI) of the rat hindbrain is a putative node in the ascending control of the septohippocampal system and hippocampal theta rhythm and is stress and arousal responsive. NI contains GABA neurons that express multiple neuropeptides, including relaxin-3 (RLN3) and neuropeptide receptors, including corticotrophin-releasing factor receptor-1 (CRF-R1), but the precise anatomical and physiological characteristics of NI neurons are unclear. Therefore, we examined the firing properties of NI neurons and their responses to CRF, the correlation of these responses with occurrence of relaxin-3, and NI neuron morphology in the rat. Most NI neurons excited by intracerebroventricular CR…

Peripheral motor action of glucagon-like peptide-1 through enteric neuronal receptors

2010

Background  Glucagon-like peptide-1 (GLP-1) is a proglucagon-derived peptide expressed in the enteroendocrine-L cells of small and large intestine and released in response to meal ingestion. Glucagon-like peptide-1 exerts inhibitory effects on gastrointestinal motility through vagal afferents and central nervous mechanisms; however, no data is available about a direct influence on the gastrointestinal wall. Our aim was to investigate the effects of GLP-1 on the spontaneous and evoked mechanical activity of mouse duodenum and colon and to identify the presence and distribution of GLP-1 receptors (GLP-1R) in the muscle coat. Methods  Organ bath recording technique and immunohistochemistry wer…

GLP-2 receptor expression in excitatory and inhibitory enteric neurons and its role in mouse duodenum contractility

2011

Background  Glucagon-like peptide 2 (GLP-2), a nutrient-responsive hormone, exerts various actions in the gastrointestinal tract that are mediated by a G-protein coupled receptor called GLP-2R. A little information is available on GLP-2R expression in enteric neurons and nothing on the interstitial cells of Cajal (ICC). Methods  We investigated presence and distribution of the GLP-2R in the mouse duodenum by immunohistochemistry and the potential motor effects of GLP-2 on the spontaneous and neurally evoked mechanical activity. Key Results  The GLP-2R was expressed by the myenteric and submucosal neurons. Labelling was also present in nerve varicosities within the circular muscular layer an…

In vitro effects of estradiol, testosterone, and progesterone on 5-methoxyindole content, cyclic adenosine 3',5'-monophosphate synthesis, and norepin…

1986

To examine the effects of estradiol, testosterone, or progesterone on cyclic adenosine 3',5'-monophosphate (AMP) accumulation, 5-methoxyindole levels, and norepinephrine (NE) release by the female guinea pig pineal complex, samples of the deep, intermediate, or superficial portions of the complex were incubated in vitro with varied concentrations of either hormone. Exposure for 10 minutes to physiological amounts of estradiol (10 nM) or to 100 microM NE increased significantly cyclic AMP levels to the same extent in the three pineal regions. A maximal effect on cyclic AMP accumulation was observed at 100-nM concentrations of estradiol, with a tendency to return to basal levels at 1-10 micro…