Inhibitory coupling

Wang J, Ciofi P, Crowley WR (1996) Neuropeptide Y suppresses prolactin secretion from rat anterior pituitary cells evidence for interactions with dopamine through inhibitory coupling to calcium entry. Endocrinology 737 587-594. 

The compehtion in the MB lobes is in this more detailed, time-resolved model implemented by a straightforward all-to-all inhibitory coupling between the eKCs. Whichever eKCs fire first will inhibit other eKCs and prevent them from firing at the same time. It turns out that this simple lateral interaction between eKCs is enough to implement the winner-take-all situation we previously imposed by hand and to shape the output code. 

Since T < 0, an oscillatory instability of the unifor m steady state of Q occurs only for networks with inhibitory coupling, i.e., and F have opposite signs. Interestingly, for kinetic schemes that like the Oregonator model and activator-inhibitor schemes in general have J22 < 0, a stationary instability also occurs only for networks with inhibitory coupling. If r > A//22 > the stationary instability is the primary instability otherwise, the oscillatory instability occurs first. 

Equation (13.163) implies that an increase in the light intensity leads to a decrease in the production rate of the activator. Therefore = 1 corresponds again to inhibitory coupling and c = — 1 to activatory coupling. 

The uniform steady state undergoes a stationary instability for inhibitory coupling at... 

Fig. 13.17 Stationary pattern for the four graphs from Fig. 13.16 with inhibitory coupling and Lengyel-Epstein kinetics. The stationary value of the activator concentration is plotted vs the reactor number. (The inhibitor concentration shows quahtatively the same pattern.) Parameter values a = 10.0, Q = 0.1, a = 1.0, b = 5.0, and k = 23.56824264/ j8jo. Reprinted from [209]. Copyright 2006, with permission from Elsevier...

Apelin receptors activate several signalling pathways including coupling through inhibitory G-proteins (G ) and Ras-independent activation of extracellular-regulated kinases (ERKs) via protein kinase C (PKC). The apelin receptor is one of number of G-protein-coupled receptors that can act as an alternative coreceptor for entry into cells of HIV and simian immunodeficiency vims (SIV) strains in human U87 cells expressing CD4 in vitro. Apelin peptides blocks entry of HIV but display different potencies, with apelin-36 being more effective than shorter sequences [3]. 

GABAb receptors mediate the slow and prolonged physiological effects of the inhibitory neurotransmitter GABA. Functional GABAb receptors are comprised of two subunits, GABAbR1 and GABAbR2. Both subunits are G-protein-coupled receptors, which couple to the Gi/o family and are densely expressed at spinal nociceptive synapses. 

Somatostatin acts on various organs, tissues and cells as neurotransmitter, paracrine/autocrine and endocrine regulator on cell secretion, smooth muscle contractility, nutrient absorption, cell growth and neurotransmission [1]. Some of its mainly inhibitory effects are listed in Table 1. Somatostatin mediates its function via a family of heptahelical G-protein-coupled receptors termed... 

Synaptic vesicles isolated from brain exhibit four distinct vesicular neurotransmitter transport activities one for monoamines, a second for acetylcholine, a third for the inhibitory neurotransmitters GABA and glycine, and a fourth for glutamate [1], Unlike Na+-dependent plasma membrane transporters, the vesicular activities couple to a proton electrochemical gradient (A. lh+) across the vesicle membrane generated by the vacuolar H+-ATPase ( vacuolar type proton translocating ATPase). Although all of the vesicular transport systems rely on ApH+, the relative dependence on the chemical and electrical components varies (Fig. 1). The... 

The mu, delta and kappa opioid receptors are coupled to G° and G proteins and the inhibitory actions of the opioids occur from the closing of calcium channels (in the case of the K receptor) and the opening of potassium channels (for /i, d and ORL-1). These actions result in either reductions in transmitter release or depression of neuronal excitability depending on the pre- or postsynaptic location of the receptors. Excitatory effects can also occur via indirect mechanisms such as disinhibition, which have been reported in the substantia gelatinosa and the hippocampus. Flere, the activation of opioid receptors on GABA neurons results in removal of GABA-mediated inhibition and so leads to facilitation. 

Somatostatin exists in two forms, a 14 and a 28 amino-acid form called SRIF-14 and SRIF-28, respectively. Both are widely distributed in the CNS and the peptide produces inhibitory effects on neurons via G-protein-coupled opening of potassium channels. The original receptor division was twofold with a SRIF-1 and -2 receptor division but it is now clear that what are now known as sst2, 3 and 4 subtypes make up the former receptor while the sstl and 4 receptors are the original SRIF-2 site. 

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