Electrophysiological actions of norepinephrine in rat lateral hypothalamus. II. An in vitro study of the effects of iontophoretically applied norepinephrine on LH neuronal responses to γ-aminobutyric acid (GABA)

Jung-Tung, Cheng; Sessler, Francis M.; Azizi, S. Ausim; Chapin, John K.; Waterhouse, Barry D.

doi:10.1016/0006-8993(88)91299-1

Cited by 17 publications

(2 citation statements)

References 23 publications

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“…The interaction was termed "antagonistic" when the excitatory response was more suppressed than spontaneous firing during VIP iontophoresis. These criteria for quantitative evaluation of VIP interactions with neuronal responses to synaptic stimuli have been employed previously to asses NE actions in cerebral cortex (30), cerebellum (19,28) and hypothalamus (4,27).…”

Section: Methodsmentioning

confidence: 99%

Electrophysiological actions of VIP in rat somatosensory cortex

et al. 1991

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Electrophysiological and biochemical studies suggest that VIP may exert a facilitating action in the neocortical local circuitry. In the present study, we examined the actions of VIP and VIP + norepinephrine (NE) on somatosensory cortical neuron responses to direct application of the putative transmitters acetylcholine (ACh) and gamma-aminobutyric acid (GABA). Spontaneous and transmitter-induced discharges of cortical neurons from halothane-anesthetized rats were monitored before, during and after VIP, NE and VIP + NE iontophoresis. In 57 VIP-sensitive cells tested, VIP application (5-70 nA) increased (n = 18), decreased (n = 36) or had biphasic actions (n = 3) on background firing rate. In a group of 20 neurons tested for NE + VIP, the combined effect of both peptide and bioamine was predominantly (70%) inhibitory. On the other hand, inhibitory and excitatory responses of cortical neurons to GABA (11 of 15 cases) and ACh (10 of 18 cases), respectively, were enhanced during VIP iontophoresis. Concomitant application of VIP and NE produced additive (n = 2) or more than additive (n = 3) enhancing effects on GABA inhibition. NE administration reversed or enhanced further VIP modulatory actions on ACh-induced excitation. These findings provide electrophysiological evidence that NE and VIP afferents may exert convergent influences on cortical neuronal responses to afferent synaptic inputs such that modulatory actions are anatomically focused within the cortex.

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Section: Methodsmentioning

confidence: 99%

Electrophysiological actions of VIP in rat somatosensory cortex

et al. 1991

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“…The activity of individual neurons in these areas is modulated in vitro (Cheng et al, 1988) by several neurotransmitters that affect eating, suggesting that individual cells may integrate the effects of a variety of feeding-related neurochemicals. Recent evidence suggests that the cAMP-synthesizing enzyme adenylyl cyclase (AC) may function as a coincidence detector for activation of a variety of metabotropic receptors (Lustig et al, 1993), and we have shown that PFH and LH microinjection of the cAMP analog 8-bromocAMP (8-br-cAMP) or drugs that increase levels of endogenous cAMP elicits a robust eating response in satiated animals (Gillard et al, 1997a).…”

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confidence: 99%

The Second Messenger cAMP Elicits Eating by an Anatomically Specific Action in the Perifornical Hypothalamus

Gillard¹,

Khan

Grewal³

et al. 1998

J. Neurosci.

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We have previously shown that a membrane-permeant analog of cAMP, 8-bromo-cAMP (8-br-cAMP), elicits a vigorous eating response when microinjected into the perifornical hypothalamus (PFH) or lateral hypothalamus (LH) of satiated rats, suggesting that increases in cAMP in these areas may be important in the neural control of eating. To determine the locus of this effect, we compared the ability of 8-br-cAMP (1-100 nmol/0.3 l) to elicit eating after microinjection into the PFH, LH, or the following bracketing areas: the anterior and posterior LH, paraventricular nucleus of the hypothalamus, thalamus, and amygdala. 8-br-cAMP at 50 nmol elicited eating (Ն3.4 gm in 2 hr) exclusively in the PFH and LH. At 100 nmol, 8-br-cAMP elicited a larger response in these areas and elicited a smaller, more variable response in the thalamus. We similarly mapped the feeding-stimulatory effects of compounds that increase endogenous cellular cAMP in naive rats. Combined microinjection of matched doses (300 nmol) of 3-isobutyl-1-methylxanthine and 7-deacetyl-7-O-(N-methylpiperazino)-␥-butyryl-forskolin was effective exclusively in the PFH, eliciting an average 2 hr food intake of 8.4 Ϯ 2.0 gm. Collectively, these results suggest that increases in cellular cAMP within a specific brain site, the PFH, may play a role in the neural stimulation of eating.

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