GABA receptor mediation of median preoptic nucleus‐evoked inhibition of supraoptic neurosecretory neurones in rat.

Nissen, R.; Renaud, Leo P.

doi:10.1113/jphysiol.1994.sp020289

Cited by 63 publications

(34 citation statements)

References 35 publications

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“…MnPO relays the information from the OVLT to the magnocellular neurosecretory cells in the SON. Though a recent electrophysiological study (33 ) showed that GABAergic inhibitory neurones in the MnPO project to the SON, most SON neurones were excited by electrical stimulation of the MnPO in our previous study (15). And moreover, in the present study the MnPO neurones projecting to the SON area responded to haemodynamic or osmotic stimuli in the same manner as the SON neurones did ( 15); i.e.…”

Section: Discussionsupporting

confidence: 58%

Median Preoptic Neurones Projecting to the Supraoptic Nucleus are Sensitive to Haemodynamic Changes as well as to Rise in Plasma Osmolality in Rats

Aradachi

Honda

Negoro

et al. 1996

J Neuroendocrinology

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Extracellular single unit activity was recorded from 73 neurones in the median preoptic nucleus (MnPO), identified by antidromic activation as projecting to the supraoptic nucleus (SON) area in urethane-anaesthetized male rats. Thirteen of 73 identified MnPO neurones were silent, and 44 of 60 spontaneously active MnPO neurones were tested for their responses to electrical stimulation of the nucleus tractus solitarius (NTS). The cells were divided into 4 groups according to their responses; those which were excited orthodromically (OD+; n = 15), those which were unresponsive (UN; n = 21), those which were inhibited orthodromically (OD-; n = 4), those which showed initial inhibition followed by excitation (OD-+ n = 4). Some of these neurones were further tested for their responses to haemorrhage and/or produced by intraperitoneal injection of 1.5 M NaCl. Six out of 10 OD+ cells were excited by haemorrhage, 6 out of 11 OD+ cells were inhibited by phenylephrine, and 5 out of 9 OD+ cells were excited by hypertonic saline. On the other hand the UN cells tended to be unresponsive to each type of stimulus. Three out of 7 OD+ cells were excited by both haemorrhage and hypertonic saline, and 3 out of 8 OD+ cells were inhibited by phenylephrine and excited by hypertonic saline. The results may suggest that MnPO neurones which receive afferent input from the NTS may be sensitive not only to haemodynamic change but also to change in plasma osmotic pressure and that such population of MnPO neurones may integrate a part of the haemodynamic and osmotic information and contribute to the control of neurohypophysial hormone release.

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Section: Discussionsupporting

confidence: 58%

Median Preoptic Neurones Projecting to the Supraoptic Nucleus are Sensitive to Haemodynamic Changes as well as to Rise in Plasma Osmolality in Rats

Aradachi

Honda

Negoro

et al. 1996

J Neuroendocrinology

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“…In an earlier in vivo analysis, we reported that stimulation in MnPO evoked GABA A -mediated inhibition in target neurons in the supraoptic nucleus (27), implying that at least this output of MnPO was inhibitory in nature. Consistent with this notion are Fig.…”

Section: Perspectivesmentioning

confidence: 98%

Presynaptic α-adrenoceptors in median preoptic nucleus modulate inhibitory neurotransmission from subfornical organ and organum vasculosum lamina terminalis

Kolaj¹,

Renaud²

2007

American Journal of Physiology-Regulatory, Integrative and Comp

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The median preoptic nucleus (MnPO) in the lamina terminalis receives a prominent catecholaminergic innervation from the dorsomedial and ventrolateral medulla. The present investigation used whole cell patch-clamp recordings in rat brain slice preparations to evaluate the hypothesis that presynaptic adrenoceptors could modulate GABAergic inputs to MnPO neurons. Bath applications of norepinephrine (NE; 20-50 microM) induced a prolonged and reversible suppression of inhibitory postsynaptic currents (IPSCs) and reduced paired-pulse depression evoked by stimulation in the subfornical organ and organum vasculosum lamina terminalis. These events were not correlated with any observed changes in membrane conductance arising from NE activity at postsynaptic alpha(1)- or alpha(2)-adrenoceptors. Consistent with a role for presynaptic alpha(2)-adrenoceptors, responses were selectively mimicked by an alpha(2)-adrenoceptor agonist (UK-14304) and blockable with an alpha(2)-adrenoceptor antagonist (idazoxan). Although the alpha(1)-adrenoceptor agonist cirazoline and the alpha(1)-adrenoceptor antagonist prazosin were without effect on these evoked IPSCs, NE was noted to increase (via alpha(1)-adrenoceptors) or decrease (via alpha(2)-adrenoceptors) the frequency of spontaneous and tetrodotoxin-resistant miniature IPSCs. Collectively, these observations imply that both presynaptic and postsynaptic alpha(1)- and alpha(2)-adrenoceptors in MnPO are capable of selective modulation of rapid GABA(A) receptor-mediated inhibitory synaptic transmission along the lamina terminalis and therefore likely to exert a prominent influence in regulating cell excitability within the MnPO.

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“…Indeed, 20-30% of neurons in the MnPO are warm sensitive and have been proposed to play an important role in thermoregulation, including nonshivering thermogenesis (71). Efferent projections from the MnPO tend to be inhibitory (44), which is consistent with their GABAergic nature (43). Furthermore, MnPO neurons that project to the midbrain periaqueductal gray matter (which contains neurons generating excitatory signals for nonshivering thermogenesis) are activated by heat exposure (75), thus confirming their inhibitory role in the control of thermogenesis.…”

Section: Hyperthermia Induced By Ovlt Lesionmentioning

confidence: 99%

The organum vasculosum laminae terminalis in immune-to-brain febrigenic signaling: a reappraisal of lesion experiments

Romanovsky

Sugimoto²,

Simons³

et al. 2003

American Journal of Physiology-Regulatory, Integrative and Comp

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Romanovsky, Andrej A., Naotoshi Sugimoto, Christopher T. Simons, and William S. Hunter. The organum vasculosum laminae terminalis in immune-to-brain febrigenic signaling: a reappraisal of lesion experiments. Am J Physiol Regul Integr Comp Physiol 285: R420-R428, 2003. First published April 24, 2003 10.1152/ajpregu.00757. 2002The organum vasculosum laminae terminalis (OVLT) has been proposed to serve as the interface for blood-to-brain febrigenic signaling, because ablation of this structure affects the febrile response. However, lesioning the OVLT causes many "side effects" not fully accounted for in the fever literature. By placing OVLT-lesioned rats on intensive rehydration therapy, we attempted to prevent these side effects and to evaluate the febrile response in their absence. After the OVLT of Sprague-Dawley rats was lesioned electrolytically, the rats were given access to 5% sucrose for 1 wk to stimulate drinking. Sucrose consumption and body mass were monitored. The animals were examined twice a day for signs of dehydration and treated with isotonic saline (50 ml/kg sc) when indicated. This protocol eliminated mortality but not several acute and chronic side effects stemming from the lesion. The acute effects included adipsia and gross (14% of body weight) emaciation; chronic effects included hypernatremia, hyperosmolality, a suppressed drinking response to hypertonic saline, and previously unrecognized marked (by ϳ2°C) and long-lasting (Ͼ3 wk) hyperthermia. Because the hyperthermia was not accompanied by tail skin vasoconstriction, it likely reflected increased thermogenesis. After the rats recovered from the acute (but not chronic) side effects, their febrile response to IL-1␤ (500 ng/kg iv) was tested. The shamoperated rats developed typical monophasic fevers (ϳ0.5°C), the lesioned rats did not. However, the absence of the febrile response in the OVLT-lesioned rats likely resulted from the untreatable side effects. For example, hyperthermia at the time of pyrogen injection was high enough (39-40°C) to solely prevent fever from developing. Hence, the changed febrile responsiveness of OVLT-lesioned animals is given an alternative interpretation, unrelated to febrigenic signaling to the brain. fever; adipsia; third ventricle; median preoptic nucleus THERE IS LITTLE DOUBT that the febrile response is regulated by the central nervous system (CNS), but the mechanisms by which peripherally originating pyrogenic signals reach the brain remain unclear. At least four possibilities have been proposed. First, pyrogenic cytokines, such as IL-1␤, access the CNS by carriermediated transport across the blood-brain barrier (BBB) (2). Second, circulating pyrogens bind to the cerebral vascular endothelium and stimulate production of fever mediators, most importantly PGE 2 , by endothelial cells; endotheliocytes release PGE 2 into the brain tissue (10). Third, pyrogens act on neural terminals in peripheral tissues and convey febrigenic signals to the CNS via sensory fibers, e.g., those of the vagus nerve (7, 74). Fourt...

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GABA receptor mediation of median preoptic nucleus‐evoked inhibition of supraoptic neurosecretory neurones in rat.

Cited by 63 publications

References 35 publications

Median Preoptic Neurones Projecting to the Supraoptic Nucleus are Sensitive to Haemodynamic Changes as well as to Rise in Plasma Osmolality in Rats

Median Preoptic Neurones Projecting to the Supraoptic Nucleus are Sensitive to Haemodynamic Changes as well as to Rise in Plasma Osmolality in Rats

Presynaptic α-adrenoceptors in median preoptic nucleus modulate inhibitory neurotransmission from subfornical organ and organum vasculosum lamina terminalis

The organum vasculosum laminae terminalis in immune-to-brain febrigenic signaling: a reappraisal of lesion experiments

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