Angiotensin II receptor content within the subfornical organ and organum vasculosum lamina terminalis increases after experimental subarachnoid haemorrhage in rats

1996 ◽  
Vol 138 (4) ◽  
pp. 460-465 ◽  
Author(s):  
B. Açikgöz ◽  
T. Özgen ◽  
F. Özdoğan ◽  
A. Sungur ◽  
İ. Hakki Tekkök
Keyword(s):  
Angiotensin Ii ◽  
Subarachnoid Haemorrhage ◽  
Subfornical Organ ◽  
Lamina Terminalis ◽  
Angiotensin Ii Receptor ◽  
Experimental Subarachnoid Haemorrhage ◽  
Organum Vasculosum Lamina Terminalis ◽  
Organum Vasculosum

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

2007 ◽  
Vol 292 (5) ◽  
pp. R1907-R1915 ◽  
Author(s):  
Miloslav Kolaj ◽  
Leo P. Renaud
Keyword(s):  
Membrane Conductance ◽  
Subfornical Organ ◽  
Ventrolateral Medulla ◽  
Lamina Terminalis ◽  
Preoptic Nucleus ◽  
Median Preoptic Nucleus ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
Organum Vasculosum Lamina Terminalis ◽  
Organum Vasculosum

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 μM) 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 α1- or α2-adrenoceptors. Consistent with a role for presynaptic α2-adrenoceptors, responses were selectively mimicked by an α2-adrenoceptor agonist (UK-14304) and blockable with an α2-adrenoceptor antagonist (idazoxan). Although the α1-adrenoceptor agonist cirazoline and the α1-adrenoceptor antagonist prazosin were without effect on these evoked IPSCs, NE was noted to increase (via α1-adrenoceptors) or decrease (via α2-adrenoceptors) the frequency of spontaneous and tetrodotoxin-resistant miniature IPSCs. Collectively, these observations imply that both presynaptic and postsynaptic α1- and α2-adrenoceptors in MnPO are capable of selective modulation of rapid GABAA 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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