PHARMACOLOGICAL ANALYSIS OF THE NORADRENERGIC CONTROL OF CENTRAL SYMPATHETIC AND SOMATIC REFLEXES CONTROLLING THE LOWER URINARY-TRACT IN THE ANESTHETIZED CAT
H. Danuser et al., PHARMACOLOGICAL ANALYSIS OF THE NORADRENERGIC CONTROL OF CENTRAL SYMPATHETIC AND SOMATIC REFLEXES CONTROLLING THE LOWER URINARY-TRACT IN THE ANESTHETIZED CAT, The Journal of pharmacology and experimental therapeutics, 274(2), 1995, pp. 820-825
Norepinephrine (NE)-containing terminals densely innervate sympathetic
preganglionic neurons in the intermediolateral nucleus and somatic mo
tor neurons in Onuf's nucleus that project through the hypogastric and
pudendal nerves, respectively, to innervate the lower urinary tract.
in the present study, we pharmacologically analyzed the role of noradr
energic systems on the sympathetic and somatic pathways to the lower u
rinary tract and asked: 1) Are alpha-1, alpha-2, or beta-adrenergic re
ceptors tonically active along sympathetic and/or somatic reflex pathw
ays? And 2) what is the net effect of increasing the extracellular lev
els of NE by administration of a NE reuptake inhibitor? To address the
se questions, we recorded evoked potentials from the central ends of t
he hypogastric and pudendal nerves in response to electrical stimulati
on of the pelvic and pudendal nerves in chloralose-anesthetized cats,
and the effects of prazosin (1-300 mu g/kg i.v.), an alpha-1-adrenergi
c receptor antagonist; idazoxan (1-300 mu g/kg i.v), an alpha-2-adrene
rgic receptor antagonist; propranolol (1 mg/kg i.v.), a beta-adrenergi
c receptor antagonist; and tomoxetine (0.003-3 mg/kg i.v.), a selectiv
e NE reuptake inhibitor, were examined. The results indicate that faci
litatory alpha-1-adrenergic receptors are tonically active along both
sympathetic and somatic reflex pathways, whereas inhibitory alpha-2-ad
renergic receptors are not tonically active. The net effect of acute i
nhibition of NE reuptake along sympathetic reflex pathways is increase
d activation of inhibitory alpha-2-adrenergic receptors. Along somatic
reflex pathways, increased activation of both facilitatory alpha-1- a
nd inhibitory alpha-2-adrenergic receptors were recorded after acute N
E reuptake inhibition. No role for central beta-adrenergic receptors w
as noted.