Vasopressin Produces Inhibition on Phrenic Nerve Activity and Apnea through V(subscript 1A) Receptors in the Area Postrema in Rats

Shu-Ju Yang ； Kun-Ze Lee ； Chung-Hsin Wu ； Kwok-Tung Lu ； Ji-Chuu Hwang

《The Chinese Journal of Physiology》 49卷6期 (2006/12) Pp. 313-325

並列摘要

The area postrema (AP) is the most caudal circumventricular organ in the central nervous system and contains arginine vasopressin (AVP) receptors. To investigate that AVP receptors in the AP might participate in the modulation of respiration, the adult rat was anesthetized with urethane (1.2 g/kg, i.p.), paralyzed, ventilated artificially, and maintained at normocapnia in hyperoxia. The phrenic nerve was separated at C4 level. Phrenic burst was amplified, filtered, integrated, and then stored in the hard disc via the PowerLab system. Three doses of AVP and an AVP V(subscript 1A) receptor antagonist, [β-mercapto-β, β-cyclopentamethylenepropionyl^1,-O-Me-Tyr^2,Arg^8]-vasopressin, were microinjected into the AP through a pair of microelectrodes. The moderate and high doses of AVP reduced the PNA to 72% and 45% of the control (P＜0.05), extended the mean TE from 1.4 s before AVP to 4.0 s and 7.6 s, (P＜0.05), and decrease in BP by 26 and 37 mmHg (P＜0.05), respectively. These significant reductions in PNA and BP and elongation of TE were totally abolished by the pre-treatment of the AVP V(subscript 1A) receptor antagonist and by application of lidocaine or CoCl2 at the nucleus tractus solitarius (NTS). Moreover, pulmonary inhibition caused by AVP was significantly attenuated by hypercapnia. These results strongly suggest that AVP V(subscript 1A) receptors in the AP may participate in the modulation of cardiopulmonary functions through the activation of V(subscript 1A) receptors and the pathway connected to the NTS. They may also indicate that a putative vasopressinergic pathway has a projection to the AP to alter the excitability of neurons having AVP V(subscript 1A) receptors and results in an inhibition of cardiopulmonary functions via the connection between the AP and NTS.

並列關鍵字

area postrema ； arginine vasopressin ； V(subscript 1A) receptor ； phrenic nerve ； the nucleus of the ； tractus solitarius ； rat

參考文獻

Bhatnager, T.,Chtrvanshi, V.C.,Sapru, H.N.(1999).Cardiovascular responses to microinjections of excitatory amino acids into the area postrema of the rat.Brain Res..822,129-199.

Bianchi, A.L.,Denavit-Saubie, M.,Champagnat, J.(1995).Central control of breathing in mammals: neuronal circuitry, membrane properties, and neurotransmitters.Physiol. Rev..75,1-45.

Blessing, W.W.,Hedger, S.C.,Joh, T.H.,Willoghby, J.O.(1987).Neurons in the area postrema are the only catecholamine-synthesizing cells in the medulla or pons with projections to the rostral ventrolateral medulla (C1-area) in the rabbit.Brain Res..419,336-340.

Bongianni, F.,Mutolo, D.,Srinivasan, M.,Staderini, G.,Baccari, M.C.,Calamai, F.,Pantaleo, T.(1994).Gastric relaxation in response to chemical stimulation of the area postrema in the rabbit.Brain Res..646,307-311.

Bongianni, F.,Mutolo, D.,Carfi, M.,Pantaleo, T.(1998).Area postrema glutamate receptors mediate respiratory and gastric responses in the rabbit.Neuro Report.9,2051-2062.