# Endo_07.ode # # Computer code used in the article "Oxytocin Action at the # Lactotroph is Required for Prolactin Surges in Cervically Stimulated # Ovariectomized Rats" by D. T. McKee, M. O. Poletini, R. Bertram, and # M. E. Freeman, Endocrinology, 148:4649--4657, 2007. It can be used # with the software package XPPAUT, which can be downloaded (for free) # from the web page of Bard Ermentrout. # Variables (dimensionless): p = prolactin concentration # d = dopamine concentration # ocs = oxytocin concentration resulting from CS # opvn = oxytocin concentration from PVN # op = oxytocin concentration in pituitary # vip = VIP neuron activity # N = interneuron activity p(0)=0 d(0)=20 ocs(0)=0 opvn(0)=0 N(0)=0 # units of t are hr # prolactin parameters par vop=1.0,Tp=1, q=0.5, kd=1 # dopamine parameters par Td=10, kp=0.3, rv=2, tau=3 # OT-sensing neuron parameters par vcs=0.0002, rn=0.2 # Cervical stimulation (causing OT pulse) par tcs=48, p_cs=1000, tpdur=2 I = p_cs*(heav(t-tcs)-heav(t-tcs-tpdur)) # Circadian VIP neuron activity par period=24, tf1=2, vipdur=3 vip = heav(mod(t,period)-tf1)-heav(mod(t,period)-(tf1+vipdur)) # OT from OT neurons of the PVN to the pituitary par O_pit=3, ko=1 To = O_pit*heav(t-tcs) # Total OT in pituitary op = Opvn + ocs # OT antagonist (OTA) application par tOTA=24, tOTAdur=96 OTA = (heav(t-tOTA)-heav(t-tOTA-tOTAdur)) vo = vop*(1-OTA) # Equations p' = (Tp+vo*op)*(1/(kd+d^2))-q*p d' = Td*(1-N)+kp*delay(p,tau)^2-q*d-rv*vip*d ocs' = I-q*ocs opvn' = To/(1+ko*p^2)-q*opvn N' = vcs*ocs-rn*N*(N-.5)*(N-1) aux tdays=t/24 aux Vip=vip aux Op=op aux OTA=OTA # set max delay and other xpp parameters @ delay=6, dt=0.2, total=425, maxstor=20000 @ bounds=10000000, xp=tdays, yp=p, bell=off @ xlo=0, xhi=16, ylo=0, yhi=10 done