Kk. Chen et Ls. Chang, Oxytocinergic neurotransmission at the hippocampus in the central neural regulation of penile erection in the rat, UROLOGY, 58(1), 2001, pp. 107-112
Objectives. To investigate whether there is an oxytocinergic neurotransmiss
ion at the hippocampus involved in the central regulation of penile erectio
n in the rat.
Methods. Male adult Sprague-Dawley (n = 27) rats anesthetized with pentobar
bital were used. A 26-gauge needle was inserted into the corpus cavernosum
to measure the intracavernous pressure (ICP) and the systemic and mean arte
rial pressure and heart rate simultaneously. The following studies were per
formed: stereotaxic delivery of oxytocin acetate (3 pmol/100 nL) into the h
ippocampus; microinjection of a mixture of [d(CH2)(5)-Tyr(Me)(2)-Orn(8)]-va
sotocin (3 pmol/100 nL) and oxytocin (3 pmo1/100 nL) into the hippocampus;
injection of saline into the hippocampus; and intracavernous injection of o
xytocin (3 pmol/100 muL). The ICP and hemodynamic parameters were monitored
after each administration of the experimental agents.
Results. After administration of oxytocin into the hippocampus, a significa
nt increase in the ICP occurred from resting (8.8 +/-1.7 mm Hg) to a peak a
t 49.6 +/- 12.5 mm Hg and persisted for 18.6 +/-9.4 minutes after an onset
latency of 500.0 +/- 389.7 seconds. However, no change in the ICP occurred
after administration of [d(CH2)(5)-Tyr(Me)(2)-Orn(8)]-vasotocin plus oxytoc
in into the hippocampus. In addition, no elevation of ICP occurred after ad
ministration of saline to the hippocampus or after intracavernous injection
of oxytocin.
Conclusions. The results demonstrate that administration of oxytocin into t
he hippocampus induces penile erection in the rat. However, concomitant adm
inistration of oxytocin and its antagonist was ineffective in eliciting pen
ile erection. These observations suggest that oxytocinergic neurotransmissi
on at the hippocampus may be involved in the central neural regulation of t
he penile erection in the rat. UROLOGY 58: 107-112, 2001. (C) 2001, Elsevie
r Science Inc.