K. Magnusson et al., DIFFERENCE IN TESTOSTERONE SENSITIVITY IN MALE SPONTANEOUSLY HYPERTENSIVE (SHR) AND WISTAR-KYOTO RATS (WKY), Physiology & behavior, 60(3), 1996, pp. 907-912
The effects of castration and testosterone substitution on copulatory
behavior and arginine-vasopressin (AVP) concentrations in the lateral
septum (LS) were compared in the male spontaneously hypertensive rat (
SHR) and its normotensive counterpart, the Wistar-Kyoto rat (WKY). The
copulatory behavior was attenuated in the intact SHR and remained for
a shorter time after castration than in the WKY males. A higher dose
(1 mg/kg) of testosterone propionate (TP) was required in the castrate
d SHR to reestablish the copulatory behavior compared to the WKY (0.5
mg/kg). Following castration the main decline of AVP concentrations oc
curred over a period of 28 days. On postcastrational day 14, a time wh
en approximately 50% of the initial AVP concentration remained, the de
crease in the LS AVP content of the SHR surpassed that of the WKY. A d
ose-dependent increase of the AVP concentrations was achieved after 3
weeks of TP treatment (0.5 and 1.0 mg/kg, SC), which commenced 28 and
56 days after castration. The increase of AVP concentrations in the LS
after a submaximal dose of Tp (0.5 mg/kg)was less in the SHR than in
the WKY. It is concluded that the gonadal hormone control of the copul
atory behavior and AVP content in the terminal fields of the LS is cha
racterised by a lower sensitivity in the SHR compared to the WKY. The
data suggest that the low responsiveness to testosterone in the SHR co
mprises hypothalamic as well as extrahypothalamic neurons.