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EFFECTS OF NALOXONE ON LH SECRETION IN LONG-TERM OVARIECTOMIZED
RATS. T. FUNABASHI t A. KATO~AND F. KIMURA t Department of
Physiology, Yokohama Cit-yy University School of Medicine, 3-9
Fukuura t Kanazawa-ku, Yokohama 236, Japan.
The effects of naloxone (NAL), an opiate antagonist, on the
pulsatile secretion of LH were examined in female rats,
ovariectomized (OVX) for 4, 8, 16 or 32 weeks. Blood samples were
collected via an atrial cannula at 6-min intervals for a period of
180 min. During the first 90 min of bleeding, an equal volume of
saline was injected after withdrawal of each blood sample, while
during the second 90 min, the rats received either an intermittent
injection at each sampling time (4, 16 and 32-week OVX rats) or a
continuous infusion (8-week OVX rats) of NAL in saline at a dose of
0.5 or 1.0 mg/kg/h. Serum concentrations of LH were determined with
RIA, and LH pulsatility was statistically compared between the
first and second 90-min periods. In 4-week OVX rats, intermittent
injections of NAL decreased pulse frequency without changes in
pulse amplitude and increased overall mean LH levels. In 16- and
32-week OVX rats, intermittent injections of NAL also decreased
pulse frequency and pulse amplitude, although mean LH levels were
not increased. The effects caused by continuous infusion were
similar to those by intermittent injections, but were rather
attenuated. The results suggest that endogenous opioid peptides
play a significant role in the mechanism controlling pulses of
LH-releasing hormone in the absence of gonadal steroid
hormones.
DISTRIBUTION OF ESTROGEN RECEPTOR IN THE BRAIN OF NORMAL,
OVARIECTOMIZED, AND CASTRATED
RAT. KAZUNARI YURI, MITSUHIRO KAWATA AND YUTAKA SANO,
Dep_grtment 0_f A n a t o ~ _ ~ o t O _P_re_f_e_c_turai
U n i v e r s i t y of Medicine,
Kaw_ara_machirH_irok_gj_i,_Iam_i~ku, Kyoto 602, J a p a n . E s t r
o g e n r e c e p t o r (ER) was d e t e c t e d i m m u n o h i s
t o c h e m i c a l l y u s i n g a n t i - E R monoc lona i a n t
i b o d y ra i sed
b y human b r e a s t c a n c e r ce i l s MCF-7. Eight Wistar r
a t s (body w e i g h t 200-250g) w e r e d iv ided into 4 groups:
(a) normal femaie r a t s , (b) o v a r i e c t o m i z e d r a t s
, (c) n o r m a l male r a t s , (d) c a s t r a t e d rats . Under
p e n t o b a r b i t a i a n e s t h e s i a , r a t s w e r e p e
r f u s e d w i t h f i x a t i v e c o n t a i n i n g 4~ p a r a
f o r m a i d e h y d e a n d 0.2~
p i o r i c ac id . The b r a i n was e x t r a c t e d a n d 20
~ m - t h i c k f r o z e n s e c t i o n s w e r e made. PAP r e a
c t i o n w a s
p e r f o r m e d b y ABBOTT ER-ICA monoc lona i (Da inabo t ) w
i t h a f r e e - f l o a t i n g method. E R - i m m u n o r e a c
t i v i t y was d i f f u s e l y d e t e c t e d in the n e u r o
n s of the fo l lowing areas: l a t e r a l s e p t a l n u c l e u
s , preopt ic a r e a ( p e r i v e n t r i c u i a r a n d med ia
l n u c l e i ) , b e d n u c l e u s of s t r ia terminai i s , a
n t e r i o r and p e r i v e n t r i c u l a r h y p o t h a i a m
i c nucle i , v e n t r o m e d i a l hypotha iamic n u c l e u s ,
s ep tohypotha iamic n u c l e u s , amygdaio id n u c l e u s and
c e n t r a l g r e y of t h e m i d b r a i n . The immunoreac t
iv i ty of o v a r e c t o m i z e d r a t was s t r o n g e r t h
a n t h a t of n o r m a l r a t a n d t h e n u m b e r of p o s i
t i v e n e u r o n s i n c r e a s e d , w h e r e a s i m m u n o
r e a c t i v i t y of c a s t r a t e d r a t w a s w e a k e r t
h a n t h a t of n o r m a l r a t a n d t h e n u m b e r of p o s
i t i v e n e u r o n s decreased .
HISTOCHEMICAL STUDIES ON "NEUROSTEROIDS" HISAO YAMADA 1 and
YUTAKA SAN02~ Dept. of Anatomy. iShi~a University of Medical
Science, (ZKyoto Pref. Univ. of Med.), 0tsu 520-21, JAPAN The
production and metabolism of bioactive steroids in neurons (but not
glial
cells) have hardly been investigated. "NEUROSTEROID" is thought
to be a new research field of the neurosciences. In the present
report, we review our serial studies on (i) newly discovered
endogenous factor, EDLS, which is thought to be a steroid: (2) sex
steroid receptor; (3) P450 enzyme AROMATASE which converts
androgens into estrogens. (i) Endogenous digitalls-like
substance (EDLS) causes vasoconstriction and
natriuresis. This chemical structure has not been determined
yet, but it is well known that EDLS inhibits Na.K-ATPase and has
cross-immunoreactivity to digoxin- specific antibody. An
immunohistcchemical technique using digoxin-antibody was utlllsed
in our study. EDLS neurons were distributed in the hypothalamlc
magnocellular nuclei (SON & PVN). (2) The immunoreactivltles
for antibody to estrogen receptor (ER) were observed in the cell
nucleus of neurons which were located in the preoptic area, BST,
anterior hypothalamus, hypothalamic ventromedlal nucleus,
amygdalold nuclei, and mesencephalic central gray. (3)
Aromatase-containing neurons were distributed in the ventral
pallldum, preoptic area. anterior hypothalamus, amygdalold nuclei,
etc.
