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Androgens prevent changes in electrophysiological properties of rat septo-hippocampal neurons by daily repeated cold exposures
P1-57 AGE-RELATED CHANGE S. Era, K. Kuwata, Dept. of Physiol., for Compreh. Med.
IN REDOX STATE OF HUMAN SERUM A L B U M I N H. Imai, K. Nakamura, T. Hayashi, M. Sogami* Gifu Univ. Sch. of Med., Gifu, *Div. of Mol. Sci., F u j i t a Health Univ., Toyoake, J a p a n
Physiol.,
Inst.
H u m a n serum a l b u m i n (HSA) is the m i x t u r e of human m e r c a p t a l b u m i n (HMA, r e d u c e d form) and human n o n m e r c a p t a l b u m i n (HNA, o x i d i z e d form). We d e v e l o p e d a rapid and c o n c i s e h i g h - p e r f o r m a n c e liquid c h r o m a t o g r a p h i c (HPLC) system to o b t a i n the clear r e s o l u t i o n of HSA into HMA and HNA at neutral pH, using an A s a h i p a k GS520H column and found that the f r a c t i o n of HMA (f(HMA)) is m a r k e d l y d e c r e a s e d in various d i s e a s e s and some p h y s i c a l conditions, c o m p a r e d with that in he'althy young male subjects. So, we s y s t e m a t i c a l l y a n a l y z e d the HMA fraction of HSA a s s o c i a t e d with age. Sera from healthy young male subjects (18-24 years old) were o b t a i n e d at Gifu U n i v e r s i t y and sera of h e a l t h y elderly subjects (60-90 years old) were s u p p l i e d by T o k y o M e t r o p o l i t a n G e r i a t r i c Hospital. The mean value of the HMA f r a c t i o n (f(HMA)) for healthy young male subjects was 0.76 + 0.04 (20.1 ÷ 1.70 years old, n = 54). However, the f(HMA, 60-90) value for h e a l t h y elderly subjects (where the numbers in b r a c k e t s ihdicate the range of ages) was 0.48 + 0.06 (74.5 ÷ 9.96 years old, n = 183). In healthy e l d e r l y subjects, f(HMA) was s i g n i f i c a n t l y lower ~han in healthy y o u n g . m a l e subjects, i n d i c a t i n g that HSA in the elderly becomes more o x i d i z e d . t h a n in the young subjects. Kuck et al. (Exp. Eye Res. 1982, 34:23) r e p o r t e d that s u l f h y d r y l c o n t e n t of human lenses falls with aging and Ferrer et al. (Biochem. J. 1990, 269:531) r e p o r t e d that g l u t a t h i o n e synthesis does not occur in lenses from old animals. Low f(HMA) of HSA in the e l d e r l y might be Ln good a g r e e m e n t with " findings by Kuck et al. and Ferrer et al. C o n s e q u e n t l y , we suggest that one of the i m p o r t a n t functions of serum a l b u m i n could be to p a r t i c i p a t e in the m a i n t e n a n c e of a c o n s t a n t redox p o t e n t i a l in the e x t r a c e l l u l a r fluids, thus s e c u r i n g a certain redox buffer capacity. f(HMA) on HSA might reflect this buffer c a p a c i t ~ with age.
P1-58 ANDROGENS PREVENT CHANGES IN ELECTROPHYSIOLOGICALPROPERTIES OF RAT SEPTO-HIPPOCAMPAL NEURONS BY DAILY REPEATED COLD EXPOSURES A. Ushigome 1, J. Yano 1, M. Matsuda 1, M. Nomura 2 and J. Tanaka 1 1) Dept. of Human Development, Naruto Univ. of Education, Tokushima, Japan
2) Dept. of Physiol.,
Saltarna Med. Saitama, Japan Gonadal steroid hormones can produce substantial morphological changes in neural circuits. In a n a t t e m p t to clarify w h e t h e r or not a n d r o g e n s cause changes in septo-hippocampal n e u r o n s , the electrophysiological properties of septum n e u r o n s that were antidromically activated by electrical stimulation of the fimbria were investigated in intact, castrated, and testosterone-treated male rats (3-5 months old) u n d e r urethane anesthesia. No significant group differences in the latency and threshold of antidromic activation, c o n d u c t i o n velocity, firing rate, absolute refractory period, or successful antidromic propagation ratio were observed. In the rats which received daily repeated cold exposures (5 weeks) at a fixed time once a day, we also examined the effects of androgens on the properties of s e p t o - h i p p o c a m p a l n e u r o n s . No significant group differences in the latency a n d t h r e s h o l d of antidromic activation or conduction velocity were found. The spontaneous firing rate was significantly higher a n d the absolute refractory period was significantly shorter in intact and testosterone-treated castrated males t h a n in u n t r e a t e d castrates.
In addition, the degree of successful a n t i d r o m i c
propagation into the somatodendritic complex was markedly lower in castrated males than in the other two groups.
In both the intact and testosterone-treated castrated males, there was no s i g n i f i c a n t
difference in any of these properties between cold-exposed and unexposed groups. These results imply that androgen may act to prevent alterations in the septo-hippocampal system by cold stress.
447
IN REDOX STATE OF HUMAN SERUM A L B U M I N H. Imai, K. Nakamura, T. Hayashi, M. Sogami* Gifu Univ. Sch. of Med., Gifu, *Div. of Mol. Sci., F u j i t a Health Univ., Toyoake, J a p a n
Physiol.,
Inst.
H u m a n serum a l b u m i n (HSA) is the m i x t u r e of human m e r c a p t a l b u m i n (HMA, r e d u c e d form) and human n o n m e r c a p t a l b u m i n (HNA, o x i d i z e d form). We d e v e l o p e d a rapid and c o n c i s e h i g h - p e r f o r m a n c e liquid c h r o m a t o g r a p h i c (HPLC) system to o b t a i n the clear r e s o l u t i o n of HSA into HMA and HNA at neutral pH, using an A s a h i p a k GS520H column and found that the f r a c t i o n of HMA (f(HMA)) is m a r k e d l y d e c r e a s e d in various d i s e a s e s and some p h y s i c a l conditions, c o m p a r e d with that in he'althy young male subjects. So, we s y s t e m a t i c a l l y a n a l y z e d the HMA fraction of HSA a s s o c i a t e d with age. Sera from healthy young male subjects (18-24 years old) were o b t a i n e d at Gifu U n i v e r s i t y and sera of h e a l t h y elderly subjects (60-90 years old) were s u p p l i e d by T o k y o M e t r o p o l i t a n G e r i a t r i c Hospital. The mean value of the HMA f r a c t i o n (f(HMA)) for healthy young male subjects was 0.76 + 0.04 (20.1 ÷ 1.70 years old, n = 54). However, the f(HMA, 60-90) value for h e a l t h y elderly subjects (where the numbers in b r a c k e t s ihdicate the range of ages) was 0.48 + 0.06 (74.5 ÷ 9.96 years old, n = 183). In healthy e l d e r l y subjects, f(HMA) was s i g n i f i c a n t l y lower ~han in healthy y o u n g . m a l e subjects, i n d i c a t i n g that HSA in the elderly becomes more o x i d i z e d . t h a n in the young subjects. Kuck et al. (Exp. Eye Res. 1982, 34:23) r e p o r t e d that s u l f h y d r y l c o n t e n t of human lenses falls with aging and Ferrer et al. (Biochem. J. 1990, 269:531) r e p o r t e d that g l u t a t h i o n e synthesis does not occur in lenses from old animals. Low f(HMA) of HSA in the e l d e r l y might be Ln good a g r e e m e n t with " findings by Kuck et al. and Ferrer et al. C o n s e q u e n t l y , we suggest that one of the i m p o r t a n t functions of serum a l b u m i n could be to p a r t i c i p a t e in the m a i n t e n a n c e of a c o n s t a n t redox p o t e n t i a l in the e x t r a c e l l u l a r fluids, thus s e c u r i n g a certain redox buffer capacity. f(HMA) on HSA might reflect this buffer c a p a c i t ~ with age.
P1-58 ANDROGENS PREVENT CHANGES IN ELECTROPHYSIOLOGICALPROPERTIES OF RAT SEPTO-HIPPOCAMPAL NEURONS BY DAILY REPEATED COLD EXPOSURES A. Ushigome 1, J. Yano 1, M. Matsuda 1, M. Nomura 2 and J. Tanaka 1 1) Dept. of Human Development, Naruto Univ. of Education, Tokushima, Japan
2) Dept. of Physiol.,
Saltarna Med. Saitama, Japan Gonadal steroid hormones can produce substantial morphological changes in neural circuits. In a n a t t e m p t to clarify w h e t h e r or not a n d r o g e n s cause changes in septo-hippocampal n e u r o n s , the electrophysiological properties of septum n e u r o n s that were antidromically activated by electrical stimulation of the fimbria were investigated in intact, castrated, and testosterone-treated male rats (3-5 months old) u n d e r urethane anesthesia. No significant group differences in the latency and threshold of antidromic activation, c o n d u c t i o n velocity, firing rate, absolute refractory period, or successful antidromic propagation ratio were observed. In the rats which received daily repeated cold exposures (5 weeks) at a fixed time once a day, we also examined the effects of androgens on the properties of s e p t o - h i p p o c a m p a l n e u r o n s . No significant group differences in the latency a n d t h r e s h o l d of antidromic activation or conduction velocity were found. The spontaneous firing rate was significantly higher a n d the absolute refractory period was significantly shorter in intact and testosterone-treated castrated males t h a n in u n t r e a t e d castrates.
In addition, the degree of successful a n t i d r o m i c
propagation into the somatodendritic complex was markedly lower in castrated males than in the other two groups.
In both the intact and testosterone-treated castrated males, there was no s i g n i f i c a n t
difference in any of these properties between cold-exposed and unexposed groups. These results imply that androgen may act to prevent alterations in the septo-hippocampal system by cold stress.
447