1134
Speeialia
i n d i v i d u a l , i.e., 2 h a f t e r t h e m e a l ; in t h e l a t e r s a m p l e s t h e i n t e n s i t y of t h a t b a n d t h e n decreases p r o g r e s s i v e l y w i t h t i m e following e a t i n g s u c h t h a t i t h a s or h a s n e a r l y r e t u r n e d t o b a s e line level in s a m p l e No. 5. 2. T h e r e are differences in t h e a p o p r o t e i n b a n d s in t h e region b e t w e e n p H 6.5 a n d 7.5 b e t w e e n t h e pre- a n d p o s t e a t i n g samples. More i n t e n s e l y s t a i n i n g b a n d s occur in s a m p l e s 2 a n d 3 t h a n in 1 a n d 5. T h e s e differences are n o t as clear as t h o s e in (1). T h e y m a y , n o n e t h e less, b e s i m i l a r l y signific a n t . No a t t e m p t was m a d e in t h i s e x p e r i m e n t to q u a n t i t a r e t h e s t a i n i n g i n t e n s i t y of t h e b a n d s or t o f u r t h e r i d e n t i f y t h e a p o p r o t e i n s w h i c h give rise to t h e s e b a n d s . Discussion. W e believe t h a t t h e f i n d i n g t h a t o n l y a s m a l l n u m b e r of V L D L a p o p r o t e i n s increases signific a n t l y following food i n t a k e a n d t h a t t h e c o n c e n t r a t i o n s of t h e m a j o r i t y of t h e a p o p r o t e i n s r e m a i n s u n a f f e c t e d is i n t e r e s t i n g a n d significant. Q u a l i t a t i v e as t h e p r e s e n t f i n d i n g s are, t h e y are q u i t e a d e q u a t e to exclude w h a t might appear to be the most plausible assumption about a p o p r o t e i n f u n c t i o n in lipid t r a n s p o r t , n a m e l y t h a t in r e s p o n s e t o food i n t a k e , s i m p l y m o r e of t h e same V L D L is p r o d u c e d as t h a t w h i c h is c i r c u l a t i n g in t h e f a s t i n g
]~XPERIENTIA31/10
state. N e w l y f o r m e d V L D L following food i n t a k e obviously has a different apoprotein composition than V L D L p r e s e n t in t h e f a s t i n g state. Some of t h e q u e s t i o n s w h i c h arise are: W h a t is t h e origin of t h e s e n e w a p o p r o t e i n ? Are t h e y n e w l y s y n t h e sized p r o t e i n s , p e r h a p s s y n t h e s i z e d in t h e gut, or are t h e y some of t h e m i n o r h i g h d e n s i t y a p o p r o t e i n s ? W h a t k i n d s of l i p o p r o t e i n molecules c a r r y t h e s e a p o p r o t e i n s ? Are t h e s e a p o p r o t e i n s c a r r i e d as special s u b p o p u l a t i o n s 14,1~,17 ? Are e a c h of t h e a p o p r o t e i n s or s u b p o p u l a t i o n s u n d e r i n d e p e n d e n t m e t a b o l i c c o n t r o l or is t h e c o n t r o l of c e r t a i n of t h e m l i n k e d ? T h e s e q u e s t i o n s will remain open until the apoproteins and snbpopulations are isolated a n d c h a r a c t e r i z e d so t h a t q u a n t i t a t i v e m e t a b o l i c s t u d i e s c a n b e c a r r i e d out.
Summary. T h e c o n c e n t r a t i o n s of c e r t a i n of t h e v e r y low d e n s i t y h u m a n s e r u m l i p o p r o t e i n a p o p r o t e i n s were f o u n d to increase following a meal, while t h e c o n c e n t r a t i o n s of t h e m a j o r i t y of t h e a p o p r o t e i n s were f o u n d to b e unaffected. j . MILLER a n d F. ALADJEM ls
is j. ALBERS and F. ALADJEM, Biochemistry IO, 3436 (1971). 17 ]~. PEARLSTEIN and F. ALADJEM, Bioehem. Med. 8, 28 (1973).
as This work was supported by grants from the U.S. Public Health Service.
Effect of Sex Hormones
on Uric Acid Metabolism
I t h a s b e e n k n o w n for m a n y y e a r s t h a t t h e a v e r a g e s e r u m u r a t e c o n c e n t r a t i o n of p r e - m e n o p a u s a l females is a p p r o x i m a t e l y 1.0 m g p e r 100 m l lower t h a n t h a t of m a l e s 1. T h e e x i s t e n c e of t h i s sex difference in s e r u m u r a t e concentration has been attributed to the hormonal a l t e r a t i o n f o u n d b e t w e e n b o t h sexes. T h e p u r p o s e of t h i s s t u d y is t o e v a l u a t e t h e effect of some sex h o r m o n e s o n u r a t e m e t a b o l i s m in a n i m a l e x p e r i m e n t s . Methods and materials. W i s t a r r a t s w e i g h i n g 150-200 g were used in t h e p r e s e n t s t u d y . P l a s m a a n d u r i n a r y uric acid c o n c e n t r a t i o n were e s t i m a t e d , u s i n g a n e n z y m i c s p e c t r o p h o t o m e t r i c m e t h o d of LIDDLE 2. A l l a n t o i n was m e a s u r e d b y t h e m e t h o d of LARSON a. B l o o d s a m p l e s were t a k e n before a n d a f t e r t h e c o m p l e t i o n of t h e d a i l y a d m i n i s t r a t i o n of sex h o r m o n e s . 24-hour u r i n e s a m p l e s were collected in e v e r y g r o u p d u r i n g successive 7 d a y s before a n d a f t e r t h e a d m i n i s t r a t i o n of h o r m o n e s . E s t r o gen or p r o g e s t e r o n e were a d m i n i s t e r e d to f e m a l e r a t s a n d a n d r o g e n to m a l e rats. T h e d a i l y doses of estrogen, p r o g e s t e r o n e a n d a n d r o g e n i.m. were 10 nag, 100 m g a n d 100 m g / k g b o d y weight, respectively. T h e s e h o r m o n e s were d a i l y a d m i n i s t e r e d for 7 days. B l o o d s a m p l e s were a n a l y z e d for c o n c e n t r a t i o n of uric acid. U r i n a r y e x c r e t i o n of uric acid a n d a l l a n t o i n were m e a s u r e d a n d c a l c u l a t e d in 24-hour u r i n e samples. Results. T h e r e s u l t s of t h e p r e s e n t s t u d y are s u m m a r i z e d in t h e Table. W h e n 100 m g / k g b o d y w e i g h t e s t r o g e n was g i v e n d a i l y for 7 d a y s in f e m a l e rats, t h e m e a n p l a s m a u r a t e level (1.85 4- 0.76 m g / 1 0 0 ml) a n d t h e m e a n e x c r e t i o n of uric acid plus a l l a n t o i n (72.89 4- 11.54 m g / day) d i d n o t c h a n g e (1.87 4- 0.93 rag/100 ml, 75.17 411.72 rag/day). O n i n j e c t i o n of a n d r o g e n , 10 rng/kg b o d y w e i g h t in m a l e rats, t h e m e a n p l a s m a u r a t e level was s l i g h t l y e l e v a t e d f r o m 2.10 4- 0.81 m g / 1 0 0 m l t o 2.24 4- 0.84 rag/ 100 m l a n d t h e m e a n u r i n a r y e x c r e t i o n of uric acid plus a l l a n t o i n was s l i g h t l y increased f r o m 73.73 4- 14.33 m g /
Department o/ Microbiology, University o/ Southern California School o/Medicine, 2025 Zonal Avenue, Los Angeles (Cali/ornia 90033, USA), 8 April 7975.
in Rats d a y t o 78.02 4- 14.65 m g / d a y . B u t t h e s e differences were n o t significant. T h e m e a n p l a s m a u r a t e c o n c e n t r a t i o n was s i g n i f i c a n t l y r e d u c e d f r o m 2.43 4- 1.04 rag/100 m l t o 1.53 4- 0.57 rag/ 100 m l a n d t h e m e a n u r i n a r y e x c r e t i o n of uric acid plus a l l a n t o i n d e c r e a s e d f r o m 60.15 4- 19.81 m g / d a y to 54.71 4- 16.56 r a g / d a y b y t h e i n j e c t i o n of p r o g e s t e r o n e 100 m g / k g b o d y w e i g h t in female rats. Discussion. I t is well r e c o g n i z e d t h a t p l a s m a u r a t e levels reilect b o t h de n o v o p u r i n e s y n t h e s i s a n d r e n a l e x c r e t i o n of uric acid. I t is also g e n e r a l l y a c c e p t e d t h a t p l a s m a u r a t e levels in c h i l d r e n do n o t differ b e t w e e n b o t h sexes 1. I n p r e - m e n o p a u s a l a d u l t w o m e n , p l a s m a u r a t e levels are a b o u t 1.0 m g / 1 0 0 m l lower t h a n t h o s e of men, a n d t h e y are g r a d u a l l y i n c r e a s e d in m e n o p a u s e . T h i s age a n d sex difference in u r a t e m e t a b o l i s m suggests e n d o c r i n e a l t e r a t i o n s in m e n . MIKKELSEN e t al. 1 s h o w e d in p o p u l a t i o n studies in T e c u m s e h t h a t t h e p l a s m a u r a t e levels in p r e g n a n t w o m e n were s i g n i f i c a n t l y lower t h a n t h o s e of agematched non-pregnant women. From these findings they suggested that estrogen and/or progesterone may have u r a t e - d e p r e s s i n g ability. Similar o b s e r v a t i o n s were r e p o r t e d b y BOYLE e t al. 4. T h e y s t u d i e d t h e i n f l u e n c e of pregnancy on urate metabolism and confirmed that the s e r u m u r a t e levels are s i g n i f i c a n t l y lower d u r i n g e a r l y a n d m i d d l e p r e g n a n c y t h a n t h o s e of a g e - m a t c h e d f e m a l e controls. T h e y s h o w e d t h a t t h e u r a t e e x c r e t i o n was i n c r e a s e d in m i d d l e a n d l a t e p r e g n a n c y . T h e y c o n s i d e r 1 W. M. ~/J[IKKELSEN, H. J. DODGE and H. VALKI~NBURG,Am. J.
Med. 39, 242 (1965). 2 L. LIDDLE, J. E. SEEGlVilLLER and L. EASTER, J. Lab. clin. Med.
54, 903 (1959). z H. W. LARSON, J. biol. Chem. 9d, 727 (1931). J. A. BOYLE, S. CAMeBELL,A. M. DU~CCA~,W. R. GREIGand W. W. BUCHANAn, J. olin. Path. 19, 501 (1966).
15.10. 1975
Specialia
1135
The influence of the i.m. administration of sex hormones in rats on plasma urate levels and urinary excretion of uric acid and allantoin Hormones
No. of animals
Androgeu (10 mg/kg/day)
16
Progesterone (100 mg/kg/day)
13
Estrogen (100 mg/kg/day)
13
Plasma urate level (mg/100 ml)
before after before after before after
2.10 =E 0.81 2.24 4- 0.84 2.43 4- 1.04 1.53 ~2 0.57 ~ 1.85 ~ 0.76 1.87 • 0.93
Urinary excretion Uric acid (mg/day)
Allantoin (mglday)
1.73 J= 1.93 1.82 4- 0.55 1,25 4- 0.21 1,21 4- 0.26 1.99 ~ 0.24 1.97 ! 0.61
72.6 5[2 12.4 75.2 ~ 14.1 58.9 2~ 19.6 53.5 ~= 16.3 70.9 ~= 11.3 73.2 ~2 11.1
~p < 0.05. Plasma urate levels were average values =t- SD of animals. Urinary excretion were shown by average values ~ SD of successioi~ 7 days.
t h a t t h e renal clearance of u r a t e is increased in p r e g n a n c y a n d t h e e n h a n c e d r e n a l e x c r e t i o n of uric acid a n d / o r h y p e r v o l a e m i a of p r e g n a n c y m a y result in t h e h y p o uricemia. H o w e v e r , in e a r l y p r e g n a n c y t h e y could n o t s h o w a n y c h a n g e in r e n a l e x c r e t i o n of uric acid. R e c e n t l y NICHOLLS el: al. ~ e x a m i n e d t h e effect of e s t r o g e n on p l a s m a a n d u r i n a r y uric acid in t r a n s - s e x u a l men, a n d s h o w e d t h a t stilboestrol increases t h e renal e x c r e t i o n of uric acid a n d lowers t h e p l a s m a u r a t e level. T h e y suggested t h a t uricosuric a c t i o n of stilboestrol is a possible cause for age a n d sex differences in p l a s m a uric acid. I n rats, t h e e n d p r o d u c t of p u r i n e m e t a b o l i s m is allant o i n a n d is e x c r e t e d in u r i n e in large a m o u n t s t h o u g h u r i n a r y e x c r e t i o n of uric acid is v e r y little. Therefore, it is difficult to e s t i m a t e t h e renal clearance of uric acid exactly. The p r e s e n t s t u d y s e e m e d to i n d i c a t e t h a t e s t r o g e n h a s no influence on u r a t e p r o d u c t i o n a n d on t h e r e n a l clearance of uric acid. H o w e v e r , it c a n n o t be d e n i e d t h a t e s t r o g e n m a y influence uric acid excretion. W e d e m o n s t r a t e d t h a t p l a s m a u r a t e c o n c e n t r a t i o n and u r i n a r y e x c r e t i o n of uric acid plus allantoin was r e d u c e d b y p r o g e s t e r o n e , a n d t h e r e f o r e it could be a s s u m e d t h a t progesterone diminishes purine synthesis and this effect of p r o g e s t e r o n e would a p p e a r to e x p l a i n t h e sex difference in u r a t e levels in adults. ACH>=SON6 s h o w e d p r e v i o u s l y a significant positive corr e l a t i o n b e t w e e n s e r u m uric acid a n d h a e m o g l o b i n levels in h e a l t h y a d u l t s a n d s u g g e s t e d t h a t t h e sex difference in
u r a t e m e t a b o l i s m m a y be r e l a t e d t o t h e difference in t u r n - o v e r r a t e of blood ceils in b o t h sexes. MIKKELSEN e t al. f o u n d t h a t in male s u b j e c t s t h e p l a s m a u r a t e levels s h o w e d a m a r k e d rise a t t h e p u b e r t y a n d s p e c u l a t e d t h a t a n d r o g e n m a y p l a y an i m p o r t a n t role in raising t h e p l a s m a u r a t e levels. H o w e v e r , we could n o t c o n f i r m t h i s h y p o t h esis in t h e p r e s e n t s t u d y , a n d f u r t h e r e x p e r i m e n t s will h a v e to be carried o u t t o clarify t h e effect of a n d r o g e n on purine metabolism.
Summary. T h e effects of sex h o r m o n e s on p u r i n e m e t a b o l i s m were i n v e s t i g a t e d in rats. N o influence on p u r i n e s y n t h e s i s was s h o w n b y t h e i n j e c t i o n of e s t r o g e n a n d androgen. The p l a s m a u r a t e levels were s i g n i f i c a n t l y lowered f r o m 2.43 • 1.04 mg/100 m l to 1.53 i 0.57 m g / 100 m i b y t h e i n j e c t i o n of p r o g e s t e r o n e . U r i n a r y e x c r e t i o n of uric acid plus a l l a n t o i n was s l i g h t l y r e d u c e d . T h e s e results s u g g e s t e d t h a t p r o g e s t e r o n e m a y influence age a n d sex differences in h u m a n p l a s m a u r a t e levels. Y. NISHIDA, I. AKAOKA a n d T. NISHIZAWA
1)epartment o/Medicine and Physical Therapy, Faculty o] Medicine, University of Tokyo, Bunkyo-ku, Tokyo (Japan 713), 3 June 7975. 5 A. NICIlOLLS,M. L. SNAITIt and J. T. SCOTT, Br. reed. J. 1,449 (1973). 6 R. M. ACHESOSand W. M. O'BRIEX, Lancet 2, 777 (1966).
T h e E f f e c t of H u n g e r o n F r e e F a t t y A c i d a n d C o r t i c o s t e r o n e P l a s m a L e v e l s i n R a t s F a t t y acids p r o v i d e a n e n e r g y source c a p a b l e of r a p i d m o b i l i z a t i o n for n e a r l y all of an o r g a n i s m tissues. T h e y are s t o r e d in t h e adipose tissue as t r i g l y c e r i d e s a n d are set free b y lipolysis. W h e n t h e o r g a n i s m r e q u i r e s m o r e e n e r g y t h a n is available f r o m its diet, or f r o m liver or muscle glycogen, m o b i l i z a t i o n of f a t t y acids is increased 1, 2. The h o r m o n e s of t h e p i t u i t a r y gland a n d t h e a d r e n a l c o r t e x p l a y a n i m p o r t a n t role in t h e m o b i l i z a t i o n of f a t in f a s t i n g a n i m a l s 1,a-~. This i n v e s t i g a t i o n deals w i t h t h e c h a n g e s w i t h time in t h e p l a s m a c o n c e n t r a t i o n s of free f a t t y acids (FFA) a n d c o r t i c o s t e r o n e in t h e case of f a s t i n g r a t s in c o m p a r i s o n w i t h n o r m a l l y fed controls. The d i u r n a l cycles of t h e a n i m a l s were t a k e n i n t o c o n s i d e r a t i o n . Also, t h e effect of h y p o x i a on t h e c o n c e n t r a t i o n c h a n g e s of t h e F F A was investigated.
Material and methods. Male W i s t a r r a t s (160-200 g) were fed a s t a n d a r d d i e t ( R a t b i s c u i t f r o m t h e Tagger Co., Graz) for 4 weeks before t h e s t a r t of testing. The feed c o n t a i n e d 59.5% c a r b o h y d r a t e s , 21.7% p r o t e i n , 2.6% fats, a n d was e n r i c h e d w i t h v i t a m i n s a n d minerals. I n all tests, w a t e r was available t o t h e a n i m a l s ad l i b i t u m . T h e s a m e a n i m a l s were used for all e x p e r i m e n t s . Once a 1 G. F. CAHILL JR., ~V[.G. HERRERA, A. P. MORGAN, J. S. SOELDNER, J. STEINKE, P. L. LEVY, G. A. DxEICHARD JR. and D. lV[. KIv~is,
J. din. Invest. ~5, 1751 (1966). 2 D. S. FREDRICKSONand R. S. GORDON JR., Physiol. Rev. 38, 585 (1958). 3 j. N. FAIN, Endocrinology 71,633 (1962). 4 H..'VI. GOODMANand E. KNOI~IL, Am. J. Physiol. 201, 1 (1961). .5 R. O. Scow and S. S. CHERNICK, Ain. J. Physiol. 270, 1 (1966).
Speeialia
i n d i v i d u a l , i.e., 2 h a f t e r t h e m e a l ; in t h e l a t e r s a m p l e s t h e i n t e n s i t y of t h a t b a n d t h e n decreases p r o g r e s s i v e l y w i t h t i m e following e a t i n g s u c h t h a t i t h a s or h a s n e a r l y r e t u r n e d t o b a s e line level in s a m p l e No. 5. 2. T h e r e are differences in t h e a p o p r o t e i n b a n d s in t h e region b e t w e e n p H 6.5 a n d 7.5 b e t w e e n t h e pre- a n d p o s t e a t i n g samples. More i n t e n s e l y s t a i n i n g b a n d s occur in s a m p l e s 2 a n d 3 t h a n in 1 a n d 5. T h e s e differences are n o t as clear as t h o s e in (1). T h e y m a y , n o n e t h e less, b e s i m i l a r l y signific a n t . No a t t e m p t was m a d e in t h i s e x p e r i m e n t to q u a n t i t a r e t h e s t a i n i n g i n t e n s i t y of t h e b a n d s or t o f u r t h e r i d e n t i f y t h e a p o p r o t e i n s w h i c h give rise to t h e s e b a n d s . Discussion. W e believe t h a t t h e f i n d i n g t h a t o n l y a s m a l l n u m b e r of V L D L a p o p r o t e i n s increases signific a n t l y following food i n t a k e a n d t h a t t h e c o n c e n t r a t i o n s of t h e m a j o r i t y of t h e a p o p r o t e i n s r e m a i n s u n a f f e c t e d is i n t e r e s t i n g a n d significant. Q u a l i t a t i v e as t h e p r e s e n t f i n d i n g s are, t h e y are q u i t e a d e q u a t e to exclude w h a t might appear to be the most plausible assumption about a p o p r o t e i n f u n c t i o n in lipid t r a n s p o r t , n a m e l y t h a t in r e s p o n s e t o food i n t a k e , s i m p l y m o r e of t h e same V L D L is p r o d u c e d as t h a t w h i c h is c i r c u l a t i n g in t h e f a s t i n g
]~XPERIENTIA31/10
state. N e w l y f o r m e d V L D L following food i n t a k e obviously has a different apoprotein composition than V L D L p r e s e n t in t h e f a s t i n g state. Some of t h e q u e s t i o n s w h i c h arise are: W h a t is t h e origin of t h e s e n e w a p o p r o t e i n ? Are t h e y n e w l y s y n t h e sized p r o t e i n s , p e r h a p s s y n t h e s i z e d in t h e gut, or are t h e y some of t h e m i n o r h i g h d e n s i t y a p o p r o t e i n s ? W h a t k i n d s of l i p o p r o t e i n molecules c a r r y t h e s e a p o p r o t e i n s ? Are t h e s e a p o p r o t e i n s c a r r i e d as special s u b p o p u l a t i o n s 14,1~,17 ? Are e a c h of t h e a p o p r o t e i n s or s u b p o p u l a t i o n s u n d e r i n d e p e n d e n t m e t a b o l i c c o n t r o l or is t h e c o n t r o l of c e r t a i n of t h e m l i n k e d ? T h e s e q u e s t i o n s will remain open until the apoproteins and snbpopulations are isolated a n d c h a r a c t e r i z e d so t h a t q u a n t i t a t i v e m e t a b o l i c s t u d i e s c a n b e c a r r i e d out.
Summary. T h e c o n c e n t r a t i o n s of c e r t a i n of t h e v e r y low d e n s i t y h u m a n s e r u m l i p o p r o t e i n a p o p r o t e i n s were f o u n d to increase following a meal, while t h e c o n c e n t r a t i o n s of t h e m a j o r i t y of t h e a p o p r o t e i n s were f o u n d to b e unaffected. j . MILLER a n d F. ALADJEM ls
is j. ALBERS and F. ALADJEM, Biochemistry IO, 3436 (1971). 17 ]~. PEARLSTEIN and F. ALADJEM, Bioehem. Med. 8, 28 (1973).
as This work was supported by grants from the U.S. Public Health Service.
Effect of Sex Hormones
on Uric Acid Metabolism
I t h a s b e e n k n o w n for m a n y y e a r s t h a t t h e a v e r a g e s e r u m u r a t e c o n c e n t r a t i o n of p r e - m e n o p a u s a l females is a p p r o x i m a t e l y 1.0 m g p e r 100 m l lower t h a n t h a t of m a l e s 1. T h e e x i s t e n c e of t h i s sex difference in s e r u m u r a t e concentration has been attributed to the hormonal a l t e r a t i o n f o u n d b e t w e e n b o t h sexes. T h e p u r p o s e of t h i s s t u d y is t o e v a l u a t e t h e effect of some sex h o r m o n e s o n u r a t e m e t a b o l i s m in a n i m a l e x p e r i m e n t s . Methods and materials. W i s t a r r a t s w e i g h i n g 150-200 g were used in t h e p r e s e n t s t u d y . P l a s m a a n d u r i n a r y uric acid c o n c e n t r a t i o n were e s t i m a t e d , u s i n g a n e n z y m i c s p e c t r o p h o t o m e t r i c m e t h o d of LIDDLE 2. A l l a n t o i n was m e a s u r e d b y t h e m e t h o d of LARSON a. B l o o d s a m p l e s were t a k e n before a n d a f t e r t h e c o m p l e t i o n of t h e d a i l y a d m i n i s t r a t i o n of sex h o r m o n e s . 24-hour u r i n e s a m p l e s were collected in e v e r y g r o u p d u r i n g successive 7 d a y s before a n d a f t e r t h e a d m i n i s t r a t i o n of h o r m o n e s . E s t r o gen or p r o g e s t e r o n e were a d m i n i s t e r e d to f e m a l e r a t s a n d a n d r o g e n to m a l e rats. T h e d a i l y doses of estrogen, p r o g e s t e r o n e a n d a n d r o g e n i.m. were 10 nag, 100 m g a n d 100 m g / k g b o d y weight, respectively. T h e s e h o r m o n e s were d a i l y a d m i n i s t e r e d for 7 days. B l o o d s a m p l e s were a n a l y z e d for c o n c e n t r a t i o n of uric acid. U r i n a r y e x c r e t i o n of uric acid a n d a l l a n t o i n were m e a s u r e d a n d c a l c u l a t e d in 24-hour u r i n e samples. Results. T h e r e s u l t s of t h e p r e s e n t s t u d y are s u m m a r i z e d in t h e Table. W h e n 100 m g / k g b o d y w e i g h t e s t r o g e n was g i v e n d a i l y for 7 d a y s in f e m a l e rats, t h e m e a n p l a s m a u r a t e level (1.85 4- 0.76 m g / 1 0 0 ml) a n d t h e m e a n e x c r e t i o n of uric acid plus a l l a n t o i n (72.89 4- 11.54 m g / day) d i d n o t c h a n g e (1.87 4- 0.93 rag/100 ml, 75.17 411.72 rag/day). O n i n j e c t i o n of a n d r o g e n , 10 rng/kg b o d y w e i g h t in m a l e rats, t h e m e a n p l a s m a u r a t e level was s l i g h t l y e l e v a t e d f r o m 2.10 4- 0.81 m g / 1 0 0 m l t o 2.24 4- 0.84 rag/ 100 m l a n d t h e m e a n u r i n a r y e x c r e t i o n of uric acid plus a l l a n t o i n was s l i g h t l y increased f r o m 73.73 4- 14.33 m g /
Department o/ Microbiology, University o/ Southern California School o/Medicine, 2025 Zonal Avenue, Los Angeles (Cali/ornia 90033, USA), 8 April 7975.
in Rats d a y t o 78.02 4- 14.65 m g / d a y . B u t t h e s e differences were n o t significant. T h e m e a n p l a s m a u r a t e c o n c e n t r a t i o n was s i g n i f i c a n t l y r e d u c e d f r o m 2.43 4- 1.04 rag/100 m l t o 1.53 4- 0.57 rag/ 100 m l a n d t h e m e a n u r i n a r y e x c r e t i o n of uric acid plus a l l a n t o i n d e c r e a s e d f r o m 60.15 4- 19.81 m g / d a y to 54.71 4- 16.56 r a g / d a y b y t h e i n j e c t i o n of p r o g e s t e r o n e 100 m g / k g b o d y w e i g h t in female rats. Discussion. I t is well r e c o g n i z e d t h a t p l a s m a u r a t e levels reilect b o t h de n o v o p u r i n e s y n t h e s i s a n d r e n a l e x c r e t i o n of uric acid. I t is also g e n e r a l l y a c c e p t e d t h a t p l a s m a u r a t e levels in c h i l d r e n do n o t differ b e t w e e n b o t h sexes 1. I n p r e - m e n o p a u s a l a d u l t w o m e n , p l a s m a u r a t e levels are a b o u t 1.0 m g / 1 0 0 m l lower t h a n t h o s e of men, a n d t h e y are g r a d u a l l y i n c r e a s e d in m e n o p a u s e . T h i s age a n d sex difference in u r a t e m e t a b o l i s m suggests e n d o c r i n e a l t e r a t i o n s in m e n . MIKKELSEN e t al. 1 s h o w e d in p o p u l a t i o n studies in T e c u m s e h t h a t t h e p l a s m a u r a t e levels in p r e g n a n t w o m e n were s i g n i f i c a n t l y lower t h a n t h o s e of agematched non-pregnant women. From these findings they suggested that estrogen and/or progesterone may have u r a t e - d e p r e s s i n g ability. Similar o b s e r v a t i o n s were r e p o r t e d b y BOYLE e t al. 4. T h e y s t u d i e d t h e i n f l u e n c e of pregnancy on urate metabolism and confirmed that the s e r u m u r a t e levels are s i g n i f i c a n t l y lower d u r i n g e a r l y a n d m i d d l e p r e g n a n c y t h a n t h o s e of a g e - m a t c h e d f e m a l e controls. T h e y s h o w e d t h a t t h e u r a t e e x c r e t i o n was i n c r e a s e d in m i d d l e a n d l a t e p r e g n a n c y . T h e y c o n s i d e r 1 W. M. ~/J[IKKELSEN, H. J. DODGE and H. VALKI~NBURG,Am. J.
Med. 39, 242 (1965). 2 L. LIDDLE, J. E. SEEGlVilLLER and L. EASTER, J. Lab. clin. Med.
54, 903 (1959). z H. W. LARSON, J. biol. Chem. 9d, 727 (1931). J. A. BOYLE, S. CAMeBELL,A. M. DU~CCA~,W. R. GREIGand W. W. BUCHANAn, J. olin. Path. 19, 501 (1966).
15.10. 1975
Specialia
1135
The influence of the i.m. administration of sex hormones in rats on plasma urate levels and urinary excretion of uric acid and allantoin Hormones
No. of animals
Androgeu (10 mg/kg/day)
16
Progesterone (100 mg/kg/day)
13
Estrogen (100 mg/kg/day)
13
Plasma urate level (mg/100 ml)
before after before after before after
2.10 =E 0.81 2.24 4- 0.84 2.43 4- 1.04 1.53 ~2 0.57 ~ 1.85 ~ 0.76 1.87 • 0.93
Urinary excretion Uric acid (mg/day)
Allantoin (mglday)
1.73 J= 1.93 1.82 4- 0.55 1,25 4- 0.21 1,21 4- 0.26 1.99 ~ 0.24 1.97 ! 0.61
72.6 5[2 12.4 75.2 ~ 14.1 58.9 2~ 19.6 53.5 ~= 16.3 70.9 ~= 11.3 73.2 ~2 11.1
~p < 0.05. Plasma urate levels were average values =t- SD of animals. Urinary excretion were shown by average values ~ SD of successioi~ 7 days.
t h a t t h e renal clearance of u r a t e is increased in p r e g n a n c y a n d t h e e n h a n c e d r e n a l e x c r e t i o n of uric acid a n d / o r h y p e r v o l a e m i a of p r e g n a n c y m a y result in t h e h y p o uricemia. H o w e v e r , in e a r l y p r e g n a n c y t h e y could n o t s h o w a n y c h a n g e in r e n a l e x c r e t i o n of uric acid. R e c e n t l y NICHOLLS el: al. ~ e x a m i n e d t h e effect of e s t r o g e n on p l a s m a a n d u r i n a r y uric acid in t r a n s - s e x u a l men, a n d s h o w e d t h a t stilboestrol increases t h e renal e x c r e t i o n of uric acid a n d lowers t h e p l a s m a u r a t e level. T h e y suggested t h a t uricosuric a c t i o n of stilboestrol is a possible cause for age a n d sex differences in p l a s m a uric acid. I n rats, t h e e n d p r o d u c t of p u r i n e m e t a b o l i s m is allant o i n a n d is e x c r e t e d in u r i n e in large a m o u n t s t h o u g h u r i n a r y e x c r e t i o n of uric acid is v e r y little. Therefore, it is difficult to e s t i m a t e t h e renal clearance of uric acid exactly. The p r e s e n t s t u d y s e e m e d to i n d i c a t e t h a t e s t r o g e n h a s no influence on u r a t e p r o d u c t i o n a n d on t h e r e n a l clearance of uric acid. H o w e v e r , it c a n n o t be d e n i e d t h a t e s t r o g e n m a y influence uric acid excretion. W e d e m o n s t r a t e d t h a t p l a s m a u r a t e c o n c e n t r a t i o n and u r i n a r y e x c r e t i o n of uric acid plus allantoin was r e d u c e d b y p r o g e s t e r o n e , a n d t h e r e f o r e it could be a s s u m e d t h a t progesterone diminishes purine synthesis and this effect of p r o g e s t e r o n e would a p p e a r to e x p l a i n t h e sex difference in u r a t e levels in adults. ACH>=SON6 s h o w e d p r e v i o u s l y a significant positive corr e l a t i o n b e t w e e n s e r u m uric acid a n d h a e m o g l o b i n levels in h e a l t h y a d u l t s a n d s u g g e s t e d t h a t t h e sex difference in
u r a t e m e t a b o l i s m m a y be r e l a t e d t o t h e difference in t u r n - o v e r r a t e of blood ceils in b o t h sexes. MIKKELSEN e t al. f o u n d t h a t in male s u b j e c t s t h e p l a s m a u r a t e levels s h o w e d a m a r k e d rise a t t h e p u b e r t y a n d s p e c u l a t e d t h a t a n d r o g e n m a y p l a y an i m p o r t a n t role in raising t h e p l a s m a u r a t e levels. H o w e v e r , we could n o t c o n f i r m t h i s h y p o t h esis in t h e p r e s e n t s t u d y , a n d f u r t h e r e x p e r i m e n t s will h a v e to be carried o u t t o clarify t h e effect of a n d r o g e n on purine metabolism.
Summary. T h e effects of sex h o r m o n e s on p u r i n e m e t a b o l i s m were i n v e s t i g a t e d in rats. N o influence on p u r i n e s y n t h e s i s was s h o w n b y t h e i n j e c t i o n of e s t r o g e n a n d androgen. The p l a s m a u r a t e levels were s i g n i f i c a n t l y lowered f r o m 2.43 • 1.04 mg/100 m l to 1.53 i 0.57 m g / 100 m i b y t h e i n j e c t i o n of p r o g e s t e r o n e . U r i n a r y e x c r e t i o n of uric acid plus a l l a n t o i n was s l i g h t l y r e d u c e d . T h e s e results s u g g e s t e d t h a t p r o g e s t e r o n e m a y influence age a n d sex differences in h u m a n p l a s m a u r a t e levels. Y. NISHIDA, I. AKAOKA a n d T. NISHIZAWA
1)epartment o/Medicine and Physical Therapy, Faculty o] Medicine, University of Tokyo, Bunkyo-ku, Tokyo (Japan 713), 3 June 7975. 5 A. NICIlOLLS,M. L. SNAITIt and J. T. SCOTT, Br. reed. J. 1,449 (1973). 6 R. M. ACHESOSand W. M. O'BRIEX, Lancet 2, 777 (1966).
T h e E f f e c t of H u n g e r o n F r e e F a t t y A c i d a n d C o r t i c o s t e r o n e P l a s m a L e v e l s i n R a t s F a t t y acids p r o v i d e a n e n e r g y source c a p a b l e of r a p i d m o b i l i z a t i o n for n e a r l y all of an o r g a n i s m tissues. T h e y are s t o r e d in t h e adipose tissue as t r i g l y c e r i d e s a n d are set free b y lipolysis. W h e n t h e o r g a n i s m r e q u i r e s m o r e e n e r g y t h a n is available f r o m its diet, or f r o m liver or muscle glycogen, m o b i l i z a t i o n of f a t t y acids is increased 1, 2. The h o r m o n e s of t h e p i t u i t a r y gland a n d t h e a d r e n a l c o r t e x p l a y a n i m p o r t a n t role in t h e m o b i l i z a t i o n of f a t in f a s t i n g a n i m a l s 1,a-~. This i n v e s t i g a t i o n deals w i t h t h e c h a n g e s w i t h time in t h e p l a s m a c o n c e n t r a t i o n s of free f a t t y acids (FFA) a n d c o r t i c o s t e r o n e in t h e case of f a s t i n g r a t s in c o m p a r i s o n w i t h n o r m a l l y fed controls. The d i u r n a l cycles of t h e a n i m a l s were t a k e n i n t o c o n s i d e r a t i o n . Also, t h e effect of h y p o x i a on t h e c o n c e n t r a t i o n c h a n g e s of t h e F F A was investigated.
Material and methods. Male W i s t a r r a t s (160-200 g) were fed a s t a n d a r d d i e t ( R a t b i s c u i t f r o m t h e Tagger Co., Graz) for 4 weeks before t h e s t a r t of testing. The feed c o n t a i n e d 59.5% c a r b o h y d r a t e s , 21.7% p r o t e i n , 2.6% fats, a n d was e n r i c h e d w i t h v i t a m i n s a n d minerals. I n all tests, w a t e r was available t o t h e a n i m a l s ad l i b i t u m . T h e s a m e a n i m a l s were used for all e x p e r i m e n t s . Once a 1 G. F. CAHILL JR., ~V[.G. HERRERA, A. P. MORGAN, J. S. SOELDNER, J. STEINKE, P. L. LEVY, G. A. DxEICHARD JR. and D. lV[. KIv~is,
J. din. Invest. ~5, 1751 (1966). 2 D. S. FREDRICKSONand R. S. GORDON JR., Physiol. Rev. 38, 585 (1958). 3 j. N. FAIN, Endocrinology 71,633 (1962). 4 H..'VI. GOODMANand E. KNOI~IL, Am. J. Physiol. 201, 1 (1961). .5 R. O. Scow and S. S. CHERNICK, Ain. J. Physiol. 270, 1 (1966).
