EFFETCS OF LH AND HCG ON THE METABOLISM OF THE PREPUBERTAL RAT OVARY: STIMULATION OF AMINO ACID TRANSPORT, PROTEIN SYNTHESIS, AND GLYCOLYSIS

1975 ◽  
Vol 78 (1) ◽  
pp. 122-134 ◽  
Author(s):  
Lars Nilsson ◽  
Gunnar Selstam
Keyword(s):  
Body Weight ◽  
Lactic Acid ◽  
Amino Acid ◽  
Acid Production ◽  
Lactic Acid Production ◽  
Amino Acid Uptake ◽  
Time Interval ◽  
Acid Uptake ◽  
Rat Ovary ◽  
Stimulation Of

ABSTRACT It has earlier been reported from this laboratory that FSH can stimulate amino acid uptake, protein synthesis and glycolysis in the isolated prepubertal rat ovary. In the present investigation the effects of LH and HCG were studied. The hormones were injected to prepubertal female rats, and the ovaries were extirpated for incubation in Krebs bicarbonate buffer 120 min later. Injection of 1 μg/100 g body weight of a bovine LH preparation (NIH-LH-B8) produced a significant increase in the in vitro uptake of [14C]α-amino-isobutyric acid ([14C]AIB) and [3H]leucine as well as of the incorporation of radioactivity into the ovarian protein. Higher doses (10 and 100 μg) of NIH-LH-B8 gave only minor further increases. Lactic acid production during the incubation period was also measured as a determination of the rate of glycolysis. Lactic acid production was stimulated by the LH injections with a clear dose-response between 0.1 and 10 μg/100 g body weight. The effects of LH were also investigated with shorter intervals between the injection of the hormone and the extirpation of the ovaries. While lactic acid production was maximally stimulated at a time interval of 30 min (the shortest time interval studied), 60 min was necessary for the stimulation of amino acid uptake and amino acid incorporation into protein. Injections of HCG mimicked the effects of LH on all parameters studied.

scholarly journals Insulin Stimulation of Amino Acid Uptake in Rat Diaphragm

1968 ◽  
Vol 243 (8) ◽  
pp. 1846-1853 ◽  
Author(s):  
L J Elsas ◽  
I Albrecht ◽  
L E Rosenberg
Keyword(s):  
Amino Acid ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Rat Diaphragm ◽  
Insulin Stimulation ◽  
Stimulation Of

Stimulation of Lactic Acid Production in Vitro from Prepubertal Rat Ovaries by Gonadotropins and Their Subunits1

Endocrinology ◽  
1973 ◽  
Vol 92 (4) ◽  
pp. 1022-1027 ◽  
Author(s):  
SUSAN WALKER FARMER ◽  
M. R. SAIRAM ◽  
HAROLD PAPKOFF
Keyword(s):  
Lactic Acid ◽  
Acid Production ◽  
Lactic Acid Production ◽  
Stimulation Of

scholarly journals Structural disruption of the trans-Golgi network does not interfere with the acute stimulation of glucose and amino acid uptake by insulin-like growth factor I in muscle cells

1994 ◽  
Vol 297 (2) ◽  
pp. 289-295 ◽  
Author(s):  
H S Hundal ◽  
P J Bilan ◽  
T Tsakiridis ◽  
A Marette ◽  
A Klip
Keyword(s):  
Amino Acid ◽  
Brefeldin A ◽  
Glucose Transporters ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Trans Golgi Network ◽  
Maximal Activation ◽  
Igf I ◽  
Golgi Network ◽  
Stimulation Of

The effects of insulin-like growth factor I (IGF-I) on glucose and amino acid uptake were investigated in fully differentiated L6 muscle cells, in order to determine whether the two processes are functionally related. Transport of both glucose and amino acid (methylaminoisobutyric acid, MeAIB) was activated rapidly in response to IGF-I. Stimulation reached a peak within 30 min and was sustained for up to 90 min. Maximal activation of either glucose or MeAIB transport was achieved at 3 nM IGF-I; the half-maximal activation (ED50) of glucose transport was at 107 pM and that of MeAIB transport was at 36 pM. Stimulation of amino acid uptake occurred in the absence or presence of glucose, suggesting that this response is not secondary to increased glucose intake. Incubation of cells for 1 h with Brefeldin A (5 micrograms/ml), which disassembles the Golgi apparatus and inhibits the secretory pathway in eukaryotic cells, had no effect on the acute IGF-I activation of glucose and MeAIB transport. Moreover, Brefeldin A caused wide redistribution of the trans-Golgi antigen TGN38, as assessed by subcellular fractionation, without affecting the distribution of glucose transporters. The finding that the degree of activation, time response and sensitivity to IGF-I and Brefeldin A were similar for both glucose and MeAIB transport suggests commonalities in the IGF-I mechanism of recruitment of glucose transporters and stimulation of amino acid transport through System A. An integral trans-Golgi network does not appear to be required for the acute IGF-I stimulation of glucose or amino acid transport, even though stimulation of glucose transport occurs through recruitment of glucose transporters from intracellular stores in these cells. We propose that the donor site of glucose transporters (and perhaps of amino acid transporters) involved in the acute response to IGF-I lies beyond the trans-Golgi network, perhaps in an endosomal compartment in close proximity to the plasma membrane.

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