Gonadal and Age-Related Influences on NMDA-Induced Growth Hormone Secretion in Male Rats

1999 ◽  
Vol 69 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Leonor Pinilla ◽  
Lucas Gonzalez ◽  
Manuel Tena-Sempere ◽  
Carlos Dieguez ◽  
Enrique Aguilar
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Male Rats ◽  
Age Related

6-Hydroxydopamine Lesions of the Locus Coeruleus Induce a Paradoxical Increase in Growth Hormone Secretion in Male Rats

1992 ◽  
Vol 4 (1) ◽  
pp. 9-14 ◽  
Author(s):  
M. T. Bluet-Pajot ◽  
F. Mounier ◽  
D. Durand ◽  
C. Kordon ◽  
C. Llorens-Cortes ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Locus Coeruleus ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Male Rats ◽  
6 Hydroxydopamine

EFFECTS OF STILBOESTROL ON GROWTH HORMONE SECRETION AND PITUITARY CELL PROLIFERATION IN THE MALE RAT

1971 ◽  
Vol 51 (3) ◽  
pp. 473-481 ◽  
Author(s):  
H. M. LLOYD ◽  
J. D. MEARES ◽  
JOAN JACOBI ◽  
FRANCES J. THOMAS
Keyword(s):  
Growth Hormone ◽  
Cell Proliferation ◽  
Mitotic Activity ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Mean Value ◽  
Pituitary Cell ◽  
Male Rats ◽  
Male Rat ◽  
Serum Growth Hormone

SUMMARY A single 12 mg dose of stilboestrol dipropionate given to 100-day-old male rats resulted in increased pituitary mitotic activity, pituitary weight and serum growth hormone; the latter rose from a mean value of 20 ng/ml to a maximum of 342 ng/ml 9 days later. Serum growth hormone and pituitary mitotic activity then gradually diminished but were still slightly increased on day 28. Serum growth hormone and pituitary weight were significantly correlated during the periods of rapidly rising and of sustained high levels of serum growth hormone. Indices of mitotic activity were correlated with serum growth hormone during the periods of rapidly rising and of falling levels of serum growth hormone.

Transgenic growth hormone mice exposed to lifetime constant illumination: gender-specific effects

2004 ◽  
Vol 82 (6) ◽  
pp. 950-965 ◽  
Author(s):  
M L Perreault ◽  
C D Rollo
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Control Group ◽  
Differential Growth ◽  
Lower Growth ◽  
Laboratory Rats ◽  
Specific Effects ◽  
Age Related ◽  
Gender Specific

Photoperiod affects most of the features altered in transgenic growth hormone (TG) mice, and laboratory rats and mice retain some sensitivity to photoperiod. We examined growth, feeding, longevity, and reproduction of TG mice and normal control mice (Mus musculus L., 1758) in 12 h light : 12 h dark (LD) and 24 h light (LL) photoperiods. Sexual dichotomy in growth and hepatic gene expression are considered to require gender-specific patterns of growth hormone secretion that are absent in TG mice. Regardless, in the LD photoperiod mature TG females were 82.8% (46.8 g) of the mass of TG males (56.5 g, p < 0.05), whereas control mice showed no size dichotomy (≈33 g). Mature masses of TG males and of control mice of either gender were unaffected by the LL photoperiod. TG females, however, reached a mature mass 92% (50.9 g) of that of mature TG males in the LL photoperiod, attenuating the sexual size dichotomy expressed in the LD photoperiod. Growth of females was slower than that of males, even in the control group. TG females in the LL photoperiod expressed faster growth, higher reproduction, and greater mean longevity than TG females in the LD photoperiod. Differences in age-related feeding associated with gender and photoperiod reflected differential growth rates. Females grew more slowly and ate more than males of similar age because they were smaller (i.e., had lower growth efficiencies). The LL photoperiod improved the energy balance of TG females. Possible mechanisms mediating such gender-specific effects are explored.

Age-related blunting of growth hormone secretion during exercise may not be solely due to increased somatostatin tone

Metabolism ◽  
1999 ◽  
Vol 48 (5) ◽  
pp. 665-670 ◽  
Author(s):  
Taylor J. Marcell ◽  
Robert A. Wiswell ◽  
Steve A. Hawkins ◽  
Kyle M. Tarpenning
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Age Related

Negative feedback of insulin-like growth factor-I on growth hormone secretion by porcine pituitary cells

1995 ◽  
Vol 75 (1) ◽  
pp. 57-61 ◽  
Author(s):  
C. Farmer ◽  
H. Lapierre
Keyword(s):  
Growth Hormone ◽  
Negative Feedback ◽  
Culture Media ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Late Gestation ◽  
Pituitary Cells ◽  
Gh Secretion ◽  
Age Related ◽  
Igf I

Pituitaries from female Yorkshire pig fetuses (90 d, n = 26; 110 d, n = 17) and 6-mo-old pigs (n = 5) were enzymatically dispersed, plated, and cultured for 47 h. The cells were then rinsed and incubated for 22 h with testing media containing 0, 50, 100, 200, 300 or 400 ng mL−1 of IGF-I. Half of the wells from each concentration of IGF-I were then incubated for an additional 3 h with concentrations of IGF-I similar to those in the previous incubation, while the other half also had GRF added to the testing media to reach a final concentration of 10−8 M. Culture media were then collected from all the wells, were frozen, and later assayed for GH. Irrespective of whether GRF was present, IGF-I decreased pituitary secretion of GH (P < 0.001). A significant negative response to IGF-I was already present at the dose of 50 ng mL−1 (P < 0.0001). However, the extent of the GH response to IGF-I seen in pigs of various ages differed depending on whether GRF was present. The present results therefore establish that IGF-I does exert a negative feedback on pituitary GH secretion in swine and that the age-related changes in this feedback are dependent on the presence of GRF. In swine, it appears that high circulating concentrations of GH in late-gestation fetuses are not a result of a lesser sensitivity of the somatotroph to the inhibitory actions of IGF-I. Key words: Pig, cell culture, pituitary, IGF-I, growth hormone, age

AGE-RELATED BLUNTING OF GROWTH HORMONE SECRETION IN MEN IS NOT DUE SOLELY TO INCREASED SOMATOSTATIN TONE

1998 ◽  
Vol 30 (Supplement) ◽  
pp. 106
Author(s):  
T. J. Marcell ◽  
R. A. Wiswell ◽  
S. A. Hawkins ◽  
K. T. Tarpenning
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Age Related

Effect of intermittent infusions of somatostatin on growth hormone secretion in unrestrained male rats with hypothalamic deafferentation

1990 ◽  
Vol 509 (2) ◽  
pp. 293-298 ◽  
Author(s):  
Shiro Minami ◽  
Ichiji Wakabayashi ◽  
Hitoshi Sugihara ◽  
Jun Kamegai ◽  
Osamu Hasegawa ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Male Rats ◽  
Hypothalamic Deafferentation

Adrenergic and Dopaminergic Control of Growth Hormone Secretion in Urethane Anesthetized Adult Male Rats

1978 ◽  
Vol 9 (4) ◽  
pp. 208-224 ◽  
Author(s):  
W. Ruch ◽  
P. Marbach ◽  
A.L. Jaton ◽  
B. Bucher ◽  
W. Doepfner
Keyword(s):  
Growth Hormone ◽  
Adult Male ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Male Rats ◽  
Dopaminergic Control
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