Growth hormone response to different consecutive stress stimuli in healthy men: Is there any difference?

Figures & data

Figure 1 Growth hormone response to two consecutive stress stimuli: (A) exercise followed by exercise (n = 8), (B) insulin-induced hypoglycemia followed by insulin-induced hypoglycemia (n = 9), and (C) hyperthermia followed by hyperthermia (n = 8). The vertical bars (1A) symbolize the work loads during the bicycle ergometer exercise. The horizontal bars (1C) represent the exposure to a sauna. Two way RM ANOVA results are listed in the graphs. NS not significant, *p < 0.05, **p < 0.01 and ***p < 0.001 for timepoint vs. the respective baseline (start of the stimulus) values.

Table I.  Plasma glucose concentrations during two sequential insulin boluses (0.1 IU/kg i.v.) separated by 150 min.

Time (min)	Glucose (mmol/l)
	1st insulin test	2nd insulin test
0	5.05 ± 0.13	4.71 ± 0.21
30	1.89 ± 0.04*	2.27 ± 0.13*^†
45	2.83 ± 0.14*	2.94 ± 0.15*
60	3.25 ± 0.15*	3.52 ± 0.16*
90	3.83 ± 0.14*	4.25 ± 0.23^‡^†
120	4.30 ± 0.21*	4.37 ± 0.24

^† p ≤ 0.05 2nd insulin test vs. 1st insulin test at the same time-point

* p < 0.001

^‡ p < 0.05 timepoint vs. the respective baseline

Figure 2 Growth hormone response to two consecutive stimuli: (A) apomorphine administration followed by apomorphine administration (n = 8), (B) insulin-induced hypoglycemia followed by apomorphine administration (n = 9), and (C) apomorphine administration followed by insulin-induced hypoglycemia (n = 8). Two way RM ANOVA results are listed in the graphs. NS not significant, *p < 0.05, **p < 0.01 and ***p < 0.001 for time-point vs. the respective baseline (start of the stimulus) values.

Figure 3 Growth hormone response to GHRH administration under conditions associated with normal (room temperature, 22°C closed circles) and elevated (increased ambient temperature, 55°C open circles) baseline GH levels (n = 7). The horizontal bar represents the exposure to increased ambient temperature. Two way RM ANOVA results are listed in the graphs. *p < 0.05, **p < 0.01 and ***p < 0.001 for time-point vs. baseline (GHRH administration),+p < 0.05 and ++p < 0.01 room temperature vs. increased ambient temperature.