The plasma concentrations of secretin and vasoactive intestinal polypeptide (VIP) after long-term, strenuous exercise

Twelve subjects (aged 21-38 years) participated in a 90-km cross-country ski race lasting 4.45-6.50 h. In order to investigate a metabolic role for secretin and vasoactive intestinal polypeptide (VIP) during long-term strenuous exercise, seven of the subjects were given an oral hypertonic glucose solution while the others had no nutrient intake immediately after the race. The plasma concentrations of secretin and VIP were greatly increased immediately after the race, and the levels were not normalized within 140 min, though there was a significant decrease after 80 min with rest. The post-race plasma levels of secretin and VIP showed a rapid and very marked decrease 15 min after ingestion of glucose, and the plasma levels had returned to control levels 60 min and 15 min respectively after glucose loading. The results indicate some metabolic function for secretin and VIP during long-term physical exercise.

The effect of prolonged strain on serum levels of human pancreatic polypeptide and group I pepsinogens

Twenty-four young male subjects participated in a 5-day training course with long-term physical exercise (35% of VO2max), calorie supply deficiency (intake of approximately 6300 kJ/24 h, against a combustion of approximately 40,000 kJ/24 h), and severe sleep deprivation (2 h of sleep as a total during 5 days). The subjects were divided into three groups; one group (no. = 7) had no compensation for the stress factors, another group (no. = 8) compensated for the calorie deficiency, whereas a third group (no. = 9) partly compensated for the sleep deprivation. Fasting serum concentration of human pancreatic polypeptide (hPP) and group I pepsinogens (PGI) were measured immediately before the course, every morning during the course, and 8 h after the course. In addition, the serum response of hPP to a test meal was measured on day 3 during the course and in a control study performed 8 weeks later. The fasting serum concentration of hPP showed a two- to three-fold increase during the course in the low-caloric but not in the iso-caloric subjects. The serum concentration of hPP was decreased to pre-course levels after 8 h of rest. The postprandial hPP response was elevated in all the subjects during the course, with a greater increase in the low-caloric subjects than in the subjects with calorie balance. Serum concentration of PGI was 10-30% decreased during the course, and the levels were normalized after 8 h of rest after the course. The study shows that the function of the hPP cell and the chief cell is influenced by prolonged, multifactorial strain.(ABSTRACT TRUNCATED AT 250 WORDS)

The fasting levels and the postprandial response of gastroenteropancreatic hormones before and after prolonged fasting

The effect of a prolonged 5-day fast on the blood concentrations of vasoactive intestinal polypeptide (VIP), secretin, human pancreatic polypeptide (hPP), gastrin, and group I pepsinogens (PG I) was studied in 11 healthy subjects. During the fast there was a marked increase in the concentrations of VIP, secretin, and hPP, whereas the rise in the concentrations of gastrin and PG I was less pronounced. Refeeding suppressed the increased concentration of VIP and caused elevated postprandial concentrations of secretin and hPP, whereas starvation did not influence the postprandial release of gastrin and PG I. The study shows that prolonged starvation has a pronounced effect on gut endocrine responses.

Basal hyperchlorhydria and its relation to the plasma concentrations of secretin, vasoactive intestinal polypeptide (VIP) and gastrin during prolonged strain

Twenty young men divided into two groups participated in a five day training course with prolonged and heavy physical exercise, calorie supply deficiency and severe sleep deprivation. Basal acid output (BAO) was measured immediately after the course in seven of ten subjects who were given placebo tablets (placebo group) and in four of ten subjects who had a daily intake of 1 g cimetidine (cimetidine-group) during the course. Median BAO increased 3-fold in the placebo subjects (from 2.7 mmol/h to 8.2 mmol/h) but showed no increase in the cimetidine treated subjects. The median fasting plasma concentrations of secretin increased 2-8-fold during the course. Gastric suction for 1 h or ingestion of cimetidine reduced the plasma concentration of secretin by approx. 50%. Vasoactive intestinal polypeptide (VIP) increased 2-fold and was not influenced by reduction of gastric acid. The placebo group showed a small increase (P less than 0.05) in plasma concentration of gastrin on day two during the course. The study shows a marked hyperchlorhydria which partly explains the fasting hypersecretinemia found during prolonged strain. This strain-induced hyperchlorhydria could be abolished by treatment with the selective H2-receptor antagonist cimetidine.

The effect of sleep deprivation on the plasma levels of hormones during prolonged physical strain and calorie deficiency

The effect of sleep on the serum levels of hormones during prolonged heavy physical strain and calorie deficiency were investigated in 19 young men participating in a 5 day ranger training course with a calorie consumption of 35,000-50,000 kJ X 24 h-1, and a calorie intake of about 6,000 kJ X 24 h-1. The subjects were divided into two groups: the stress group (8 cadets) were allowed no organized sleep during the course, whereas the sleep group (9 cadets) had 3 h sleep each night. Small but significantly (p less than 0.01) higher serum levels were found in the sleep group compared to the stress group for cortisol, growth hormone and testosterone. No such differences were found for catecholamines, androstendione, dihydrotestosterone, LH, triiodothyronine and thyroxine. Androstendione and dihydrotestosterone decreased in parallel with testosterone (r = 0.5) during the course, changes which directly or indirectly seem to be due to decreased testicular secretion. The changes found during this investigation for the other hormones are similar to changes found during previous courses. LH showed only small variation during the course and cannot explain the decreased secretion from the testis or the difference between the two groups for testosterone. All hormones were normal within 23 days after the end of the course.

Increased plasma response of gastric inhibitory polypeptide to oral glucose and a liquid meal after prolonged starvation in healthy man

24 young, military subjects participated in a ranger training course of 5 days' duration with prolonged, heavy physical exercise and sleep deprivation. The subjects were divided into two groups showing either large calorie deficiency or nearly isocaloric status. An oral glucose tolerance test was performed on the subjects on day 5 on the course and in a control experiment 8 weeks after the course. During the course the subjects with negative calorie balance showed augmented integrated glucose-induced gastric inhibitory polypeptide (GIP) response (p less than 0.05) and the plasma concentration of GIP after glucose stimulation was higher at 90 and 120 min during the course than in the control experiment. On the other hand, the plasma GIP levels of the subjects on isocaloric diet changed similarly during the experimental period and the control period. In another experiment 11 healthy subjects were given a meal after an overnight fast and after 5 days of absolute fasting. The 5-day fast provoked higher postprandial plasma concentration of GIP between 60 and 150 min after meal stimulation, and the integrated meal-stimulated GIP response increased (p less than 0.01) after the prolonged fasting. The subjects in both experiments showed glucose intolerance. The insulinogenic index decreased during the training course, but increased during the prolonged, absolute fasting. The study shows that there is a dietary modulation of the GIP response to nutrient stimulation in healthy man and that the augmented GIP release is not attributable to insulin release.

Decreased serum levels of oestradiol, testosterone and prolactin during prolonged physical strain and sleep deprivation, and the influence of a high calorie diet

The changes in oestradiol, testosterone and prolactin, and the effects of a high calorie diet, were investigated in eleven young males cadets participating in a 5 days' ranger training course involving heavy and continuous physical activities with less than 1500 kcal . day-1 and almost without sleep. Prolactin decreased continuously during the first 24 h to 25% of precourse values. Testosterone decreased during the day time and reached below 25% of precourse values after 48 h. Oestradiol did not change during the first 48 h but then decreased to about 50% of precourse values. In conclusion, oestradiol, testosterone and prolactin are strongly reduced during prolonged strain. These changes were not reversed by a high calorie diet.

Secretin--a new stress hormone?

The plasma concentration of secretin was measured during a 5-day military training course comprising prolonged physical exercise (35% of max O2 uptake), severe caloric deficiency (approx. 35700 kJ/24 h) and sleep deprivation (only 2 h of sleep as a total during 5 days). 24 subjects were divided into 3 groups, one group was compensated for the caloric deficiency and another group was partly compensated for the sleep deprivation. The results showed that the fasting plasma secretin increased 3-6-fold (from 1.8-3.7 to 13.3-19.1 pmol/l) during the course with small differences in increase between the groups. Ingestion of a mixed meal reduced the fasting plasma secretin by about 40% during the course, while oral glucose reduced the plasma secretin to the concentrations found in the control experiment. The study shows that plasma secretin is increased when man is exposed to prolonged multifactorial stress. Additional food or sleep appears to have small influence on the fasting plasma secretin, but after giving a meal or oral glucose solution the plasma secretin decreases rapidly.

Regional differences in the lipolytic response of the subcutaneous fat depots to prolonged exercise and severe energy deficiency

After five days of almost continuous strenuous combat exercise and energy deficiency, 12 well-trained young men had a mean body fat loss of 2.7 kg and the average fat cell size was reduced from 0.34 microgram to 0.24 microgram. No significant changes were found in the total number of fat cells. For the group as a whole, the decrease in fat cell size was most pronounced in the gluteal subcutaneous region, followed by the abdominal region. No significant decrease in fat cell size was encountered in tissue samples from the femoral site. Before the course, and on the last day, the subjects accomplished a short-term bicycle exercise at 50% of the individual's VO2. On day 5, positive correlations were found between the fat cell weights estimated in the gluteal tissue samples and the pre-exercise free fatty acid (FFA) levels (r = 0.87, p less than 0.01), and also with the plasma free glycerol obtained five minutes after the bicycle exercise (r = 0.93, p less than 0.001). These correlations were not apparent in the control experiment performed before the course. Further, no such relationship was found between the plasma metabolites and the fat cell size of the other body sites investigated. This finding may indicate that gluteal fat deposits are more important for energy provision than abdominal and, especially, femoral deposits.

hPP and gastrin response to a liquid meal and oral glucose during prolonged severe exercise, caloric deficit, and sleep deprivation

Sixteen young healthy military cadets were subjected to prolonged severe exercise, caloric supply deficiency, and sleep deprivation during a 5-day ranger training course. Several cadets complained of gastric discomfort. The fasting and postprandial human pancreatic polypeptide (hPP) and gastrin levels induced by a liquid meal (no. = 9) and peroral glucose load (no. = 7) were measured during normal school activities (control) and on the third day during the course. The results showed that the fasting level of hhPP was significantly increased during the course. Both during meal and glucose stimulation the hPP level during the course was significantly higher at most registrations than during control conditions. The fasting level of gastrin was not changed. The maximal level of gastrin during meal stimulation was higher during the course than during the control period. Glucose loading, on the other hand, did not change the gastrin response. The integrated response of hPP and gastrin were not changed during the course either for the liquid meal or for the peroral glucose load.

Metabolic responses to bicycle exercise after several days of physical work and energy deficiency

The responses of plasma free fatty acids (FFA), free glycerol, beta-hydroxybutyrate (BUT) and glucose to bicycle exercise (corresponding to 50% of the maximal VO2) were investigated in 11 cadets of the Norwegian Military Academy, before a combat course (control experiment) and on the third and fifth day of such a course which involved nearly continuous intense military activities and pronounced energy deficiency. Pre-exercise levels of FFA, glycerol and BUT were greatly elevated on days 3 and 5 as compared with pre-exercise levels before the course. The increases in plasma FFA, glucose and BUT in response to bicycle exercise were much more pronounced on days 3 and 5 than before the course. The increases observed during (and before) the course were approximately in mmol/l: FFA 1.0 (0.3), glycerol 0.3 (0.08), BUT 0.6 (0.0). The day 5 responses were lower than those on day 3. The plasma glucose concentration appeared to decrease slightly after exercise on days 3 and 5. The results demonstrate that several days of strenuous work and pronounced energy deficiency do appreciably increase acute metabolic responses to exercise, and indicate that there is a very high FFA-utilization under such conditions.

Serum ferritin in young men during prolonged heavy physical exercise

The level of serum ferritin were investigated in 44 young men during strenuous ranger training courses lasting 4-5 d. These cadets were continuously subjected to heavy physical activities, almost without sleep and with a caloric deficit amounting to 29000-39000 kj per 24 h. Ferritin concentrations were consistently increased during the courses, and were still significantly elevated 2 d after the end of the courses. The increase of ferritin appeared to be correlated with decreased Hb values and increased total bilirubin. The results indicate that iron released from disintegrated erythrocytes probably causes increased ferritin synthesis in the reticuloendothelic cells and a subsequent release of ferritin in blood.

The effect of a high calory diet on hormonal changes in young men during prolonged physical strain and sleep deprivation

Major changes occur in the serum level of several hormones during 5 days of heavy and continuous physical activities, with less than a total of 2 h of sleep. The present investigation was designed to evaluate the importance of caloric deficiency, energy requirement being about 8,000-10,000 kcal/24 h. A comparison between well fed subjects and those with food deprivation revealed significantly higher levels of (T3) triiodothyronin, insulin and thyroid stimulating hormone (TSH) in the well-fed subjects, who also had lower levels of growth hormone (hGH) and cortisol, whereas no difference was found between the two groups for thyroxin (T4). Increased levels were found for T3 and T4 in both groups during the first day of activity, with a concomitant decrease in TSH and a subsequent decrease of T4 during the next 2 days. T3 decreased only in the low-calory group whereas increased levels were found in the iso-calory group throughout the course. The resting levels of insulin decreased during the course in the low-calory group whereas it increased in the iso-calory group. High levels were maintained throughout the course for hGH. Cortisol showed high levels just before the start of the course and then decreased from day 2 to day 4. No difference was found between the morning and evening levels for cortisol, indicating disappearance of the circadian rhythm. The present investigation has shown that energy deficiency during prolonged physical strain is responsible for the decreased serum levels of T3 and insulin and may contribute to the decrease in TSH and the increase in hGH and cortisol.

Altered hormonal response to short-term bicycle exercise in young men after prolonged physical strain, caloric deficit, and sleep deprivation

The hormonal response to a standardized bicycle exercise test was studied in 11 male cadets exposed to a course of 107 h of continuous activity with less than 2 h sleep. The subjects expended only about 8,600-11,000 kcal/24 h whereas their daily food intake contained only about 1,500 kcal. The exercise test was performed once 12 days before the course (control experiment) and on day 3 and day 5 during the course, always between 0700-0900 h. A two to six fold increase was seen in the resting levels of noradrenaline, adrenaline, dopamine, and growth hormone during the course whereas a decrease was observed for thyroxine, triiodothyronine, and prolactin. Cortisol increased on day 3 and then decreased to precourse levels on day 5. The response to the exercise test during the course for all catecholamines was a further increase above and proportional to the raisted resting levels. Growth hormone increased by about 6-8 microgram/l both before and during the course. During the exercise test, cortisol decreased before the course whereas it increased during the course. All plasma levels of cortisol were higher on day 3 than on day 5 and in the control experiment. The post-exercise insulin increase was reduced during the course corresponding to a reduction in blood glucose levels. Prolactin decreased during and after exercise in the control experiment, whereas on day 5 the opposite response was seen. No changes in the disappearance rate of different hormones were observed during the course. The present investigation has demonstrated that prolonged strain severely affects the resting plasma levels of different hormones as well as the endocrine response to a short-term physical exercise.

Patterns of peptides and protein-associated-peptide complexes in psychiatric disorders

Peptidic neurones may be considered as multisignal intergrators and transducers. When formation or release of peptide outstrips genetically determined breakdown capacity, overflow of peptides to the body fluids and urine may be expected. In this paper, pathological urinary chromatographic patterns of peptides are shown for genetic, functional and mixed disorders. Part symptoms of the disorders may be induced with the biologically isolated and purified peptides as well as with chemically synthesized peptides.

Hormonal changes in serum in young men during prolonged physical strain

The endocrine response to severe physical strain including lack of sleep has been investigated in army personnel during a combat course of 5 days' duration. The thyroxine (T4) concentration in serum increased during the first 24 h, and then declined at a rate corresponding to a halflife of 7.6 days and on day 6 had reached the lowest level, 55 ng/ml. Triiodothyronine (T3) displayed a similar pattern, although an increase during the first 24 h could not be demonstrated. Within 48 h after the course T4 had returned to normal, whereas the serum level of T3 was significantly below the level before the course (p less than 0.05). The serum level of TSH was suppressed during the course. The serum level of prolactin was significantly suppressed and growth hormone was markedly elevated during the course with a significant negative correlation (r=-0.6) between the two. In agreement with a previous report, there was a rapid and sustained suppression of the serum level of testosterone to a mean level of 1.1 ng/ml on day 5. Short periods of sleep (3--6 h) were shown to be effective in reversing the changes described in this paper, especially for growth hormone, prolactin, and testosterone.

Performance, mood, and clinical symptoms in men exposed to prolonged, severe physical work and sleep deprivation

There were 44 young men who participated in strenuous combat courses of 4 d (course I) or 5 d (course II), almost without sleep. They were tested and examined clinically each morning. Groups 1 and 2 had no organized sleep, whereas groups 3 and 4 got 3 and 6 h, respectively, in the middle of each course. Substantial impairment was observed in all tests, as well as clinical symptoms toward the end of the courses for groups 1 and 2. In the vigilance test, the reaction time task, the code test, and the profile of mood-state, significant impairment was observed even after 24 h. Complaints of symptoms came first. Disturbance of senses and behaviour appeared later. Group 4 had significantly better results than groups 1 and 2 in clinical symptoms and all tests, except the positive score in mood-state. Group 3 occupied an intermediate position. Corresponding results were obtained in the two separate courses. In the morning following the course, recovery after 4 h of sleep was less extensive for courses II than course I participants.