Blindness influences the growth of institutionalized prepubertal subjects

Chrono-Endocrinology in Clinical Practice: A Journey from Pathophysiological to Therapeutic Aspects

This review was aimed at collecting the knowledge on the pathophysiological and clinical aspects of endocrine rhythms and their implications in clinical practice, derived from the published literature and from some personal experiences on this topic. We chose to review, according to the PRISMA guidelines, the results of original and observational studies, reviews, meta-analyses and case reports published up to March 2024. Thus, after summarizing the general aspects of biological rhythms, we will describe the characteristics of several endocrine rhythms and the consequences of their disruption, paying particular attention to the implications in clinical practice. Rhythmic endocrine secretions, like other physiological rhythms, are genetically determined and regulated by a central hypothalamic CLOCK located in the suprachiasmatic nucleus, which links the timing of the rhythms to independent clocks, in a hierarchical organization for the regulation of physiology and behavior. However, some environmental factors, such as daily cycles of light/darkness, sleep/wake, and timing of food intake, may influence the rhythm characteristics. Endocrine rhythms are involved in important physiological processes and their disruption may cause several disorders and also cancer. Thus, it is very important to prevent disruptions of endocrine rhythms and to restore a previously altered rhythm by an early corrective chronotherapy.

Endocrine rhythms and sport: it is time to take time into account

BACKGROUND

Studies of time-related biological phenomena have contributed to establishing a new scientific discipline, the chronobiology, which considers biological phenomena in relation to time. Sports activity profoundly affects the temporal organization of the organism and endocrine rhythms play a key role in the chronoorganization of individuals and are particularly important for correct physical activity. Correctly reading rhythmic hormonal variations of the human organism opens new horizons to sports medicine.

OBJECTIVE

This review is aimed at clarifying the relationship between endocrine rhythms and sports activities on the basis of the latest data in the literature.

METHOD

Data acquisition was obtained from three databases (PubMed, Scopus and SPORTDiscus), paying particular attention to reviews, meta-analysis, original and observational studies on this issue.

RESULTS

After the description of the general characteristics and parameters of biological rhythms, the main endocrine rhythms will be described, highlighting in particular the interrelationships with sports activity and focusing on the factors which can affect negatively their characteristics and consequently the psychophysical performances of the athletes.

CONCLUSION

Knowledge of this issue may allow establishing the best form of competitive or amateur activity, through the collaboration of an informed athlete and a sports physician attentive to biological rhythms. By taking into account that alteration of physiological rhythmic temporal organization can favour the onset of important diseases, including cancer, this will lead to the expected performances without impairing the correct chronoorganization of the athlete.

Twenty-four hour melatonin pattern in acromegaly: effect of acute octreotide administration

We investigated the melatonin (MT) circadian rhythm before and after somatostatin (octreotide) acute administration in ten subjects (4 M, 6 F. 23-52 yr old) with active acromegaly due to pituitary microadenoma. Blood samples were drawn every 2 hours over a 48-h span; after 24-h basal blood collection, octreotide (Sandostatin, Sandoz) 100 micrograms sc/8 h was administered. As control, 7 healthy adult subjects (3M, 4F; 26-50 yr old) were studied in basal condition over a 24-h span. Plasma MT and GH levels were measured by RIA in each sample, IGF-1 levels were measured by immunoradiometric assay in basal and after octreotide morning samples. The comparisons were made by Mann-U-Withney and Wilcoxon test as appropriate; the existence of a MT circadian rhythm was validated by cosinor analysis; GH and MT values were correlated by Pearson's correlation coefficient. All of 7 control subjects and 2 of 10 acromegalics had significant 24-h MT rhythm. The area under curve (AUC), mesor and amplitude of the MT rhythms in acromegalics were significantly lower than in the controls (p < 0.001, 0.002 and 0.0006, respectively), with an earlier acrophase (median value: 22:14 vs 02:08 h of controls). Basal plasma IGF-1 levels and circadian GH concentrations were significantly increased in acromegalics in comparison with the control group. Octreotide administration significantly reduced GH, restoring a circadian MT rhythm in 5 of 10 acromegalics, with MT mean mesor and AUC not different from controls. Mean amplitude still remained lower than controls (p < 0.0006), with an earlier acrophase (median 00:01 h). No significant correlation was found between individual GH and MT levels. Our data indicate a reduction of MT circadian secretion in acromegaly, due especially to a blunted nocturnal increase with earlier MT peak; moreover, acute octreotide administration increase MT levels without modifying amplitude and phase of night-time secretion significantly. These findings suggest a negative interrelationship between GH and MT secretions or a facilitatory influence of somatostatin on daytime MT release only. This partial recovery of pineal secretion after octreotide in acromegalics could be a clinically significant contribution to improve their quality of life, considering that MT is involved in the regulation of several important functions.

Normal plasma insulin-like growth factor I levels and impaired final stature in adult blind subjects

The aim of this study was to determine if changes in IGF-1 levels and in final stature occur in blind adult subjects. Eighteen subjects (4 females and 14 males) with total blindness (Group 1) and 26 subjects (5 females and 21 males) with only light perception (Group 2), living at an Institute for blind adult subjects in Naples, Italy, were studied. Their height and weight were compared to British standards. Plasma morning IGF-1 levels, measured by IRMA method were compared to those of 18 normal controls (6 females and 12 males) matched for age and weight. A high prevalence of short stature was demonstrated especially in Group 1 (p = 0.00005 by chi-square for trend test) but was also present in Group 2 (p = 0.02). No alterations in weight distribution were observed in both groups. Basal IGF-I levels in both Group 1 and Group 2 were similar to those of controls: IGF-1 (M +/- SE), 30.9 +/- 2.9 nmol/L and 37.9 +/- 2.7 nmol/L, respectively, vs 33.3 +/- 2.9 nmol/L, NS. High prevalence of final short stature in both groups confirms a negative influence of total or partial blindness on growth. These complex mechanisms appear to involve more than alterations in GH and IGF-I secretion.