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

Abstract

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.

Maternal exposure to first‐trimester sunshine is associated with increased birth weight in human infants

“…It has been argued, for example, that increased exposure to sunshine during the first trimester of gestation may inhibit maternal melatonin production and stimulate the release of growth hormone (GH). Although high levels of melatonin are typically associated with high levels of GH (Laartz, Losee-Olson, Ge, & Turek, 1994;Zeman, Buyse, Lamosová, Herichová, & Decuypere, 1999), there is some evidence in both deer (Webster, Corson, Littlejohn, Stuart, & Suttie, 1998) and humans (Bellastella et al, 1994) for an inverse relation between melatonin and GH production. From this perspective, greater exposure to light during the first trimester of gestation may increase GH levels by inhibiting melatonin production.…”

Effect of Light Perception on Menarche in Blind Women

“…16 These findings are consistent with reports by Bellastella and Leger, who reported that blind people with varying degrees of light perception are shorter in stature and have a lower BMI than sighted controls. 2,3,17 The increased current BMI in NPL women does not account for the earlier menarche observed in this group, as could be hypothesized, 18 as their weight and BMI were significantly lower than LP women at age 18. Consistent with prior reports, we found no differences between LP and NPL women in age at natural menopause, which occurred around age 50.…”

“…The blind population has been shown to differ from the sighted population in that blind women are reportedly shorter in stature and have a lower BMI. 2,3 Further, menarche in blind women has been reported to be both earlier and the same as in sighted women. 4−6 Women with no perception of light (NPL) compared to women with light perception (LP) have been reported to have no differences in menopause or fertility.…”

Endocrine Secretions under Abnormal Light-Dark Cycles and in the Blind

“…Blindness has been shown to impair the growth of prepubertal [39] and the final stature of adult [40] institutionalized subjects. In this connection a negative influence of blindness on GH secretion has been described both in animals and in man.…”

“…A possible inhibiting action of MT on GH secretion, as demonstrated in animals [41], can be supposed also in man taking into account the high levels of MT in blind subjects [22, 23, 24, 25], even if exogenous administration of MT in man has been shown either to suppress [45, 46] or increase [47] GH secretion. However, since blind people show normal insulin-like growth factor I (IGF-I) levels, blindness could influence negatively the growth through complex mechanisms which do not involve only GH and IGF-I axis [40]. …”