Does increased sunlight exposure work as a strategy to improve vitamin D status in the elderly: a cluster randomised controlled trial.

SUMMARY: Sunlight exposure by improving vitamin D status could be a simple public health strategy in reducing falls among frail elder people. In a randomised controlled trial, adherence to sunlight exposure was low (median adherence, 26%) and no effect of increased UV exposure on falls risk was observed (incidence rate ratio (IRR) 1.06, P = 0.73). INTRODUCTION: This study aimed to determine whether increased sunlight exposure was effective to improve vitamin D status and reduce falls in the elderly. METHODS: In a cluster randomised controlled trial (NCT00322166 at ClinicalTrials.gov), 602 residents aged 70 or more (mean age, 86.4 years; 71% female) were recruited from 51 aged care facilities in Northern Sydney, Australia. Participants were randomised by facility to receive either increased sunlight exposure (additional 30-40 min/day in the early morning) with (UV+) or without (UV) calcium supplementation (600 mg/day) or neither (control) for a year. The co-primary endpoints were change in serum 25 hydroxy vitamin D (25OHD) and falls incidence after 12 months. RESULTS: Adherence to sunlight exposure was low (median adherence, 26%; IQR, 7%-45%). Serum 25OHD levels were low at baseline (median, 32.9 nmol/L) and increased only slightly depending on the number of sunlight sessions attended over 12 months (P = 0.04). During the study, 327 falls occurred in 111 (54%) subjects in the control group, 326 falls in 111 (58%) subjects in the UV only group and 335 falls in 108 (52%) subjects in the UV+ group. By intention-to-treat analysis, there was no significant effect of increased UV exposure on falls risk (IRR, 1.06; 95% CI, 0.76-1.48; P = 0.73). However, in 66 participants who attended ≥130 sessions per year (adherence, ≥50% of 260 sessions-five per week), falls were significantly reduced (IRR, 0.52; 95% CI, 0.31-0.88; P = 0.01) compared with the control group. CONCLUSIONS: Increased sunlight exposure did not reduce vitamin D deficiency or falls risk in frail older people. This public health strategy was not effective most likely due to poor adherence to the intervention.

Influence of gonadectomy and testosterone supplementation on the postnatal development of the vasopressin and oxytocin-containing nucleus of the pig hypothalamus.

We have studied the effects of gonadectomy and testoterone supplementation on the development of the vasopressin- and oxytocin-containing nucleus (VON) of the pig hypothalamus that shows a decrease in neuron number during the first weeks postnatally, followed by an increase during puberty. Neonatal gonadectomy caused a 2.5-fold increase in VON volume and neuron number in males and 3-fold in females at the age of 16 weeks, the onset of puberty. However, the difference between gonadectomized and nongonadectomized animals disappeared after puberty (38 weeks). Testosterone replacement from 16 weeks onwards induced a decrease in neuron number and volume of the VON. The present study indicates that the development of the VON is influenced by gonadal steroids although it seems improbable that these hormones affect the VON directly.