Two clinically tolerable methods of producing testicular hypothermia have been studied in dogs. Evaporative cooling produced a 3.7 degree fall and ice water a 9.7 degree fall in intratesticular temperatures. Scrotal skin blood flow (mls/100 gm/min) fell from 4.9 +/- 4.6 to 2.3 +/- 1.2 and 1.3 +/- .05 with the two techniques and was associated with increased vascular resistance. In contrast, no significant change was noted in testicular blood flow. These data show that testicular blood flow cannot be altered by clinically tolerable hypothermia.
Twelve anoestrous ewes maintained under natural photoperiod at 57 degrees N received an oral dose of 3 mg melatonin daily at 15:00 h from 1 May. Starting 41 days later and extending from 11 June until 5 September, six of the ewes were also infused continuously with 0.8 mg thyrotrophin-releasing hormone (TRH) day-1 via subcutaneous osmotic minipumps. The remaining six ewes acted as controls. Behavioural oestrus, ovulation rate and luteal function were determined by exposure to a vasectomized ram, laparoscopy and the measurement of progesterone in peripheral plasma, respectively. TRH infusion stimulated a sustained increase (P < 0.001) in plasma concentrations of thyroxine, tri-iodothyronine and prolactin (thyroxine: 158 +/- 9.3 and 65 +/- 7.7 nmol l-1 for TRH-infused and control ewes, respectively; tri-iodothyronine, 2.6 +/- 0.12 and 1.1 +/- 0.19 nmol l-1 and prolactin, 57 +/- 12 and 11 +/- 2 micrograms l-1). No ewes were in oestrus before TRH infusion and the mean number of behavioural oestrous cycles per ewe during the infusion period was 1.3 +/- 0.33 and 2.5 +/- 0.34 for TRH-infused and control ewes, respectively (P < 0.05). Corresponding mean intervals from 1 May to the onset of the first luteal phase (progesterone > 1 ng ml-1) were 88 +/- 8.9 and 79 +/- 3.5 days (not significant). TRH infusion had no effect on the mean numbers of corpora lutea (1.7 +/- 0.14 and 1.6 +/- 0.20 for TRH-infused and control ewes, respectively), but was associated with a lower mean incidence of normal luteal phases (1.5 +/- 0.43 versus 2.7 +/- 0.21, P = 0.052). Abnormalities in luteal function included delayed initial expression, extended ovarian cycles, suprabasal periovulatory progesterone concentrations and protracted periods of low progesterone secretion between successive ovarian cycles. Thus continuous TRH infusion suppressed plasma prolactin, doubled the circulating concentrations of thyroxine and tri-iodothyronine, and was associated with a wide range of abnormalities in ovarian function and endocrine status, the nature of which varied between ewes.
IntroductionSarcopenia is a progressive loss in muscle mass, strength and function, the adverse consequences of which are severe, affecting quality of life and placing an increasing burden on social and healthcare systems. Vitamin D status is known to be associated with markers of sarcopenia, namely muscle mass, strength and function. Also, resistance exercise training (RET) is currently the only proven intervention to treat sarcopenia. However, very little data exist on the influence of combining the two interventions of vitamin D supplementation and resistance exercise training, although a recent systematic review provides tentative support for the current study’s hypothesis that the combined intervention may further improve musculoskeletal function above exercise training alone. The aim of the present study is to determine whether vitamin D3supplementation is any more effective in improving musculoskeletal function when combined with RET compared with exercise training alone in older adults.Methods and analysisThis double-blinded randomised placebo-controlled trial will recruit a target of 127 eligible men and women aged ≥65 years living independently or in sheltered housing within the Birmingham area to two groups: (1) 6 months RET and placebo or (2) 6 months RET and 800 IU/d vitamin D3. Measures of muscle power (Nottingham Power Rig), body composition (dual energy X-ray absorptiometry), muscle function (short physical performance battery, timed up and go), falls and fractures as events will be assessed. Assessments will take place at baseline and postintervention, with intermittent monitoring of bone turnover, calcium and vitamin D. The primary outcome will be lower limb extensor power output. Analyses of within-group changes and between-group differences in outcome measures are planned.Ethics and disseminationThe EXVITD study has ethical approval granted by the Black Country National Health Service Research Ethics Committee (14/WM/1220). Results of this trial will be submitted for publication in peer-reviewed journals and presented at conferences. The study is being conducted according to the principles of the Declaration of Helsinki.Trial registration numberNCT02467153; Post-results.
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