Pituitary-gonadal hormones during prolonged residency in Antarctica

Abstract

Plasma luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin (PRL) and testosterone levels were measured in nine eugonadal men in New Delhi and during the 1st week of different months of their stay at Dakshin Gangotri in Antarctica. During their 12-month stay in Antarctica, they were exposed to a severely cold climate, long polar nights and polar days, high wind velocity, increased amounts of solar and ultraviolet radiation and geomagnetism, as well as physical and social isolation. Plasma testosterone tended to increase in March, but a significant increase (P < 0.05) was not seen until April. The mean testosterone levels in May, June, September and November were also significantly higher than the March or New Delhi values. The absolute values of LH, FSH and PRL did not show any month-to-month changes in Antarctica. However, when the hormone levels were expressed as a percentage of the individual annual Antarctic mean, significant differences as a percentage of the individual annual Antarctic mean, significant differences were observed. The testosterone peak in April, May and June was associated with an increase in LH. The nadirs of testosterone, LH, FSH and PRL were seen in either July or August. FSH showed the highest values in March, whereas the highest PRL values were seen in November. These observations suggest the presence of circannual variations in gonadotropin, PRL and LH in Antarctica which are independent of polar days and polar nights. It appears that factors other than the duration of daylight might be involved in regulating these changes. The significance of maintenance of testosterone levels in the supra-physiological range in Antarctica remains unknown but may be important in acclimatization/habituation to the extreme polar cold by increasing basal metabolic rate, protein synthesis and erythropoiesis.

Effect of warm‐rearing and heat acclimation on pituitary‐gonadal axis in male rats

“…In those males, like in other heat-exposed groups, plasma corticosterone concentration (38-43 ng ⁄ mL) was within the normal range for male rats (Retana-Marquez et al, 2003). Stress conditions rather lowered the plasma concentration of testosterone, LH and FSH (Ruisseau et al, 1978;Retana-Marquez et al, 2003), but during prolonged stay in Antarctica, Indian men had increased plasma concentration of testosterone, LH, FSH and PRL (Sawhney et al, 1998). The latter results are similar to that observed in our DA male rats.…”

“…, 1978; Retana‐Marquez et al. , 2003), but during prolonged stay in Antarctica, Indian men had increased plasma concentration of testosterone, LH, FSH and PRL (Sawhney et al. , 1998).…”

Seasonal Changes of Serum Gonadotropins and Testosterone in Men Revealed by a Large Data Set of Real-World Observations Over Nine Years

“…In the literature, 15 clinical trials investigated testosterone seasonality ( Table 3). Ten studies detected testosterone fluctuations along the year (66.7%) (28)(29)(30)(35)(36)(37)(38)(39)(40)(41), with an annual pattern of testosterone secretion highlighted in most cases, and a bi-annual pattern detected only in 3 out of 10 studies (Table 3), whereas 5 did not (27,(31)(32)(33)(34). Almost all previous studies evaluated small groups of men and only 3 studies considered more than one thousand subjects.…”

Changes in sleep patterns during prolonged stays in Antarctica

“…Adaptation of overwintering members during prolonged stays in Antarctica is manifested by changes in various physiological variables (Broadway and Arendt 1988;Broadway et al 1987;Kennaway and Van Dorp 1991;Sawhney et al 1995Sawhney et al , 1998Malhotra et al 1998;Yoneyama et al 1999) along with changes in sleep patterns (Joern et al 1970;Natani et al 1970;Paterson 1975;Palinkas et al 2000). Sleep studies carried out in previous Antarctic expeditions yielded two sets of observations.…”