Hypoxia
alters testis development in neonatal rats
Jian-Xiang
Liu & Ji-Zeng Du
Division of Neurobiology and Physiology, College of Life Sciences,
Zhejiang University, Yuquan Campus, Hangzhou 310027,
People's Republic of CHINA.
Keywords:
hypoxia; testis; postnatal development; testosterone; mitochondria
Abstract
OBJECTIVE:
To investigate the effects of continued hypoxia on postnatal
development of the rat testis.
DESIGN:
Wistar rats were exposed to simulated hypoxia from birth to
postnatal day (PND) 45. Testosterone (T) in the plasma and
the testis was measured in rats at PND 3, 7, 14, 21, 28, 35
and 45 respectively. Testis histology and cellular ultrastructure
were studied.
RESULTS:
a) Hypoxia induced a significant arrest of testes weight gain
after PND 28; b) T release was significantly attenuated after
PND 21; c) Alterations in histology and cellular ultrastructure
were found in the testis, showing the swelling of testis interstitium
and the enlargement of mitochondria in Leydig cells.
CONCLUSION:
Postnatal hypoxia stress alters testis development both in
terms of function and structure, especially at the critical
age of gonadal development.
ABBREVIATIONS
GH - Growth hormone
HPA - axis Hypothalamic-pituitary-adrenal axis
PND - Postnatal day
RIA - Radioimmunoassay
SHRP - Stress hyporesponsive period
T - Testosterone
Introduction
At
high altitude, hypoxia is the critical stress factor influencing
reproductive health. During the past decades, a number of studies
have dealt with growth, development and reproduction under hypoxic
conditions [1–8]. High altitude hypoxia delays onset of puberty
in female rats [4–6]. In adult male rodents, hypoxia inhibits
gonadotropins synthesis and release [9,10]. Chronic hypoxia
induces a decrease in plasma testosterone (T) level [11], without
changing T biosynthesis by the testis in vitro [12]. Moreover,
chronic hypoxia arrests spermatogenesis in rats [13] and monkeys
[14]. However, studies on the effects of hypoxia on testis development
are few. With the increasing human activities at the Qinghai-Tibet
Plateau in China, there is a growing concern about the reproductive
development and performance at high altitude. The current study
was designed to investigate the effects of hypoxia on development
of the rat testis from the neonatal to reproductively mature
ages.
Material and methods
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