Biology Reference
In-Depth Information
permit a better understanding of the physiological mechanisms responsible for puber-
tal timing and will help to decipher the pathophysiological basis for pubertal alterations
in humans and wildlife species.
1. PUBERTY IS A KEY DEVELOPMENTAL TRANSITION
Puberty is an essential event in the lifespan of any individual, in which
sexual and somaticmaturation is achieved, and reproductive capacity attained
(
Parent et al., 2003
). In addition, important growth, behavioral, and psycho-
logical changes occur at puberty, thus allowing the acquisition of a complete
adult phenotype. Because of its substantial importance as a life-changing
phenomenon, the physiology of puberty and the pathophysiology of its alter-
ations have been subjected to thorough analyses; yet, whilemuch progress has
taken place in the field in the last decades, our understanding of the molecular
and neurohormonal basis of mammalian puberty is still incomplete. This is
partially due to the multifaceted and transitional nature of puberty, which
requires the concerted action of different homeostatic systems that become
precisely activated (or inactivated) during pubertal maturation.
Indeed, rather than a specific time-point in postnatal development, puberty
is the culmination of a complex series of maturational events that start
in utero
and progress throughout early postnatal, infantile, and juvenile ages. These
result in a diversity of phenotypic indices, whose timing is shaped by the
dynamic interplay between our gene load and the environment. Thus, while
the age of puberty is subjected to considerable genetic determination
(
Gajdos, Henderson, Hirschhorn, & Palmert, 2010
), environmental cues
may account for a substantial variation in the age of puberty evenwithinhomo-
geneous populations (
Parent et al., 2003
). Accordingly, puberty has been reg-
arded as a biological
sensor
and the trends for changes in the timing of puberty, as
apparently detected in recent years in different wildlife species and human
populations (see below), are considered a potential biomarker for the suspected
deterioration of the environmental influences on reproductive health.
Although the age limits for normal human puberty are somewhat ample
and dependent on different ethnic and geographical factors (
Parent et al.,
2003
), several epidemiological studies published in recent years have docu-
mented a trend for an earlier initiation of puberty, as estimated by the begin-
ning of breast development (namely, thelarche) (
Aksglaede, Juul, Olsen, &
Sorensen, 2009; Aksglaede, Sorensen, Petersen, Skakkebaek, & Juul, 2009
).
