Table 1.
Some effects in reproductive success by changes in clock genes genotype in mammals.
| Clock gene | Species | Effect | Reference |
|---|---|---|---|
| Gonads | |||
| Bmal 1−/− | Mouse | Ovarian size reduced | (8) |
| Bmal 1−/− | Mouse | Low testosterone and high luteinizing hormone in serum; reduction in esteroidogenic genes in testes, reduced sperm count. Infertility | (12, 13) |
| Clock | Human polymorphism | Semen volume reduction, low sperm motility, and idiopathic infertility. Alteration in serum levels of testosterone and FSH | (14, 15) |
| Cry1 | Mouse KD | Reduction of meiotic process and maturation in oocytes | (16) |
| Bmal1flx/flx | Mouse | Changes in phasic LH sensitivity of theca cells in ovary | (17) |
| Bmal1flx/flx | Mouse | Failure to mate with receptive females. Low secretion of FSH and GnRH. Tyrosine hydroxylase in brain decreased | (18) |
| Estrous and menstrual cycles | |||
| ClockΔ19 | Mouse | Higher proportion of irregular estrous cycles | (19–21) |
| Clock | Mouseclock/clock | Irregular estrous cyclicity and failure to have a coordinated LH surge on proestrus | (22) |
| Bmal 1−/− | Mouse KO | Changes in daily pattern of estrogen receptor β in tissues implicated in female reproductive functions | (23, 24) |
| Clock | Human polymorphism | Irregular menstrual cycles | (25) |
| Gestational/parturition | |||
| Per 1−/− and Per 2−/− | Mouse | Successful parturition reduced | (7) |
| Bmal 1−/− | Mouse | Lack of implantation and embryonic development. Impaired steroidogenesis, low progesterone levels and embryo implantation reduced. Alterations in delivery times | (8–10, 26) |
| Clock | Mouseclock/clock | Elevated rates of fetal reabsorption | (5) |
| Bmal 1 | Human polymorphism | Miscarriages increased | (27) |
| Postpartum success | |||
| Per 1−/− and Per 2−/− | Mouse KO | Number of pups weaned reduced | (7) |
| ClockΔ19 | Mouse | Postnatal mortality increased and low prolactin levels and reduced milk production | (19, 28) |