Megan M. Mahoney

Learn More
While much is known about the mechanisms that underlie sleep and circadian rhythms, the investigation into sex differences and gonadal steroid modulation of sleep and biological rhythms is in its infancy. There is a growing recognition of sex disparities in sleep and rhythm disorders. Understanding how neuroendocrine mediators and sex differences influence(More)
In a laboratory population of unstriped Nile grass rats, Arvicanthis niloticus, individuals with two distinctly different patterns of wheel-running exist. One is diurnal and the other is relatively nocturnal. In the first experiment, the authors found that these patterns are strongly influenced by parentage and by sex. Specifically, offspring of two(More)
UNLABELLED The development of adult circadian function, particularly sexual dimorphism of function, has been well studied only in rapidly developed rodents. In such species development is complete by weaning. Data from adolescent humans suggest that significant development occurs during the pubertal period. We hypothesized that a more slowly developing(More)
Diurnal and nocturnal animals differ with respect to the timing of a host of behavioral and physiological events including those associated with neuroendocrine functions, but the neural bases of these differences are poorly understood. In nocturnal species, rhythms in tyrosine hydroxylase-containing (TH+) neurons in the hypothalamus appear to be responsible(More)
Circadian rhythms and "clock gene" expression are involved in successful reproductive cycles, mating, and pregnancy. Alterations or disruptions of biological rhythms, as commonly occurs in shift work, jet lag, sleep deprivation, or clock gene knock out models, are linked to significant disruptions in reproductive function. These impairments include altered(More)
The underlying neural causes of the differences between nocturnal and diurnal animals with respect to their patterns of rhythmicity have not yet been identified. These differences could be due to differences in some subpopulation of neurons within the suprachiasmatic nucleus (SCN) or to differences in responsiveness to signals emanating from the SCN. The(More)
This article describes the phase response curve (PRC), the effect of light on Fos immunoreactivity (Fos-IR) in the suprachiasmatic nucleus (SCN), and the effect of SCN lesions on circadian rhythms in the murid rodent, Arvicanthis niloticus. In this species, all individuals are diurnal when housed without a running wheel, but running in a wheel induces a(More)
The slowly maturing, long-lived rodent Octodon degus (degu) provides a unique opportunity to examine the development of the circadian system during adolescence. These studies characterize entrained and free-running activity rhythms in gonadally intact and prepubertally gonadectomized male and female degus across the first year of life to clarify the impact(More)
The suprachiasmatic nucleus is the site of the primary circadian pacemaker in mammals. The lower sub paraventricular zone that is dorsal to and receives input from the suprachiasmatic nucleus may also play a role in the regulation of circadian rhythms. Calbindin has been described in the suprachiasmatic nucleus of some mammals, and may be important in the(More)
Daily rhythms in the timing of the preovulatory surge and the display of reproductive behavior are reversed in diurnal and nocturnal rodents, but little is known about the neural mechanisms underlying these differences. We examined this issue by comparing a diurnal murid rodent, Arvicanthis niloticus (the grass rat), to a nocturnal one, Rattus norvegicus(More)