Outdoor physical activity is not associated with better mental health in a sample of predominantly Black people, but spending time in parks is.

Spending time outdoors may bolster mental health via relaxation and physical activity. Yet, most studies use self-report and involve majority White samples from higher income areas. Findings may not hold true using device-derived measurement, among minoritized participants, or in low-income neighborhoods.

Four recommendations to tackle the complex reality of transdisciplinary, natural experiment research.

Natural experiments are often used to study interventions in which randomization to control versus intervention conditions are impossible. Nature-based interventions (i.e.

The effects of contemporary redlining on the mental health of Black residents.

Understanding how structural racism, including institutionalized practices such as redlining, influence persistent inequities in health and neighborhood conditions is still emerging in urban health research. Such research often focuses on historical practices, giving the impression that such practices are a thing of the past. However, mortgage lending bias can be readily detected in contemporary datasets and is an active form of structural racism with implications for health and wellbeing.

C-reactive protein and telomerase reverse transcriptase (TERT) associate with chronic disease markers in a sample from low-income neighborhoods in Detroit, Michigan.

Racial and ethnic minorities in economically deprived inner cities experience high rates of chronic diseases compared to neighborhoods with higher socioeconomic status (SES). However, these economically deprived populations are understudied in terms of biomarkers associated with chronic disease risk which include C-reactive protein (CRP), telomerase reverse transcriptase (TERT), and glycosylated hemoglobin (A1C). We examined relationships between CRP and TERT and chronic disease indicators (body mass index [BMI] and A1C) in two low-income, predominantly African American (AA) neighborhoods in Detroit, Michigan.

A Scoping Review of the Health Benefits of Nature-Based Physical Activity.

The health benefits of physical activity and spending time in nature are well established. However, youths and adults in the United States are not participating in sufficient levels of physical activity and are not spending much time outdoors. Recently, the need for equitable access to nature for all populations has been receiving more public health attention, though a specific focus on nature-based physical activity has been limited.

Time Spent in Nature Is Associated with Increased Pro-Environmental Attitudes and Behaviors.

Urbanization, screen dependency, and the changing nature of childhood and parenting have led to increased time indoors, creating physical and emotional distancing from nature and time spent in natural environments. Substantial evidence from observational and intervention studies indicates that overall time spent in nature leads to increased perceived value for connectedness to nature and, subsequently, greater pro-environmental attitudes and behaviors (PEAB). This narrative review of the recent literature evaluates associations between time spent in nature with values ascribed to nature and nature connectedness, as well as PEAB.

Feelings of safety during daytime walking: associations with mental health, physical activity and cardiometabolic health in high vacancy, low-income neighborhoods in Detroit, Michigan.

Introduction: Individuals living in low-income neighborhoods have disproportionately high rates of obesity, Type-2 diabetes, and cardiometabolic conditions. Perceived safety in one's neighborhood may influence stress and physical activity, with cascading effects on cardiometabolic health.

Methods: In this study, we examined relationships among feelings of safety while walking during the day and mental health [perceived stress (PSS), depression score], moderate-to-vigorous physical activity (PA), Body Mass Index (BMI), and hemoglobin A1C (A1C) in low-income, high-vacancy neighborhoods in Detroit, Michigan.

The effect of green walking on heart rate variability: A pilot crossover study.

We investigated the effects of regular walking in green and suburban environments on heart rate variability (HRV) and blood pressure (BP) in middle-aged adults. Twenty-three adults participated in a non-randomized crossover experiment comprised of once-weekly 50-min moderate-intensity walking sessions. Separated by a two-week washout period, participants walked for three weeks in each of two treatment conditions (green and suburban) in a local arboretum and suburban sidewalks of Chaska, MN.

Walking Green: Developing an Evidence Base for Nature Prescriptions.

Although the health benefits of exercise and exposure to nature are well established, most evidence of their interaction comes from acute observations of single sessions of activity. However, documenting improved health outcomes requires ongoing interventions, measurement of multiple outcomes, and longitudinal analyses. We conducted a pilot study to guide the development of a protocol for future longitudinal studies that would assess multiple physiological and psychological outcomes.

Effects of freshwater blue spaces may be beneficial for mental health: A first, ecological study in the North American Great Lakes region.

Research linking green space and mental health abounds. It also appears that oceanic blue spaces may be salutogenic, benefitting mental health through their expansive viewscapes, and possibly auditory and olfactory stimuli. Yet, it is unknown whether the same is true for freshwater bodies.

Changes in Psychological and Cognitive Outcomes after Green versus Suburban Walking: A Pilot Crossover Study.

This study investigated the acute effects of repeated walking sessions within green and suburban environments on participants' psychological (anxiety and mood) and cognitive (directed-attention) outcomes. Twenty-three middle-aged adults (19 female) participated in a non-randomized crossover study comprised of once-weekly 50-min moderate-intensity walking sessions. Participants walked for three weeks in each of two treatment conditions: green and suburban, separated by a two-week washout period.

Accelerated Episodic Luteinizing Hormone Release Accompanies Blunted Progesterone Regulation in PCOS-like Female Rhesus Monkeys (Macaca Mulatta) Exposed to Testosterone during Early-to-Mid Gestation.

Background/aims: Ovarian theca cell hyperandrogenism in women with polycystic ovary syndrome (PCOS) is compounded by androgen receptor-mediated impairment of estradiol and progesterone negative feedback regulation of episodic luteinizing hormone (LH) release. The resultant LH hypersecretion, likely the product of accelerated episodic release of gonadotropin-releasing hormone (GnRH) from the median eminence of the hypothalamus, hyperstimulates ovarian theca cell steroidogenesis, enabling testosterone (T) and androstenedione excess. Prenatally androgenized (PA) female monkeys exposed to fetal male levels of T during early-to-mid gestation, when adult, demonstrate PCOS-like traits, including high T and LH levels.

Progesterone receptor A (PRA) and PRB-independent effects of progesterone on gonadotropin-releasing hormone release.

Progesterone's (P4) negative feedback actions in the female reproductive axis are exerted in part by suppression of hypothalamic GnRH release. Here we show that P4 can inhibit GnRH release by a mechanism independent of a nuclear P4 receptor (PR(A/B)). Injections of P4, but not vehicle, allopregnanolone, or dexamethasone, acutely suppressed LH levels in both wild-type and P4 receptor knockout ovariectomized mice; pituitary responsiveness to GnRH was retained during P4 treatment, indicating a hypothalamic action.

Effects of progesterone on male-mediated infant-directed aggression.

Many species that engage in parental behavior exhibit infanticide under certain circumstances. The neural signals regulating the transition from infant care giver to infant killer and back remain unclear. Previously we demonstrated that progesterone (P) and its receptor (PR) have inhibitory effects on parental behavior and increase infant-directed aggression in male mice.

Fasting-induced suppression of LH secretion does not require activation of ATP-sensitive potassium channels.

Reproductive hormone secretions are inhibited by fasting and restored by feeding. Metabolic signals mediating these effects include fluctuations in serum glucose, insulin, and leptin. Because ATP-sensitive potassium (K(ATP)) channels mediate glucose sensing and many actions of insulin and leptin in neurons, we assessed their role in suppressing LH secretion during food restriction.

Neuroendocrine consequences of androgen excess in female rodents.

Androgens exert significant organizational and activational effects on the nervous system and behavior. Despite the fact that female mammals generally produce low levels of androgens, relative to the male of the same species, increasing evidence suggests that androgens can exert profound effects on the normal physiology and behavior of females during fetal, neonatal, and adult stages of life. This review examines the effects of exposure to androgens at three stages of development--as an adult, during early postnatal life and as a fetus, on reproductive hormone secretions in female rats.

Vasopressin regulation of the proestrous luteinizing hormone surge in wild-type and Clock mutant mice.

In the female mouse, ovulation and estrous cyclicity are under both hormonal and circadian control. We have shown that mice with a mutation in the core circadian gene Clock have abnormal estrous cycles and do not have a luteinizing hormone (LH) surge on the afternoon of proestrus due to a defect at the hypothalamic level. In the present study, we tested the hypotheses that vasopressin (AVP) can act as a circadian signal to regulate the proestrous release of LH, and that this signal is deficient in the Clock mutant.

Photoperiodic regulation of compensatory testicular hypertrophy in hamsters.

In mammals, removal of one testis results in compensatory testicular hypertrophy (CTH) of the remaining gonad. Although CTH is ubiquitous among juveniles of many species, laboratory rats, laboratory mice, and humans unilaterally castrated in adulthood fail to display CTH. We documented CTH in pre- and postpubertally hemi-castrated Syrian and Siberian hamsters and tested whether day length affects CTH in juvenile and adult Siberian hamsters.

Fetal origins of developmental plasticity: animal models of induced life history variation.

The interaction of the genetic program with the environment shapes the development of an individual. Accumulating data from animal models indicate that prenatal and early-postnatal events (collectively called "early-life events") can initiate long-term changes in the expression of the genetic program which persist, or may only become apparent, much later in the individual's life. Researchers working with humans or animal models of human diseases often view the effects of early-life events through the lens of pathology, with a focus on whether the events increase the risk for a particular disease.

Circadian clock mutation disrupts estrous cyclicity and maintenance of pregnancy.

Classic experiments have shown that ovulation and estrous cyclicity are under circadian control and that surgical ablation of the suprachiasmatic nuclei (SCN) results in estrous acyclicity in rats. Here, we characterized reproductive function in the circadian Clock mutant mouse and found that the circadian Clock mutation both disrupts estrous cyclicity and interferes with the maintenance of pregnancy. Clock mutant females have extended, irregular estrous cycles, lack a coordinated luteinizing hormone (LH) surge on the day of proestrus, exhibit increased fetal reabsorption during pregnancy, and have a high rate of full-term pregnancy failure.

Chemosensory stimulation of luteinizing hormone secretion in male Siberian hamsters (Phodopus sungorus).

Male Siberian hamsters (Phodopus sungorus) housed in long days (LD), but not short days (SD) release luteinizing hormone (LH) when exposed to females. This study examined whether this response is specific to a female and identifies the source of a stimulus that induces LH release. Serum concentrations of LH, testosterone (T), follicle stimulating hormone (FSH), and cortisol were examined in all experiments.

Aging alters circadian and light-induced expression of clock genes in golden hamsters.

Aging alters numerous aspects of circadian biology, including the amplitude of rhythms generated by the suprachiasmatic nuclei (SCN) of the hypothalamus, the site of the central circadian pacemaker in mammals, and the response of the pacemaker to environmental stimuli such as light. Although previous studies have described molecular correlates of these behavioral changes, to date only 1 study in rats has attempted to determine if there are age-related changes in the expression of genes that comprise the circadian clock itself. We used in situ hybridization to examine the effects of age on the circadian pattern of expression of a subset of the genes that comprise the molecular machinery of the circadian clock in golden hamsters.

Progesterone receptors mediate male aggression toward infants.

Neuroendocrine mechanisms that mediate male aggression toward infants are poorly understood. Although testosterone is known to enhance aggression in other social contexts, evidence that it modulates aggression toward infants is equivocal. We have found that male progesterone receptor knockout (PRKO) mice exhibit no infanticidal behavior and little aggression toward young.

Differential regulation of luteinizing hormone and follicle-stimulating hormone in male siberian hamsters by exposure to females and photoperiod.

Siberian hamsters have decreased gonadotropin levels and testis size after short-day (SD) exposure. Upon transfer from short to long days, FSH and testis weight increase rapidly, whereas LH and T remain low for much longer. We investigated whether an additional environmental stimulus, specifically a female, could trigger an earlier release of LH and whether the response to the female was dependent on photoperiod.

Feeding melatonin enhances the phase shifting response to triazolam in both young and old golden hamsters.

Aging alters many aspects of circadian rhythmicity, including responsivity to phase-shifting stimuli and the amplitude of the rhythm of melatonin secretion. As melatonin is both an output from and an input to the circadian clock, we hypothesized that the decreased melatonin levels exhibited by old hamsters may adversely impact the circadian system as a whole. We enhanced the diurnal rhythm of melatonin by feeding melatonin to young and old hamsters.