Neonatal resuscitation

Insulin sensitivity, leptin, adiponectin, resistin, and testosterone in adult male and female rats after maternal-neonatal separation and environmental stress

Care of premature infants often requires parental and caregiver separation, particularly during hypoxic and hypothermic episodes. We have established a neonatal rat model of human prematurity involving maternal-neonatal separation and hypoxia with spontaneous hypothermia prevented by external heat. Adults previously exposed to these neonatal stressors show a sex difference in the insulin and glucose response to arginine stimulation suggesting a state of insulin resistance. The current study used this cohort of adult rats to evaluate insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR)], plasma adipokines (reflecting insulin resistance states), and testosterone. The major findings were that daily maternal-neonatal separation led to an increase in body weight and HOMA-IR in adult male and female rats and increased plasma leptin in adult male rats only; neither prior neonatal hypoxia (without or with body temperature control) nor neonatal hypothermia altered subsequent adult HOMA-IR or plasma adiponectin. Adult male-female differences in plasma leptin were lost with prior exposure to neonatal hypoxia or hypothermia; male-female differences in resistin were lost in the adults that were exposed to hypoxia and spontaneous hypothermia as neonates. Exposure of neonates to daily hypoxia without spontaneous hypothermia led to a decrease in plasma testosterone in adult male rats. We conclude that neonatal stressors result in subsequent adult sex-dependent increases in insulin resistance and adipokines and that our rat model of prematurity with hypoxia without hypothermia alters adult testosterone dynamics.

Sex differences in adult rat insulin and glucose responses to arginine: programming effects of neonatal separation, hypoxia, and hypothermia

Acute neonatal hypoxia, a common stressor, causes a spontaneous decrease in body temperature which may be protective. There is consensus that hypothermia should be prevented during acute hypoxia in the human neonate; however, this may be an additional stress with negative consequences. We hypothesize that maintaining body temperature during hypoxia in the first week of postnatal life alters the subsequent insulin, glucose, and glucagon secretion in adult rats. Rat pups were separated from their dam daily from postnatal days (PD) 2-6 for the following 90 min experimental treatments: (1) normoxic separation (control), (2) hypoxia (8% O2) allowing spontaneous hypothermia, (3) normoxic hypothermia with external cold, and (4) exposure to 8% O2 while maintaining body temperature using external heat. An additional normoxic non-separated control group was performed to determine if separation per se changed the adult phenotype. Plasma insulin, glucose, and glucagon responses to arginine stimulation were evaluated from PD105 to PD133. Maternal separation (compared to non-separated neonates) had more pronounced effects on the adult response to arginine compared to the hypoxic, hypothermic, and hypoxic-isothermic neonatal treatments. Adult males exposed to neonatal maternal separation had augmented insulin and glucose responses to arginine compared to unseparated controls. Additionally, neonatal treatment had a significant effect on body weight gain; adults exposed to neonatal maternal separation were significantly heavier. Female adults had significantly smaller insulin and glucose responses to arginine regardless of neonatal treatment. Neonatal maternal separation during the first week of life significantly altered adult beta-cell function in a sexually dimorphic manner.

Effects of body temperature maintenance on glucose, insulin, and corticosterone responses to acute hypoxia in the neonatal rat

One of the biggest challenges of premature birth is acute hypoxia. Hypothermia during acute hypoxic periods may be beneficial. We hypothesized that prevention of hypothermia during neonatal hypoxia disrupts glucose homeostasis and places additional metabolic challenges on the neonate. Pups at PD2 and PD8 were exposed to 8% O2 for 3 h, during which they were allowed to either spontaneously cool or were kept isothermic. There was also a time control group that was subjected to normoxia and kept isothermic. Plasma glucose, insulin, C-peptide, corticosterone, and catecholamines were measured from samples collected at baseline, 1 h, 2 h, and 3 h. In postnatal day 2 (PD2) rats, hypoxia alone resulted in no change in plasma glucose by 1 h, an increase by 2 h, and a subsequent decrease below baseline values by 3 h. Hypoxia with isothermia in PD2 rats elicited a large increase in plasma insulin at 1 h. In PD8 rats, hypoxia with isothermia resulted in an initial increase in plasma glucose, but by 3 h, glucose had decreased significantly to below baseline levels. Hypoxia with and without isothermia elicited an increase in plasma corticosterone at both ages and an increase in plasma epinephrine in PD8 rats. We conclude that the insulin response to hypoxia in PD8 rats is associated with an increase in glucose similar to an adult; however, insulin responses to hypoxia in PD2 rats were driven by something other than glucose. Prevention of hypothermia during hypoxia further disrupts glucose homeostasis and increases metabolic challenges.

Neurocritical care for neonates

OPINION STATEMENT

Neurocritical care is an emerging subspecialty that combines expertise in neurology, critical care medicine, neuroradiology, and neurosurgery. Increasing evidence from the adult literature suggests that specialized neurocritical care can lead to improved outcomes following acute brain injury. Critically ill neonates with neurologic conditions may also benefit from specialized neurocritical care. Adherence to guidelines and managing patients in intensive care nurseries with dedicated, multidisciplinary neurocritical care personnel may optimize outcomes. This goal may be achieved by more quickly recognizing neurologic impairment, preventing secondary brain injury by maintaining basic physiologic functions, and rapidly implementing therapies. Nurseries that care for neonates with suspected acute brain injury should be prepared to adequately support multiorgan involvement, monitor the brain to detect seizures, evaluate for brain injury using MRI, and follow development through school age.