Publications by authors named "Amy K Eppolito"

Neuroactive steroids are increasingly implicated in the development of depression and anxiety and have been suggested as possible treatments for these disorders. While neuroactive steroids, such as pregnanolone, act primarily at γ-aminobutyric acidA (GABAA) receptors, other mechanisms might contribute to their behavioral effects and could increase their clinical effectiveness, as compared with drugs acting exclusively at GABAA receptors (e.g.

View Article and Find Full Text PDF

When reinforcers of different magnitudes are concurrently available, choice is greater for a large reinforcer; that choice can be reduced by delaying its delivery, a phenomenon called delay discounting and represented graphically by a delay curve in which choice is plotted as a function of delay to the large reinforcer. Morphine, administered acutely, can alter responding for large, delayed reinforcers. In this study, the impact of morphine tolerance, dependence and withdrawal on choice of delayed reinforcers was examined in six pigeons responding to receive a small amount of food delivered immediately or a larger amount delivered immediately or after delays that increased within sessions.

View Article and Find Full Text PDF

Rationale: Positive γ-aminobutyric acid(A) (GABA(A)) modulators acting at different binding sites often produce similar behavioral effects; however, their effects are not identical. Actions of neuroactive steroids at other receptors, in addition to GABA(A) receptors, might account for some differences between neuroactive steroids and other positive modulators, like benzodiazepines.

Objective: Multiple mechanisms of other drugs (e.

View Article and Find Full Text PDF

Delay to delivery of a reinforcer can decrease responding for that reinforcer and increase responding for smaller reinforcers that are available concurrently and delivered without delay; acute administration of drugs can alter responding for large, delayed reinforcers, although the impact of chronic treatment on delay discounting is not well understood. In this experiment, the effects of repeated administration of the benzodiazepine flunitrazepam were studied in 6 pigeons responding on one key to receive food that was delivered immediately and on a second key to receive a larger amount of food that was delivered following delays which increased across a single session. Pigeons responded predominantly for the large reinforcer when there were no delays and when delays were short; however, as delays increased, responding for the large reinforcer decreased.

View Article and Find Full Text PDF

Chronic treatment with benzodiazepines, which positively modulate γ-aminobutyric acidA (GABAA) receptors, can lead to the development of tolerance. Similar effects might also occur during chronic treatment with positive modulators acting at other sites on GABAA receptors (e.g.

View Article and Find Full Text PDF

Animal models of prenatal nicotine exposure clearly indicate that nicotine is a neuroteratogen. Some of the persisting effects of prenatal nicotine exposure include low birth weight, behavioral changes and deficits in cognitive function, although few studies have looked for neurobehavioral and neurochemical effects that might persist throughout the lifespan. Pregnant rats were given continuous infusions of nicotine (0.

View Article and Find Full Text PDF

Humans often start smoking during adolescence. Recent results suggest that rodents may also be particularly vulnerable to nicotine dependence during adolescence. We examined the effect of chronic nicotine exposure on gene expression profiles during adolescence in female rats, who were dosed with nicotine (and control animals were dosed with saline) via subcutaneously implanted osmotic minipumps.

View Article and Find Full Text PDF

Research has shown that cigarette use during pregnancy can result in increased fetal mortality, sudden infant death syndrome, and behavioral and attentional disorders during childhood. Neurochemical and behavioral consequences of prenatal nicotine exposure have been well documented although few studies have examined long-term behavioral consequences that persist into adulthood. In this study, fifty-eight male and female Long-Evans rats were exposed to chronic nicotine prenatally and postnatally via subcutaneous infusions (0.

View Article and Find Full Text PDF

Sixty male and female Long-Evans hooded rats were administered 1, 2, or 5mg/kg methylphenidate (MPH) suspended in apple juice on postnatal day (P)15 or P40 using a novel, non-invasive oral administration technique. Plasma was collected 15 min after ingestion and analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS) to confirm appropriate concentrations. HPLC-MS plasma analysis showed levels comparable to previous gavage studies using MPH.

View Article and Find Full Text PDF

Adolescent nicotine exposure is associated with long-term use, and it has been suggested that this vulnerability to addiction may relate to lasting anxiogenic effects of the drug. However, few studies have addressed long-term effects of adolescent nicotine, and fewer yet have compared adolescent to adult exposure. Male and female Long-Evans rats continuously received nicotine bitartrate or sodium tartrate via osmotic mini-pumps over 15 days either during adolescence (p28-42) or adulthood (p85-99).

View Article and Find Full Text PDF

The objective of the current study was to examine how periadolescent nicotine exposure affects dendritic morphology of medium spiny neurons from the nucleus accumbens shell. Male Long-Evans hooded rats were chronically administered nicotine or saline for a period extending from postnatal day 22 (p22) to p69. Nicotine and saline administration was via subcutaneously implanted osmotic pumps.

View Article and Find Full Text PDF