John T. Clark

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Observations that a pancreatic polypeptide-like substance, possibly neuropeptide Y, is present in hypothalamic areas and may coexist with catecholamines prompted evaluation of its role in controlling feeding behavior. Intracerebroventricular administration of 2 or 10 micrograms of human pancreatic polypeptide to ovariectomized rats pretreated with estradiol(More)
Clonidine, a commonly used antihypertensive agent believed to act by stimulation of central alpha-adrenoceptors, produced a dose-related suppression of ejaculatory behavior in sexually vigorous male rats throughout the range of treatment (0.0125-0.5 mg/kg). Treatment with 0.25 mg/kg virtually eliminated ejaculatory behavior, without altering the number of(More)
Methamphetamine (METH) is a highly addictive and neurotoxic psychostimulant. Its use in humans is often associated with neurocognitive impairment. Whether this is due to long-term deficits in short-term memory and/or hippocampal plasticity remains unclear. Recently, we reported that METH increases baseline synaptic transmission and reduces LTP in an ex vivo(More)
Sheared flagella from Giardia lamblia were freed from cytoskeleton fragments and other cell contaminants by centrifuging in a density gradient. The purified organelles contain many polypeptides, including a set of low-molecular-weight antigens [apparent molecular weights (MWs)=31, 32, 34, 35 and 37 kD] in the same size range as the ∼ 30 kD structural(More)
Yohimbine hydrochloride, an alpha 2-adrenoceptor antagonist, increased sexual motivation in male rats as evidenced by increased mounting performance in mating tests conducted after genital anesthetization, increased percentage of male rats ejaculating in their first heterosexual encounter, and induction of copulatory behavior in sexually inactive male rats.(More)
The effects of neuropeptide Y (NPY), a tyrosine-rich peptide found in the rat brain, on feeding and sexual behavior were studied in male and female rats. Intraventricular (ivt) injections of NPY during the final hours of the light period induced feeding in a dose-related manner. While the lowest dose tested (0.02 nM) was without effect, higher doses (0.12,(More)
Neuropeptide Y (NPY) has been implicated in the control of ingestive, cardiovascular, and reproductive function. Blood pressure and sexual function were examined in Long-Evans rats receiving 6% ethanol-containing or calorically matched liquid diets, or rat chow ad lib. After 12 weeks of exposure, rats were sacrificed and plasma hormone levels and NPY(More)
Administration of RDS-127 (3.0 mg/kg) induced seminal emission within three minutes of IP injection and suppressed the display of penile reflexes in intact and spinally transected rats. In Experiment 1, RDS-127 was administered to intact, sexually experienced rats in a protocol previously demonstrated to selectively lower the ejaculatory threshold of(More)
Yohimbine HCL (2 mg/kg, 20 min prior to testing) administration was followed by significant decreases in the latencies to initial mount, intromission and ejaculation in castrated male rats bearing 2 mm testosterone-containing Silastic capsules 51 days after castration. Further, yohimbine stimulated copulatory activity in castrated, nonhormone-treated male(More)
OBJECTIVE To examine whether diet intervention can promote increased vegetable and fruit intake, as reflected in increased plasma carotenoid and decreased plasma total homocysteine concentrations, in premenopausal women with cervical intraepithelial neoplasia, a precancerous condition. DESIGN Randomized controlled diet intervention study. SUBJECTS(More)