High vegetable and fruit diet intervention in premenopausal women with cervical intraepithelial neoplasia

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

Fifty-three free-living premenopausal women who had been diagnosed with cervical intraepithelial neoplasia, were randomly assigned to an intervention (n = 27) or a control (n = 26) group.

INTERVENTION

Individualized dietary counseling to increase vegetable and fruit intake.

MAIN OUTCOME MEASURES

Diet was assessed by food frequency questionnaire. Plasma carotenoids and total homocysteine were measured at enrollment and at 6 months follow up.

ANALYSIS

Associations between baseline plasma concentrations of carotenoids and homocysteine and influencing factors were examined with multiple regression analysis. Repeated measures analysis of variance was used to test for group by time effects in these plasma concentrations. Plasma carotenoids at baseline and 6 months in the study groups, and differences in homocysteine concentrations from baseline to 6 months, were compared with independent sample t tests.

RESULTS

Repeated measures analysis of variance showed significant group by time effects (P<.01) in plasma carotenoid and homocysteine concentrations. In the intervention group, total plasma carotenoids increased by an average of 91%, from 2.04+/-0.13 (mean+/-standard error of the mean) to 3.90+/-0.56 micromol/L and plasma total homocysteine was reduced by 11%, from 9.01+/-0.40 to 8.10+/-0.44 micromol/L (P<.003). Neither changed significantly in the control group.

APPLICATIONS

Individualized dietary counseling can effectively promote increased vegetable and fruit intake in premenopausal women. This dietary pattern may reduce risk for cancer and other chronic diseases and also promote an improvement in folate status.

Neuropeptide Y (NPY) levels in alcoholic and food restricted male rats: implications for site selective function

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 content of microdissected brain regions were determined. Neither long-term alcohol ingestion nor caloric restriction were associated with major decrements in copulatory behavior. Long-term alcohol ingestion was associated with decrements in erectile function ex copula. Long-term alcohol ingestion was also associated with: (i) a moderate degree of hypertension; (ii) a failure to gain weight; (iii) decrements in circulating levels of LH, testosterone, and ACTH (but not progesterone); and (iv) increased corticosterone levels. Long-term alcohol ingesting and calorically-restricted rats exhibited alterations in daily feeding patterns. These physiological changes in response to long-term alcohol ingestion or caloric restriction were associated with neural site-selective differences in NPY content. Elevated NPY in the paraventricular nucleus was associated with voluntary (as in alcohol ingestion) or involuntary (as in caloric restriction) reductions in food intake. Differences in NPY in the suprachiasmatic and ventromedial nuclei were associated with the differences in feeding patterns. The decrements in hormone levels were associated with higher levels of NPY in the median eminence and in the arcuate nucleus.

Effects of angiotensin II on sexual function, blood pressure, and fluid intake are differentially affected by AT-1 receptor blockade

We have previously reported that third ventricular administration of angiotensin II (ANG II) immediately before mating tests suppressed copulatory behavior in male rats. The present studies examine the effects of short- (3 days) and long-term (21 days) intracerebroventricular (i.c.v.) infusion of ANG II (6 microg/h), on parameters of copulatory behavior, fluid intake, and blood pressure in sexually experienced male Long Evans rats. Further, to test the hypothesis that suppression of masculine copulatory behavior by ANG II involves interaction with the angiotensin AT-1 receptor, a highly selective nonpeptide antagonist (L-158,809) was administered in the drinking water (25 mg/liter) to a group of ANG II-infused animals. I.c.v. infusion of ANG II was associated with increases in systolic blood pressure and fluid intake. In copulatory tests after 3, 9 and 15 days of infusion, rats infused with ANG II exhibited increased latencies to the initiation of copulatory behavior and to ejaculation, as well as increased intervals to reinitiate copulatory behavior after the ejaculation. Administration of L-158,809 blocked the effects of i.c.v. infusion of ANG II on systolic blood pressure and fluid intake. Further, L-158,809 attenuated the effects of i.c.v. infusion of ANG II on parameters of copulatory behavior. Data from this study provide support for a modulatory role for ANG II in the regulation of sexual behavior. In addition, this regulation seems to involve the AT-1 receptor.

Central propranolol and pindolol, but not atenolol nor metoprolol, inhibit sexual behavior in male rats

Are the anti-sexual effects of propranolol and pindolol due to actions within the brain? To answer this, these agents were administered directly into the brain ventricular system (ICV). Additionally, atenolol and metoprolol were evaluated to see whether differential delivery to the brain contributed to the observed lack of effect of systemically administered beta 1-adrenoceptor antagonists. ICV administration of pindolol (45 or 90 micrograms) was followed by a suppression of copulation. At 45 micrograms, inhibition was limited to performance aspects of copulation, whereas at 90 micrograms, decrements in motivational and performance aspects of copulation were evident. ICV administration of propranolol also suppressed copulatory behavior. At 45 micrograms, no significant effects were observed, whereas at 90 micrograms decrements in motivational and performance aspects of copulation were evident. In contrast, ICV administration of the beta 1-adrenoceptor antagonists, atenolol and metoprolol, was not associated with any major modifications in copulatory behavior. We suggest that the inhibitory effects of propranolol and pindolol may involve interactions with 5-HT1A receptors in the CNS. Alternatively, it may be that the adverse effects of pindolol and propranolol are due to the simultaneous blockade of both beta 1- and beta 2-adrenoceptors.

The inhibitory effects of propranolol on genital reflexes in male rats

We have previously reported that propranolol adversely affects sexual behavior in male rats. To elucidate whether the effects of propranolol might involve decrements in ability, we examined two components of sexual function ex copula--ejaculatory reflex capacity and erectile reflexes. In the first study, we examined the effects of various doses of (+/-)-propranolol (1.25-10 mg/kg) administered subcutaneously. Marked inhibition was observed, evidenced by increases in the latency to ex copula ejaculation and to initial erection and decrements in the number of seminal emissions and in the number of erectile reflexes. Analyses of dose-response relationships indicated that the degree of inhibition increased with increasing dose. In the second study, we evaluated the stereo-selectivity of the responses. Both (+)- and (-)-propranolol (1.25 mg/kg) significantly inhibited ejaculatory reflex potential, and although (+)- and (-)-propranolol significantly inhibited erectile reflexes, (-)-propranolol had a greater effect. The data are interpreted to indicate that a) propranolol-induced sexual dysfunction involves both motivational and ability aspects; and b) propranolol-induced inhibition of genital reflexes may be due, at least in part, to mechanisms other than beta-adrenoceptor blockade.

The inhibition of sexual behavior in male rats by propranolol is stereoselective

We have previously reported that administration of racemic mixtures of propranolol was associated with a marked inhibition of mating behavior in male rats. To compare the effects of (+)-propranolol, (-)-propranolol, and (+/-)-propranolol in sexually experienced males, rats ejaculating in four or more mating tests were divided into three groups (N = 16 per group) such that no differences in parameters of copulatory behavior were evidence in preexperimental tests. No major effect of propranolol on parameters of behavior associated with initiation of sexual behavior was evident. In contrast, other measures of behavior were profoundly modified. The ejaculatory threshold, indicated by the number of intromissions preceding ejaculation, was increased after (+)- and (+/-)-propranolol, but not (-)-propranolol. The number of mounts without intromission preceding ejaculation was increased only after (+/-)-propranolol. A decrease in copulatory efficacy was evident after (-)- or (+/-)-propranolol, but not after (+)-propranolol. Increases in ejaculation latency, intercopulatory interval, and postejaculatory interval were observed after (-)- and (+/-)-propranolol, but not after (+)-propranolol. In summary, the present data indicate that the (-) isomer of propranolol is the active form necessary for the inhibitory effects of propranolol on male sexual function. We suggest that this inhibition is due to specific receptor-mediated mechanisms, involving beta-adrenoceptors and 5-HT1A receptor interactions.

Sexual function in altered physiological states: comparison of effects of hypertension, diabetes, hyperprolactinemia, and others to "normal" aging in male rats

In this review, we examine the changes in sexual function that accompany deviations from "normal" physiological states. We propose that the changes one observes in many altered physiological states should not be viewed in isolation. We describe our paradigms for assessing sexual function, and proceed to evaluate how sexual function changes with hormonal deprivation and aging, in rat models for hypertension, in severe hyperprolactinemia, in streptozotocin-induced diabetes, after chronic alcohol intake, after chronic morphine administration, and after exposure to the heavy metal, cadmium. We will provide evidence for the involvement of adrenergic transmitters and two neuropeptides, neuropeptide Y and somatostatin, in the neuroendocrine regulation of sexual behavior. Finally, we compare and contrast the changes observed relative to the changes seen in "normal" aging in rats. The sequence of age-related changes in sexual function is distinct. The first change observed is a decrement in ex copula erectile reflexes. Next are decreases in ejaculatory threshold, followed shortly by increases in initiation and reinitiation of copulation after ejaculation. This is followed by a decrement in the number of males copulating to ejaculation. Finally, there is a failure to initiate the copulatory process. This sequelae is relatively common, being evident after castration, with hyperprolactinemia, and after exposure to cadmium. The data available for sexual function in hypertension is incomplete and modified by the etiology, but a suggestion for this sequelae is seen in SHR. In contrast, sexual dysfunction associated with chronic morphine administration appears to be due to an initial deficit in motivational aspects. Testosterone reverses sexual dysfunction associated with castration, but not with idiopathic sexual inactivity, nor with sexual dysfunction associated with aging, diabetes, or chronic morphine administration. Comparing sexual function in rat models for hypertension, diabetes and chronic ethanol leads to the conclusion that increases in blood pressure, like decreases in testosterone, cannot be the primary causal factor for sexual dysfunction. Age, hormonal history of the subject, and the age at castration influence changes in sexual function. Age-related sexual dysfunction appears to be contributed to by changes in adrenergic-neuropeptidergic, to include sympathetic, systems. Site-specific administration of NPY induces alterations in parameters of copulatory behavior which mimic those seen in aging and the retention of ejaculatory behavior with aging is associated with site-selective attenuation (or reversal) of age-associated changes in NPY content. Yohimbine enhances copulatory activity in castrated and aging rats, and attenuates or reverses the antisexual effects of clonidine, epinephrine and somatostatin.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronic ethanol ingestion alters parameters of mid-latency auditory evoked potentials in male rats

The purpose of this study was to determine the effects of chronic ethanol ingestion on components of mid-latency auditory evoked potentials (MAEPs). Male Sprague-Dawley rats were administered 10% ethanol in drinking water for 10 months. MAEPs were obtained and compared to age-matched controls provided tap water. Data were obtained for varying frequencies (4, 8, 16, 24, and 32 kHz) and intensities (65, 75, and 85 dB sound pressure level). Ethanol treatment was associated with increased latencies, as well as decreased amplitudes of Na and Pa. The effects were most prominent for MAEP component Pa, but also appear for component Na. We suggest that chronic alcohol consumption induces structural and/or neurochemical alterations in substrates for cortical information processing.

Testosterone-induced copulatory behavior is affected by the postcastration interval

A well entrenched hypothesis regarding hormonal action is that as the time interval following hormonal deprivation increases there is a corresponding decrease in the sensitivity of the system to the effects of hormone replacement. With this in mind, we examined the effects of a prolonged period of hormonal deprivation (9 mo), and compared these to the effects of a shorter period (1 month), on the restoration of copulatory behavior and seminal vesicle weights. Castration of sexually vigorous male Long-Evans rats at 6 mo of age was followed by the virtual disappearance of ejaculatory behavior within 1 mo. Testosterone (T) was administered (5 mm or 20 mm T-containing Silastic capsules) either 1 or 9 mo after castration, and copulatory tests were conducted 3, 7, 10, 14, and 17 days later. 5 mmT and 20 mmT were equally effective in restoring behavior in the rats treated 1 mo after castration. In contrast, 5 mmT was more effective in inducing copulatory behavior than 20 mmT in the rats treated 9 mo after castration. The time course to maximal effect was longer in the rats given T 9 mo after castration. Rats were sacrificed 21 days after T administration. Expressed seminal vesicle weights and plasma testosterone were increased in a dose-dependent manner independent of the postcastration interval. These data indicate that somatic and behavioral effects of T are differentially modified by the period of preceding hormonal deprivation.

Cadmium-induced sexual dysfunction does not involve increased hepatic metabolism of testosterone nor increased circulating levels of corticosterone

Sexually experienced male rats were injected IP with 0, 0.3, 1.5, 3.0, or 6.0 mg/kg cadmium chloride. The highest dose was fatal within 48 h of injection. A dose-related deficit in erectile function was observed in ex copula tests 48 h after injection. Copulatory dysfunction was evident in mating tests 72 h after injection. Hepatic mixed function oxidase activity after 0.3 mg/kg injections was not different from controls, but was diminished by 50% in rats treated with 3.0 mg/kg. The higher cadmium doses (1.5 and 3.0 mg/kg) were associated with equivalent and marked reductions in circulating testosterone levels, and lesser decrements in circulating corticosterone levels. The rats treated with 1.5 or 3.0 mg/kg cadmium chloride lost weight (32 +/- 12 and 39 +/- 9 g, respectively). Relative decapsulated adrenal gland weights were markedly increased in rats treated with 3.0 mg/kg. These data indicate that exposure to cadmium is associated with alterations in sexual, hepatic, and adrenal function, with erectile dysfunction occurring at the lowest dose. The effects on copulatory behavior are especially striking because it requires some weeks for copulatory behavior to wane following castration.

Aging-induced decrements in neuropeptide Y: the retention of ejaculatory behavior is associated with site-selective differences

Neuropeptide Y (NPY) has been implicated in the control of reproductive and cardiovascular function. We observed an age-related decrease in the number of males copulating to ejaculation and a moderate systolic hypertension in middle-aged (16- to 17-month-old) rats. NPY content was examined in microdissected brain nuclei in 5 groups of rats: 2 groups of young rats, 1 heterosexually naive and the other ejaculating in 3 successive mating test; 3 groups of middle-aged rats, 1 heterosexually naive, 1 group that had extensive sexual experience but failed to ejaculate in tests at 16.5 months of age, and the third continuing to ejaculate at 16.5 months of age. NPY levels were found to vary depending on the brain area, the age of the animals, and the maintenance of ejaculatory behavior. In sexually naive middle-aged males, NPY levels were uniformly lower than in younger males. There were no differences in NPY levels of young animals, regardless of sexual experience. In the medial preoptic area, the group that retained ejaculatory behavior through 16.5 months of age, had higher levels of NPY than those observed in young sexually experienced rats. In sexually experienced rats that were no longer ejaculating at 16.5 months of age levels were lower than all other groups except the sexually naive middle-aged group. In the hypothalamic arcuate nucleus, levels were equivalent in the young groups and in the middle-aged rats that retained ejaculatory behavior, being greater than in the middle-aged rats that were no longer ejaculating or were sexually naive.(ABSTRACT TRUNCATED AT 250 WORDS)

Benextramine, a putative neuropeptide Y receptor antagonist, attenuates the termination of receptivity

Sexual behavior in female rats is dependent on gonadal steroids. In ovariectomized rats, progesterone treatment typically exerts a biphasic effect on copulatory behavior induced by prior treatment with estradiol. Thus, there is an initial augmentation of the facilitative effect of estradiol occurring 4-10 h after progesterone. This is followed by a profound inhibitory effect, essentially terminating receptivity. We hypothesized that the receptivity terminating effect of progesterone could be due to increased synthesis and release of neuropeptide Y in relevant brain regions. Rats were tested for female sexual behavior 4 h after progesterone (52 h postestradiol). Immediately following this test, benextramine was administered (0, 3, or 15 mg/kg, IP). Subsequently, behavioral tests were administered 24, 48, 72, and 96 h postbenextramine. Benextramine treatment attenuated the inhibitory effects of progesterone on receptivity (lordosis quotients and percent of responding animals) without affecting either proceptive or rejection behaviors. These data suggest that blockade of NPY (and alpha-adrenergic) receptors is associated with selective enhancements of specific components of sexual behavior in female rats. Specifically, blockade of NPY receptors by benextramine is associated with continued receptivity.

Hormones and sexual behavior in relationship to aging in male rats

To determine if the age-related decline in male sex behavior is correlated with hormonal factors, a longitudinal study was conducted. Sexually experienced males were given mating tests every 2 months from 7 through 27 months of age. To study possible relationships between changes in behavior and alterations in hormone levels, blood samples were taken before and after these bimonthly tests. At 23 months, cross-sectional studies were also conducted comparing results to those obtained in 5-month-old males. Significant changes in mating behavior first appeared at 11 months; mount latency, intromission latency, ejaculation latency, postejaculatory interval, and intercopulatory interval were increased. Similarly, detectable decreases in testosterone (T) also occurred at this age. A significant decline in luteinizing hormone (LH) was not seen until 19 months. Correlational analyses revealed small (r less than or equal to -0.29) but significant negative correlations between T and parameters of mating behavior with age. When each age was examined separately, no significant correlations appeared. Plasma T was not predictive of behavioral performance. At 23 months, cross-sectional studies revealed deficits in mounting and penile reflex behavior but ejaculatory reflex capacity was unimpaired. At 28 months, males were decapitated. Only T levels showed a significant effect of age; estradiol, prolactin, and LH were unaffected when compared to 5-month-old males. The data suggest that although there are small and significant negative correlations between circulating testosterone and parameters of mating behavior with advancing age, it is unlikely that the observed decline in testosterone is the primary cause of the age-induced behavioral deficits. It is likely that the major causal factor(s) involves non-hormone-dependent changes within the CNS.

Sexual function and neuropeptide Y levels in selected brain regions in male spontaneously hypertensive rats

Sexual function was examined in spontaneously hypertensive rats (SHR) from 8 to 20 wk of age and compared with normotensive Wistar-Kyoto (WKY) and Long-Evans rats (LE). Blood pressures (evaluated indirectly) were elevated in SHR (185 +/- 2 and 195 +/- 3 mmHg at 16 and 19 wk of age, respectively) relative to WKY and LE (135-144 mmHg). SHR exhibited good copulatory behavior but displayed fewer erections (less than 20% of the number displayed by WKY or LE) in ex copula tests. At the conclusion of the study (20 wk of age), body weights were lowest in SHR, intermediate in WKY, and greatest in LE. Relative weights of testes were greater in SHR, whereas relative weights of accessory organs, pituitary and adrenal glands, and kidneys were equivalent across strains, as were circulating levels of aldosterone. Circulating levels of testosterone were higher in SHR and WKY than in LE. Neuropeptide Y (NPY) levels in the median preoptic and arcuate nuclei were significantly greater in SHR than in WKY or LE, whereas NPY levels in the medial preoptic area and the suprachiasmatic, hypothalamic dorsomedial, and hypothalamic paraventricular nuclei were equivalent in SHR and WKY, with both greater than LE. No strain differences were evident in the medial nucleus of the amygdala, the bed nucleus of the stria terminalis, the median eminence, the anterior hypothalamic nucleus, or the hypothalamic dorsomedial nucleus.

Suppression of copulatory behavior in male rats following central administration of clonidine

Adrenergic transmitters have been implicated in the regulation of male sexual behavior. In the present study the contribution of alpha 2-adrenoceptors, located within the central nervous system, was evaluated. Sexually experienced male Long-Evans rats were implanted with a permanent cannula in either the third cerebral ventricle or, unilaterally, in the medial preoptic area. Baseline mating tests were administered 4, 7 and 10 days after surgery and only males ejaculating (at least) in the 7 and 10 day tests were used. Clonidine-evoked dose-dependent decrements in the number of males mounting, intromitting and ejaculating, with administration into the medial preoptic area more effective than into the 3rd ventricle. In those animals mating, administration of 20 nmol into the 3rd ventricle was associated with decreases in the latency to ejaculation and intercopulatory interval, whereas administration of 2 nmol into the medial preoptic area was associated with increases in these parameters and decreases in the ejaculatory threshold. Administration of yohimbine into the medial preoptic area attenuated the effects of systemically-administered clonidine and the systemic administration of yohimbine completely prevented the copulatory suppression induced by administration of clonidine into the medial preoptic area. It is suggested that central alpha 2-adrenoceptors are important in the control of male sexual behavior and that alterations in adrenergic mechanisms in the medial preoptic area may underlie sexual dysfunction of various etiologies.

Steroid sulfatase activity in the skin of the external ear canal

Steroid sulfatase is an enzyme which has an important role in the complex process of cell desquamation. The specific activity of this enzyme was found to be higher in the epithelium of the deep external auditory canal than in the epithelium of the superficial external canal. We speculate that this steroid sulfatase activity gradient is involved in the outward migration of the keratinocytes of the canal epithelium.

Clonidine suppresses copulatory behavior and erectile reflexes in male rats: lack of effect of naloxone pretreatment

Adrenergic transmitters and opioid peptides are implicated in the regulation of male sexual behavior. In the present studies we examine a possible interaction between these two neurochemical systems in the regulation of components of male sexual behavior. In mating tests, clonidine (0.25 mg/kg, 6 min pretest) induced a profound deficit in intromissive and ejaculatory behavior whereas naloxone (5 mg/kg, 20 min pretest) evinced a facilitation of ejaculatory behavior, evidenced by decreases in the ejaculation latency in the initial copulatory series and by decreases in ejaculation latency and intercopulatory interval in the second copulatory series. Importantly, prior treatment with naloxone did not prevent or attenuate the copulatory suppression induced by clonidine. In ex copula penile reflex tests, clonidine (0.25 mg/kg, 6 min pretest) decreased the incidence of seminal emission and the number of penile responses (erections, cups and flips). Naloxone (5 mg/kg, 20 min pretest) was without effect on any of the parameters of penile reflex activity and, further, failed to prevent or attenuate the erectile suppression induced by clonidine. A final study evaluated the dose-response relationship of clonidine-induced erectile dysfunction. A similar degree of erectile dysfunction was observed after 0.005, 0.025 or 0.25 mg/kg clonidine, whereas 0.0005 mg/kg was without effect. Previous studies demonstrated a dose-dependent inhibition of mounting, intromissive and ejaculatory behavior, with 0.25 mg/kg selectively eliminating ejaculatory behavior in mating tests. These data demonstrate a dose-dependent inhibition of penile reflexes, with inhibition occurring at doses lower than those required to induce copulatory dysfunction. Further, we suggest that opioid receptors sensitive to naloxone blockade are not involved in the clonidine-induced suppression of copulatory or erectile function.

Polymorphism of a 35-48 kDa Plasmodium falciparum merozoite surface antigen

Glycoproteins of the asexual blood stages of Plasmodium falciparum were labelled with radioactive glucosamine and analysed by two-dimensional electrophoresis. Four major glycoproteins were detected in all eight parasite isolates studied. Two of the glycoproteins, designated GP2 and GP4, were invariant among the isolates, while the other two GP1 and GP3 were found to be polymorphic in both their biochemical and antigenic properties. By immunoblotting and immunoprecipitation with specific monoclonal antibodies, the two polymorphic glycoproteins were identified as surface antigens of merozoites.

46-53 kilodalton glycoprotein from the surface of Plasmodium falciparum merozoites

A 46-53 kDa glycoprotein antigen of Plasmodium falciparum merozoites has been identified using a murine monoclonal antibody that inhibits infection of human erythrocytes in vitro. Immunofluorescence screening with the antibody of greater than 250 isolates of the parasite finds the inhibitory epitope expressed by only 18% of strains. The glycoprotein is metabolically labelled with methionine, cysteine, histidine and glucosamine but incorporates little lysine or leucine. It is synthesized early in schizogony and remains, without any apparent processing, on the surface of released merozoites where it is demonstrated by immuno-electronmicroscopy and also by vectorial radio-iodination.

A possible role for angiotensin II in the regulation of male sexual behavior in rats

To investigate the possibility that angiotensin II (AII) is involved in the regulation of male sexual behavior, AII was injected intraventricularly into sexually experienced male rats immediately prior to mating tests. Third ventricular administration of 0.48 nmol AII resulted in an increased latency to the initiation of copulatory behavior (625% of control values), and administration of 4.8 nmol had a similar effect on initiation latencies (650% of control values) and, additionally, significantly increased the number of intromissions preceding ejaculation (the ejaculatory threshold, to 130% of control values) and the interval to reinitiate copulatory behavior after ejaculation (the postejaculatory interval, to 125% of control values). Water intake was affected only by the higher dose of AII, with no animals drinking in the 15 minutes following saline or 0.48 nmol AII and 69% of the rats treated with 4.8 nmol AII drinking (mean intake 1.5 +/- 0.26 ml for those rats drinking). These data demonstrate that AII can suppress male sexual behavior, and that this suppression is not due simply to a stimulation of drinking.

Chronic morphine and testosterone treatment. Effects on sexual behavior and dopamine metabolism in male rats

The effects of sustained delivery of morphine and/or testosterone (T) on male rat copulatory behavior, penile reflexes and dopaminergic metabolism in selected brain regions were examined. Castration was followed by (1) a decrease in the number of male rats exhibiting intromissive and ejaculatory behavior in mating tests, (2) decreased erections in ex copula tests, and (3) increases in dopamine and dihydroxyphenylacetic acid (DOPAC) concentrations in the mediobasal hypothalamus (MBH) and the preoptic area-anterior hypothalamus (POA-AH). The decreased incidence of copulatory behavior and penile reflexes seen after castration was effectively prevented by a 4-day treatment with 5-mm T-containing Silastic capsules. Chronic morphine implants, conversely, accentuated the castration-induced decrements in copulatory behavior and prevented the 5-mm-T-induced facilitation, but did not alter the number of animals displaying erection (although the number of erections displayed by testosterone-treated rats was reduced) in ex copula tests. Treatment of castrated rats with 5 mm T, but not morphine alone, nor the combination of 5 mm T plus morphine, significantly reduced dopamine and DOPAC levels in the MBH. In the POA-AH, 5 mm T was without effect, whereas morphine, alone or in combination with 5 mm T, reduced the levels of dopamine and DOPAC. These data suggest that (1) the decline in sexual behavior induced by chronic morphine is primarily due to a failure of sexual arousal, and not of erectile ability, and (2) although the decline in sexual activity seen after castration is associated with alterations in dopaminergic metabolism, the effects of morphine and testosterone on sexual activity are opposite and dissociated from alterations in dopaminergic metabolism.

Chronic morphine and testosterone treatment: effects on norepinephrine and serotonin metabolism and gonadotropin secretion in male rats

The effects of sustained-release implants of morphine (M) and/or testosterone (T) on serum gonadotropin levels and norepinephrine (NE) and serotonin (5-HT) metabolism in brain regions were examined. While 4 days of M or 5 mm [corrected] T treatment were without significant effect, the combination dramatically decreased circulating levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Castration increased NE content of the mediobasal hypothalamus (MBH), and although M, 5 mm [corrected] T, or their combination significantly reduced NE levels in the MBH, they remained elevated compared to intact or 30 mm [corrected] T-treated rats. Further, in the MBH no differences in normetanephrine (NME) levels, nor in NME:NE ratios, nor 5-HT metabolism were evident. In the preoptic area-anterior hypothalamus, NE or 5-HT metabolism were not altered by castration and M and/or T. These results show that M and T interact to suppress LH and FSH release in the apparent absence of any appreciable effect on hypothalamic monoamines.

Triton-labile antigens in flagella isolated from Giardia lamblia

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 approximately 30 kD structural giardins of the cytoskeleton. However, on sodium dodecyl sulphate-polyacrylamide gels, the mobilities of individual flagellar polypeptides do not correspond exactly to the cytoskeleton bands, and, unlike the cytoskeleton proteins, the flagellar components are easily extracted by Triton demembranation. The pattern of flagellar isoforms after isoelectric focussing (IEF) and electrophoresis in two dimensions is also clearly different from that of the cytoskeleton proteins. The fact that at least some approximately 30 kD flagellar antigens are localised by immunofluorescence specifically in the two ventral flagella suggests that these proteins may be components of the paraflagellar structures found beneath the membrane of these organelles. In electron micrographs of the isolated flagella, the paraflagellar rods are seen to bridge the membrane to three adjacent doublet microtubules of the axoneme.

Alpha 2-adrenoceptor blockade attenuates feeding behavior induced by neuropeptide Y and epinephrine

Neuropeptide Y (NPY, 0.47 nmol) and epinephrine (28.9 nmol) evoked robust, and quantitatively similar, increments in food intake and local eating rate following administration into the third cerebral ventricle (IIIV). Whereas IIIV pretreatment with phentolamine (71 nmol), a nonselective alpha-adrenoceptor antagonist, or prazosin (9.5 nmol), a selective alpha 1-adrenoceptor antagonist, was without effect on NPY-induced feeding behavior, pretreatment with the alpha 2-adrenoceptor antagonist yohimbine (15 nmol) dramatically attenuated the stimulatory effects of NPY or epinephrine on both food intake (by over 50%) and local eating rate. Additionally, yohimbine administered alone was associated with a stimulatory effect on food intake for the periods of 80-110, and 110-140 minutes posttreatment. These data demonstrate that feeding behavior induced by IIIV administration of NPY or epinephrine is attenuated by prior blockade of alpha 2-adrenoceptors and suggest that, as in other systems innervated by neurons displaying NPY and adrenergic transmitter colocalization, the effects of NPY on feeding behavior may, at least in part, be mediated via alpha 2-adrenoceptors.

Control of feeding and sexual behaviors by neuropeptide Y: physiological implications

Recent evidence suggests that a variety of hypothalamic neuropeptides may mediate interneuronal communication to coordinate diverse neuroendocrine and behavioral functions. In this work, we describe the effects of neuropeptide Y (NPY) on feeding and sexual behaviors. We observed that central administration of bolus NPY stimulated a robust, dose-related feeding response in satiated male and female rats. Continuous NPY receptor activation also evoked dose-related, intermittent feeding in a manner normally observed during nocturnal feeding. It appears that the paraventricular nucleus in the hypothalamus may be the primary site of NPY action because the anticipated reciprocal changes in NPY concentrations, in response to food deprivation followed by ad libitum food intake, occurred only in this site. Additional findings revealed that NPY-induced feeding may follow either substantial reduction or complete restraint of an inhibitory influence on feeding mediated by alpha 2-adrenoreceptor systems in satiated rats. Further, NPY was found to suppress male and female sexual behaviors. The suppressive effects on sexual behavior were apparent prior to or at the time of the onset of feeding after NPY administration. These observations may provide a neurochemical basis for clinical and animal studies on disorders of feeding associated with diminished reproductive functions.

Relation of autogrooming to sexual behavior in male rats

Grooming and penile reflexes were studied in male rats that were restrained in supine position with the penile sheath retracted or were free to copulate with sexually receptive females. In Experiment 1 there was a reliable concordance in supine males between the tendency to groom and the tendency to display penile reflexes. In Experiment 2 we analyzed the sequential organization of grooming and genital events in supine tests. It was assumed that many or most episodes of ventral grooming would have been genital grooming had access to the genitalia not been prevented by restraint. Paw grooming tended to precede clusters of penile responses, whereas ventral grooming started after the onset of erections. Experiment 3 was an exploration of grooming in the context of copulation, rather than supine restraint. Males groomed their genitalia immediately after all intromissions and after all mounts that ended mount bouts. The duration of grooming was not affected by whether or not intromission occurred. Finally, in Experiment 4 we observed genital and nongenital grooming and recorded electromyographic (EMG) activity from the striated bulbospongiosus muscle (mBS) of the penis in freely moving rats. Consistently, mBS activity led to genital grooming with a short latency, whereas nongenital grooming rarely led to genital grooming, and EMG activity was not associated with nongenital grooming nor did it tend to follow after genital grooming was initiated.(ABSTRACT TRUNCATED AT 250 WORDS)

Topography of epitopes on a polymorphic schizont antigen of Plasmodium falciparum determined by the binding of monoclonal antibodies in a two-site radioimmunoassay

The topographic distribution of common and variant epitopes on two divergent allelic forms of the 185-205K schizont glycoprotein of Plasmodium falciparum were studied by a two-site radioimmunoassay using monoclonal antibodies. Similarities in the conformation of the two molecules were apparent. On both antigens two distinct regions were mapped, each comprising of both strain-common and polymorphic epitopes. Epitopes common to the two PSAs were found to be closely associated with different variable epitopes in tertiary structure. It is suggested that this may contribute to parasite evasion of the host immune response.

Effects of apomorphine on sexual behavior in young and middle-aged rats

Apomorphine (APO), the prototypical dopamine agonist, produced different effects on the copulatory patterns of sexually vigorous male rats depending on the dose, the time between treatment and behavioral observation and the age of the animals. Prior to any drug treatment, middle-aged males (13 months of age) exhibited prolonged latencies to ejaculation and intervals between intromissions when compared to young male rats (3 months of age). In mating tests to young male rats initiated six minutes after treatment, administration of low doses of APO was followed by reductions in the ejaculatory threshold (0.05-0.8 mg/kg). The greatest reduction in the ejaculatory threshold was observed after administration of 0.4 mg/kg APO. No such facilitation of ejaculatory behavior was evident in the middle-aged males. Age-related differences in APO-induced changes in ejaculation latency (0.05-0.8 mg/kg), intromission frequency (0.05-0.4 mg/kg), copulatory efficacy (0.2 and 0.8 mg/kg) and intercopulatory interval (0.8 mg/kg) were evident. Doses of APO above 0.4 mg/kg in young males and above 0.2 mg/kg in middle-aged males elicited dose-related decreases in the number of rats engaging in copulatory activity, with 3 mg/kg effecting a virtual elimination in both age groups. In mating tests initiated 60 minutes after treatment, no decrease in the number of rats engaging in copulatory activity was seen in the young animals, and 3 mg/kg caused only a minor reduction in the number of middle-aged males achieving ejaculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuropeptide Y (NPY)-induced feeding behavior in female rats: comparison with human NPY ([Met17]NPY), NPY analog ([norLeu4]NPY) and peptide YY

Porcine neuropeptide Y (pNPY) administered into the third ventricle of the brain is known to elicit a powerful feeding response in steroid-treated ovariectomized and intact male rats. The present study compared the effects of pNPY and 3 structurally related peptides, human NPY (hNPY), an analog of NPY (NPY-A, [norLeu4]NPY) and peptide YY (PYY) on feeding behavior in intact female rats. Intraventricular administration of pNPY, hNPY, NPY-A and PYY over a dose range of 0.5 to 10 micrograms evoked feeding behavior to a varying extent. Cumulative food intake during 60 and 120 min was increased in a dose-related fashion at 0.5 and 2.0 microgram for the 4 peptides. Whereas the 10-micrograms dose of pNPY evoked a feeding response smaller than that seen after 2 micrograms, the responses to either 10 micrograms hNPY or 10 micrograms PYY were similar to that seen after 2 micrograms. The effects of these peptides on the time spent eating were quite different: while pNPY increased the time spent eating, this effect was not dose-related, whereas hNPY, NPY-A and PYY produced dose-related increments in the time spent eating. The most dramatic increment in local eating rate was observed after 2.0 micrograms pNPY, with lesser increments seen after 2.0 microgram hNPY and NPY-A. This increased local eating was apparently responsible for the highest cumulative food intake observed. These results demonstrate that (a) 2 micrograms pNPY is equally effective in stimulating feeding behavior in intact female rats as it is in steroid-primed ovariectomized female and intact male rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of a selective alpha 1-adrenoceptor agonist, methoxamine, on sexual behavior and penile reflexes

Methoxamine, an adrenergic agonist with selectivity for the alpha 1-adrenoceptor, when administered intraperitoneally 10 minutes prior to mating tests (1 to 5 mg/kg), effected reductions in the ejaculatory threshold, evidenced by a decrease in the number of intromissions preceding ejaculation. In mounting tests after penile anesthetization, a test which specifically assesses sexual motivation, 3 mg/kg methoxamine was without a stimulatory effect. Further, in penile reflex tests (ex copula) 1 mg/kg methoxamine was without effect, whereas 5 mg/kg decreased the number of erections, cups and flips per test, and increased the incidence of seminal emission. These data indicate a facilitation of the ejaculatory mechanism, both in and ex copula, coupled with an inhibition of erectile responses for moderate doses of methoxamine. Treatment of male rats with the alpha 2-adrenoceptor agonist clonidine (0.25 mg/kg, IP, five minutes pretest) drastically reduced the number of animals exhibiting intromissive and ejaculatory behavior in mating tests. This suppressive effect of clonidine was not prevented by prior treatment with methoxamine (3 mg/kg, 10 minutes pretest and five minutes preclonidine). Further, ST-91, a polar analog of clonidine which does not readily enter the central nervous system, was without effect on male sexual behavior. Since (1) the effects of methoxamine administration are not of similar quality or magnitude to those reported earlier after yohimbine, an alpha 2-adrenoceptor antagonist, (2) since concurrent stimulation of alpha 1- (by methoxamine) and alpha 2- (by clonidine) adrenoceptors is followed by a suppression of sexual behavior similar to that seen after clonidine alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification and characterisation of proteins associated with the rhoptry organelles of Plasmodium falciparum merozoites

We describe antigens of Plasmodium falciparum recognised by murine monoclonal antibodies which by immunofluorescence react with the rhoptry organelles of the extracellular merozoite stage. Immunoblotting shows that the antibodies recognise two major parasite antigens of Mr 82 and 65 kilodaltons (kDa). Immunoprecipitations from detergent extracts of [35S]-methionine-labelled parasites show that the 82-kDa and 65-kDa antigens are parasite proteins. Pulse-chase experiments on synchronous parasite cultures show that the 82-kDa protein is synthesised during early schizogony and is later processed into the 65-kDa antigen in segmenting schizonts. In Nonidet P-40, these antigens are non-covalently associated with two other proteins of 40 kDa and 42 kDa. The 40/42-kDa doublet is synthesised in parallel with the 82 kDa antigen and persists, apparently unchanged, till the end of the cell cycle.

Plasma membrane isolated from Giardia lamblia: identification of membrane proteins

Two methods are introduced for preparing plasma membranes from Giardia lamblia trophozoites. Isolated membranes were purified by centrifugation on either a sucrose step-gradient or a self-generated Percoll gradient, where they band at a density of approximately 1.04 g ml-1. In pure fractions, membranes formed vesicles or extensive sheets. Electron microscope profiles show that they are asymmetric with a thin filamentous coat on one side. Membrane proteins were resolved by SDS/PAGE. They included a major component of apparent Mr 75,000 (75 kDa), and additional bands detectable by gel staining at 58 kDa, 54 kDa, 32 to 38 kDa (5 bands), 22 kDa, and 15 to 20 kDa. To probe the surface location of proteins, gels were also prepared from Giardia cells that were surface radio-iodinated using the immobilised catalyst IODOGEN. The 75 kDa membrane protein was strongly labelled in the corresponding autoradiograph, also the bands at 58 kDa and 54 kDa, the 22 kDa polypeptide, and some faint bands not resolved in the isolated membrane preparations. The set of close-running bands at 32 to 38 kDa were not iodinated. The labelled 58 kDa and 54 kDa proteins comigrated with alpha and beta-tubulins. Controls showed that cytoskeleton and flagellar tubulins were not iodinated in this experiment, indicating that the labelled tubulin is surface-derived. The principal approximately 75 kDa surface protein identified in isolated membranes probably corresponds to an iodinatable and antibody-precipitated "82 kDa" antigen reported previously.

Immunocytochemical differentiation of microtubules in the cytoskeleton of Giardia lamblia using monoclonal antibodies to alpha-tubulin and polyclonal antibodies to associated low molecular weight proteins

In interphase trophozoites of Giardia lamblia, separate populations of microtubules constitute the four parts of the mastigont apparatus: flagella, ventral disc, funis and median body. Antigenic differences between the tubules have been investigated by light and electron immunocytochemistry after labelling with two monoclonal antibodies to alpha-tubulin (YL 1/2 and YOL 1/34 clones), and with polyclonal antibodies to Giardia tubule-associated proteins. Both anti-tubulins stained all tubules after isolated structures were fixed in formaldehyde, but different patterns of reactivity were shown by unfixed tubules. YL 1/2 antibodies labelled flagellar axonemes and basal bodies, funis and median body tubules. Disc microtubules were mostly unlabelled, but the antibody bound strongly to the outer edge of the disc where the ends of tubules are embedded. YOL 1/34 antibodies stained disc tubules uniformly, and cross-reacted with the median body but not with tubules of axonemes, basal bodies or funis. Antibodies to giardins 14A and 14B (approximately 30 000 Mr filament-forming proteins) localized these proteins in the microribbons attached to disc microtubules. The median body was also labelled by anti-giardins, indicating an ontogenetic relationship between this organelle and the ventral disc. A second set of approximately 30 000 Mr proteins with no immunoreactivity to anti-giardin was found in flagella purified without removing flagellar membranes. These polypeptides were Triton-soluble and therefore probably originated from an extra-axonemal site. A rabbit antiserum to the labile flagellar proteins specifically stained the two ventral flagella, but not the other six flagella on this cell.

Failure of pimozide and metergoline to antagonize the RDS-127-induced facilitation of ejaculatory behavior

Metergoline, a serotonin-receptor antagonist, when administered in either an ascorbic acid or ethanol containing vehicle was without effect on male rat copulatory behavior (3 mg/kg, 90 minutes pretest). When initially dissolved in several drops of acetic acid, however, the same dose of metergoline dramatically suppressed male rat sexual behavior. Thus, one-half of the treated rats failed to intromit and ejaculate, and those displaying the behaviors exhibited elongated intercopulatory and postejaculatory intervals. The administration of the putative dopamine-receptor agonist RDS-127 (2-N,N-di-n-propylamino-4,7-dimethoxyindane; 3 mg/kg, six minutes pretest) induced seminal emission ex copula and drastically reduced intromission frequency and ejaculation latency in copula, as well as effecting lesser reductions in the intercopulatory and postejaculatory intervals in two sequential copulatory series. RDS-127-induced seminal emission was effectively antagonized by pretreatment with the dopamine-receptor antagonist pimozide (250 micrograms/kg, two hours pretest), but not by pretreatment with metergoline. In contrast to seminal emission ex copula, pimozide pretreatment failed to antagonize the RDS-127 facilitation of ejaculatory behavior in copula. Metergoline pretreatment also failed to antagonize the RDS-127-induced facilitation of ejaculatory behavior in copula. However, RDS-127 prevented the suppressive effects of metergoline treatment, suggesting that RDS-127 has some agonistic action at serotonergic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term weekly gonadal steroid treatment: effects on plasma prolactin, sexual behavior and hypothalamic-preoptic area catecholamines

Treatment of intact female rats with weekly injections of estradiol benzoate followed 48 h later by progesterone reliably induced high levels of sexual behavior. After 15-20 treatments, 25% of one group of females became refractory to the sexual-activity-inducing effects of ovarian steroids. The apparent deficit in sexual behavior could not be attributed to variation in prolactin secretion, as long-term steroid treatment resulted in greatly elevated circulating prolactin levels (greater than 1 microgram/ml) which were equivalent in good sexual responders (lordosis quotient, LQ greater than or equal to 90) and sexually refractory females (LQ less than or equal to 20). In control rats, short-term steroid treatment (5 weeks) decreased dopamine (DA) and dihydroxyphenylacetic acid (Dopac) concentrations in the median eminence (ME) and induced good sexual behavior. Interestingly, a similar pattern of decreases in DA and Dopac levels of ME was observed in those long-term-treated rats displaying good sexual behavior but not in the sexually refractory females. Further, a significant increase in DA concentration in the preoptic-anterior hypothalamic area of the sexually refractory females was observed. These data are interpreted to suggest that severe and chronic elevations in circulating levels of prolactin, induced by chronic ovarian steroid treatment, are not universally associated with a disruption of sexual behavior and increased dopaminergic function in the ME, seen in females with normal sexual behavior, was conspicuously absent in female rats that became refractory to the sexual-behavior-inducing effects of ovarian steroids.

Neuropeptide Y stimulates feeding but inhibits sexual behavior in rats

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, 0.47, 2.3 nM) uniformly elicited feeding with a latency of about 15 min in male rats. With the most effective dose, 0.47 nM, the increased food intake was due to an increased local eating rate. In contrast, the pattern of feeding behavior after a related peptide, rat pancreatic polypeptide (rPP), was quite different and less impressive. During the first hour, only one ivt dose of rPP (0.45 nM) evoked an increase in food intake, due to an increased time spent eating. Further, the effects of NPY on food intake were greater during the nocturnal period. Interestingly, increased food intake in nocturnal tests (4 h) was due solely to augmented intake during the first 60 min after ivt administration. In mating tests, initiated 2 h after the onset of darkness and 10 min after ivt administration of peptide, all but the lowest dose of NPY (0.01 nM) drastically suppressed ejaculatory behavior. Most rats treated with higher doses of NPY (0.02, 0.12, or 0.47 nM) mounted and intromitted only a few times before the cessation of sexual activity, and elongated latencies to the initial mount and intromission were observed. In contrast to the dramatic NPY-induced suppression of ejaculatory behavior, rPP (0.11 and 0.45 nM) was without effect on copulatory behavior. To substantiate further that the impairment of sexual behavior seen in NPY-treated rats was not due to an attenuated sexual ability, an additional experiment was performed. Penile reflexes, including erection, were monitored 10 min after ivt injection of NPY (0.12 nM), rPP (0.11 nM), or saline. No effect of NPY or rPP was observed on the proportion of rats showing erection or latency to initial erection, or in the number of erections per test. In fact, a slight facilitation of penile dorsiflexion responses was seen after NPY. These findings suggest that NPY selectively depresses sexual motivation in the male rat. In ovariectomized female rats responding to estrogen plus progesterone with a good level of sexual receptivity (lordosis quotient greater than 70), ivt saline and 0.01 nM NPY were without effect on sexual behavior.(ABSTRACT TRUNCATED AT 400 WORDS)

Central effects of RDS-127: sexual behavior after intracerebroventricular administration and in vitro receptor binding studies

RDS-127, in a dose-related manner, induced seminal emission ex copula after intracerebroventricular (i.c.v.) administration. In mating tests initiated 6 min after i.c.v. administration, RDS-127 induced decreases in ejaculation latency and intromission frequency, with some rats ejaculating on the initial intromission. Additionally, penile reflexes were eliminated by 150 micrograms and 600 micrograms, but not by an intermediate dose. In in vitro radioligand binding studies, RDS-127 potently displaced [3H]DPAT binding to 5-HT1A sites in rat cortex (Ki = 14 +/- 4 nM) and was only moderately effective in displacing [3H]spiperone binding to dopaminergic D2 sites in rat striatum. RDS-127 was essentially ineffective at 5-HT1B sites labeled by [3H]5-HT in rat striatum (Ki = 13 000 +/- 4 000 nM). These data demonstrate that centrally administered RDS-127 mimics the previously reported alterations in sexual behavior after systemic treatment and that RDS-127 is a high affinity 5-HT1A agent with low affinity at the 5-HT1B binding site.

Testosterone is not required for the enhancement of sexual motivation by yohimbine

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 rats up to 91 days after castration. Finally, yohimbine induced mounting in intact, nonreceptive female rats. These observations indicate that testosterone is not required for the enhancement of sexual motivation by yohimbine and support the suggestion that alpha 2-adrenoceptors are involved in the modulation of sexual arousal.

Effects on penile reflexes and plasma hormones of hyperprolactinemia induced by MtTW15 tumors

The effects of severe hyperprolactinemia induced by MtTW15 tumors (prolactin- and growth-hormone-secreting pituitary adenoma) on penile reflex activity and blood hormones were examined. There was no significant adverse effect of hyperprolactinemia on penile reflexes at 7, 14, or 21 days after tumor inoculation. However, a virtual elimination of penile reflex activity was observed 34 days after inoculation. Additionally, significant decrements in serum testosterone and dihydrotestosterone and an elevation in progesterone were seen at this time concomittant with greatly increased prolactin levels. The results suggest that erectile dysfunction may contribute to hyperprolactinemia-induced copulatory failure.

Purchasing medical equipment: a protocol for decision making

In light of today's tight hospital financial picture caused by Medicare's prospective payment system and local constraints, capital expenditures must be made with great care and forethought. The process for purchase decision making should assess the need for the device; specifically identify what is required; carefully evaluate the product via technical, clinical, and user studies; collate the results for committee decision making; and plan for the introduction and support of the product through its lifetime. A case study of the acquisition of a neonatal monitoring system is presented.

Evidence for the modulation of sexual behavior by alpha-adrenoceptors in male rats

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 animals mounting and intromitting. These effects were maintained for at least 4 h after treatment. Prazosin, another antihypertensive (but acting by blockade of alpha 1-adrenoceptors), increased latencies to initiation of copulation, to ejaculation, and to reinstatement of copulation following ejaculation. Additionally, prazosin (1 mg/kg) pretreatment failed to attenuate or prevent the clonidine-induced suppression of ejaculation. In contrast, yohimbine, a drug which preferentially blocks alpha 2-adrenoceptors (2 mg/kg, 20 min prior to mating tests), caused a facilitation of copulatory behavior as evidenced by drastic decreases in ejaculation latency and intercopulatory and postejaculatory intervals. Pretreatment with yohimbine completely prevented the clonidine-induced suppression of ejaculation, while clonidine attenuated the facilitatory effects of yohimbine, suggesting a competitive interaction. These data lead to the suggestion that increased excitatory adrenergic activity results in increased sexual arousal either by blockade of alpha 2-or stimulation of alpha 1-adrenoceptors. Alternatively, stimulation of alpha 2-or blockade of alpha 1-adrenoceptors results in diminished sexual motivation. While the precise implications of this animal research for the clinic are as yet unclear, further research could lead to important developments in the pharmacological treatment of sexual dysfunctions.

Enhancement of sexual motivation in male rats by yohimbine

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. These observations lead to the suggestion that alpha-adrenoceptors are important modulators of sexual arousal in intact male rats. These results indicate that pharmacological treatment of sexual (libido) dysfunction may be useful.

Neuropeptide Y and human pancreatic polypeptide stimulate feeding behavior in rats

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 benzoate plus progesterone significantly increased the number of animals feeding, and total food intake in tests conducted during the light phase of the day. Administration of neuropeptide Y, 2 or 10 micrograms, induced feeding in all rats, and food intake was 3 times greater than that observed after human pancreatic polypeptide injection. These findings imply that neuropeptide Y, or a closely related pancreatic polypeptide-like neuropeptide, plays an important role in neural regulation of feeding behavior.

Further studies on alterations in male rat copulatory behavior induced by the dopamine-receptor agonist RDS-127

Pharmacologic dopamine receptor stimulation by RDS-127 (2-N,N-di-n-propylamino-4,7-dimethoxyindane) resulted in qualitatively different changes in the mating pattern depending on the dose administered and time elapsed between treatment and behavioral observation. A low dose (0.25 mg/kg) selectively increased the latency to ejaculation whereas a high dose (3.0 mg/kg) decreased ejaculation latency and intromission frequency (both indicators of ejaculatory efficiency) when behavioral observations were begun 30 minutes after intraperitoneal administration. Intermediate doses (0.5, 1.0, and 2.0 mg/kg) did not alter the time required to achieve ejaculation but did lower the number of intromissions preceding ejaculation. These dose-dependent actions resemble the effects of dopaminomimetics (reported by others) on locomotor activity. When mating tests were conducted shortly (less than five minutes) after drug administration, the induction of ejaculation by the high dose was enhanced. At this time, as well as after a prolonged delay (two hours), signs of decreased arousal (longer intromission latencies) were also observed. However, the postejaculatory refractory period was altered in a time-dependent fashion, viz: it was shortened closest to the injection time, not altered 30 minutes after treatment, and increased two hours after RDS-127 administration. Finally, RDS-127 induced seminal emission (ex copula) in 2.9 +/- 0.9 (S.E.) minutes, and these emissions did not differ in weight from normal spontaneous (diurnal) seminal emissions. The RDS-127-induced seminal emission was not followed by a refractory period of similar magnitude to that seen after ejaculation in copula. The data are interpreted in terms of the involvement of dopamine receptor subtypes in the modulation of masculine sexual behavior.

Effects of a potent dopamine receptor agonist, RDS-127, on penile reflexes and seminal emission in intact and spinally transected rats

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 copulating animals. The incidence of seminal emission was significantly elevated by RDS-127 but penile reflexes were present in only 8% of the drug-treated rats, compared to 59% of controls. In Experiment 2, seminal emission was induced 2.3 +/- 0.4 (S.E.) minutes from injection of RDS-127. Animals which responded to RDS-127 with multiple emissions had significantly lower ejaculation latencies during copulatory tests conducted prior to drug treatment than animals which had no or only single seminal emissions following RDS-127 injection. Spontaneous seminal emission in the 3 day period initiated 2 hours after RDS-127 injection was unaffected by the drug. Spontaneously produced plugs were approximately twice the weight of those induced by RDS-127. In Experiment 3, seminal emission was induced in spinally transected rats 1.7 +/- 0.4 minutes following RDS-127 administration, whereas drug treatment attenuated the enhancement of penile reflexes observed following midthoracic spinal transection. These experiments suggest that a spinally-mediated dopaminergic mechanism is capable of stimulating seminal emission acutely in the rat and inhibiting the display of penile reflexes by the supine animal.

Effects of a novel dopamine-receptor agonist RDS-127 (2-N,N-di-n-propylamino-4,7-dimethoxyindane), on hormone levels and sexual behavior in the male rat

Selective changes in the mating pattern occurred 30 minutes following administration of RDS-127 (3.0 mg/kg, IP) to sexually experienced adult male rats. Marked decreases in intromission frequency and ejaculation latency were observed. These data indicate a potent effect upon conummatory mechanisms underlying copulatory behavior. The lack of effect upon arousal state was further demonstrated utilizing a "mounting test" (in which the penis is anesthetized by topical application of tetracaine hydrochloride). No difference in mounting behavior was seen. Seminal plugs were noted in a large percentage of treated animals at the time of anesthetic application. Additionally, a six-fold decrease in plasma prolactin and a lesser decrement in plasma luteinizing hormone were evident. Finally, in sexually experienced castrate animals, RDS-127 induced mounting in two thirds and intromissive and ejaculatory patterns in one third of the treated animals, 35 days postcastration. These effects were greatly attenuated by 56 days postcastration. The selective alteration of consummatory mechanisms, with little or no effect upon arousal status, suggests a neurochemical separation of these two components in the intact male rat.