IL-15 Superagonist NAI in BCG-Unresponsive Non-Muscle-Invasive Bladder Cancer

IL-15 Superagonist NAI in BCG-Unresponsive NMIBCIn this trial, patients with BCG-unresponsive bladder CIS with or without Ta/T1 papillary disease or BCG-unresponsive high-grade Ta/T1 papillary NMIBC were treated with intravesical NAI, an IL-15 superagonist, plus BCG. Primary end points were CR at 3 or 6 months for patients with CIS disease and DFS rate at 12 months for those with high-grade Ta/T1 disease. CR rate was 71% (58 of 82 patients), and the DFS rate was 55.4%.

Phase I Trial Characterizing the Pharmacokinetic Profile of N-803, a Chimeric IL-15 Superagonist, in Healthy Volunteers

The oncotherapeutic promise of IL-15, a potent immunostimulant, is limited by a short serum t _1/2 The fusion protein N-803 is a chimeric IL-15 superagonist that has a >20-fold longer in vivo t _1/2 versus IL-15. This phase 1 study characterized the pharmacokinetic (PK) profile and safety of N-803 after s.c. administration to healthy human volunteers. Volunteers received two doses of N-803, and after each dose, PK and safety were assessed for 9 d. The primary endpoint was the N-803 PK profile, the secondary endpoint was safety, and immune cell levels and immunogenicity were measures of interest. Serum N-803 concentrations peaked 4 h after administration and declined with a t _1/2 of ∼20 h. N-803 did not cause treatment-emergent serious adverse events (AEs) or grade ≥3 AEs. Injection site reactions, chills, and pyrexia were the most common AEs. Administration of N-803 was well tolerated and accompanied by proliferation of NK cells and CD8⁺ T cells and sustained increases in the number of NK cells. Our results suggest that N-803 administration can potentiate antitumor immunity.

Antibacterial activity of silver nanoparticles against field and reference strains of Mycobacterium tuberculosis, Mycobacterium bovis and multiple-drug-resistant tuberculosis strains

Tuberculosis (TB) is an endemic disease in animals and humans in Egypt. This study aims to investigate the antimycobacterial activity of silver nanoparticles(AgNPs) by determining the minimal inhibitory concentration (MIC) of AgNPs, using the microplate Alamar blue assay. The AgNPs were chemically synthesised and their form and size were characterised by ultraviolet-visible absorption spectrophotometry, transmission electron microscopy and X-ray diffraction.The reference strains of Mycobacterium bovis and Mycobacterium tuberculosisH37Rv, and one multiple-drug-resistant (MDR) strain of M. tuberculosis were tested, as well as clinical isolates of M. bovis and M. tuberculosis. The AgNPs were tetrahydral with a few spherical particles and an average particle size of 50 nm. The mycobacterial strains were varied with MICs of AgNPs. Both reference strains of M. tuberculosis and M. bovis, in addition to the MDR strain of M. tuberculosis, were successfully inhibited by AgNPs at MICs of 1 ?g/ml, 4 ?g/ml and 16 ?g/ml, respectively, whereas clinical isolates of M. bovis and M. tuberculosis were inhibited at MIC values of 4-32 ?g/ml and 1-16 ?g/ml, respectively. The AgNPs showed an in vitro chemotherapeutic effect against Mycobacterium spp.Thus, they can be used to treat TB not only in humans but also in animals, and maybe useful in TB prevention and control strategies worldwide.

The lateral hypothalamus to lateral habenula projection, but not the ventral pallidum to lateral habenula projection, regulates voluntary ethanol consumption

The lateral habenula (LHb) is an epithalamic brain region implicated in aversive processing via negative modulation of midbrain dopamine (DA) and serotonin (5-HT) systems. Given the role of the LHb in inhibiting DA and 5-HT systems, it is thought to be involved in various psychiatric pathologies, including drug addiction. In support, it has been shown that LHb plays a critical role in cocaine- and ethanol-related behaviors, most likely by mediating drug-induced aversive conditioning. In our previous work, we showed that LHb lesions increased voluntary ethanol consumption and operant ethanol self-administration and blocked yohimbine-induced reinstatement of ethanol self-administration. LHb lesions also attenuated ethanol-induced conditioned taste aversion suggesting that a mechanism for the increased intake of ethanol may be reduced aversion learning. However, whether afferents to the LHb are required for mediating effects of the LHb on these behaviors remained to be investigated. Our present results show that lesioning the fiber bundle carrying afferent inputs to the LHb, the stria medullaris (SM), increases voluntary ethanol consumption, suggesting that afferent structures projecting to the LHb are important for mediating ethanol-directed behaviors. We then chose two afferent structures as the focus of our investigation. We specifically studied the role of the inputs from the lateral hypothalamus (LH) and ventral pallidum (VP) to the LHb in ethanol-directed behaviors. Our results show that the LH-LHb projection is necessary for regulating voluntary ethanol consumption. These results are an important first step towards understanding the functional role of afferents to LHb with regard to ethanol consumption.

Excitation of lateral habenula neurons as a neural mechanism underlying ethanol-induced conditioned taste aversion

KEY POINTS

The lateral habenula (LHb) has been implicated in regulation of drug-seeking behaviours through aversion-mediated learning. In this study, we recorded neuronal activity in the LHb of rats during an operant task before and after ethanol-induced conditioned taste aversion (CTA) to saccharin. Ethanol-induced CTA caused significantly higher baseline firing rates in LHb neurons, as well as elevated firing rates in response to cue presentation, lever press and saccharin taste. In a separate cohort of rats, we found that bilateral LHb lesions blocked ethanol-induced CTA. Our results strongly suggest that excitation of LHb neurons is required for ethanol-induced CTA, and point towards a mechanism through which LHb firing may regulate voluntary ethanol consumption.

ABSTRACT

Ethanol, like other drugs of abuse, has both rewarding and aversive properties. Previous work suggests that sensitivity to ethanol's aversive effects negatively modulates voluntary alcohol intake and thus may be important in vulnerability to developing alcohol use disorders. We previously found that rats with lesions of the lateral habenula (LHb), which is implicated in aversion-mediated learning, show accelerated escalation of voluntary ethanol consumption. To understand neural encoding in the LHb contributing to ethanol-induced aversion, we recorded neural firing in the LHb of freely behaving, water-deprived rats before and after an ethanol-induced (1.5 g kg^-1 20% ethanol, i.p.) conditioned taste aversion (CTA) to saccharin taste. Ethanol-induced CTA strongly decreased motivation for saccharin in an operant task to obtain the tastant. Comparison of LHb neural firing before and after CTA induction revealed four main differences in firing properties. First, baseline firing after CTA induction was significantly higher. Second, firing evoked by cues signalling saccharin availability shifted from a pattern of primarily inhibition before CTA to primarily excitation after CTA induction. Third, CTA induction reduced the magnitude of lever press-evoked inhibition. Finally, firing rates were significantly higher during consumption of the devalued saccharin solution after CTA induction. Next, we studied sham- and LHb-lesioned rats in our operant CTA paradigm and found that LHb lesion significantly attenuated CTA effects in the operant task. Our data demonstrate the importance of LHb excitation in regulating expression of ethanol-induced aversion and suggest a mechanism for its role in modulating escalation of voluntary ethanol intake.

Acute ethanol effects on neural encoding of reward size and delay in the nucleus accumbens

Acute ethanol administration can cause impulsivity, resulting in increased preference for immediately available rewards over delayed but more valuable alternatives. The manner in which reward size and delay are represented in neural firing is not fully understood, and very little is known about ethanol effects on this encoding. To address this issue, we used in vivo electrophysiology to characterize neural firing in the core of the nucleus accumbens (NAcc) in rats responding for rewards that varied in size or delay after vehicle or ethanol administration. The NAcc is a central element in the circuit that governs decision-making and importantly, promotes choice of delayed rewards. We found that NAcc firing in response to reward-predictive cues encoded anticipated reward value after vehicle administration, but ethanol administration disrupted this encoding, resulting in a loss of discrimination between immediate and delayed rewards in cue-evoked neural responses. In addition, NAcc firing occurring at the time of the operant response (lever pressing) was inversely correlated with behavioral response latency, such that increased firing rates were associated with decreased latencies to lever press. Ethanol administration selectively attenuated this lever press-evoked firing when delayed but not immediate rewards were expected. These effects on neural firing were accompanied by increased behavioral latencies to respond for delayed rewards. Our results suggest that ethanol effects on NAcc cue- and lever press-evoked encoding may contribute to ethanol-induced impulsivity.

Lesion of the rostromedial tegmental nucleus increases voluntary ethanol consumption and accelerates extinction of ethanol-induced conditioned taste aversion

RATIONALE

Ethanol has rewarding and aversive properties, and the balance of these properties influences voluntary ethanol consumption. Preclinical and clinical evidence show that the aversive properties of ethanol limit intake. The neural circuits underlying ethanol-induced aversion learning are not fully understood. We have previously shown that the lateral habenula (LHb), a region critical for aversive conditioning, plays an important role in ethanol-directed behaviors. However, the neurocircuitry through which LHb exerts its actions is unknown.

OBJECTIVE

In the present study, we investigate a role for the rostromedial tegmental nucleus (RMTg), a major LHb projection target, in regulating ethanol-directed behaviors.

METHODS

Rats received either sham or RMTg lesions and were studied during voluntary ethanol consumption; operant ethanol self-administration, extinction, and yohimbine-induced reinstatement of ethanol-seeking; and ethanol-induced conditioned taste aversion (CTA).

RESULTS

RMTg lesions increased voluntary ethanol consumption and accelerated extinction of ethanol-induced CTA.

CONCLUSIONS

The RMTg plays an important role in regulating voluntary ethanol consumption, possibly by mediating ethanol-induced aversive conditioning.

Lesions of the lateral habenula increase voluntary ethanol consumption and operant self-administration, block yohimbine-induced reinstatement of ethanol seeking, and attenuate ethanol-induced conditioned taste aversion

The lateral habenula (LHb) plays an important role in learning driven by negative outcomes. Many drugs of abuse, including ethanol, have dose-dependent aversive effects that act to limit intake of the drug. However, the role of the LHb in regulating ethanol intake is unknown. In the present study, we compared voluntary ethanol consumption and self-administration, yohimbine-induced reinstatement of ethanol seeking, and ethanol-induced conditioned taste aversion in rats with sham or LHb lesions. In rats given home cage access to 20% ethanol in an intermittent access two bottle choice paradigm, lesioned animals escalated their voluntary ethanol consumption more rapidly than sham-lesioned control animals and maintained higher stable rates of voluntary ethanol intake. Similarly, lesioned animals exhibited higher rates of responding for ethanol in operant self-administration sessions. In addition, LHb lesion blocked yohimbine-induced reinstatement of ethanol seeking after extinction. Finally, LHb lesion significantly attenuated an ethanol-induced conditioned taste aversion. Our results demonstrate an important role for the LHb in multiple facets of ethanol-directed behavior, and further suggest that the LHb may contribute to ethanol-directed behaviors by mediating learning driven by the aversive effects of the drug.

Mu opioid receptor antagonism in the nucleus accumbens shell blocks consumption of a preferred sucrose solution in an anticipatory contrast paradigm

Binge eating, a central feature of multiple eating disorders, is characterized by excessive consumption occurring during discrete, often brief, intervals. Highly palatable foods play an important role in these binge episodes - foods chosen during bingeing are typically higher in fat or sugar than those normally consumed. Multiple lines of evidence suggest a central role for signaling by endogenous opioids in promoting palatability-driven eating. This role extends to binge-like feeding studied in animal models, which is reduced by administration of opioid antagonists. However, the neural circuits and specific opioid receptors mediating these effects are not fully understood. In the present experiments, we tested the hypothesis that endogenous opioid signaling in the nucleus accumbens promotes consumption in a model of binge eating. We used an anticipatory contrast paradigm in which separate groups of rats were presented sequentially with 4% sucrose and then either 20% or 0% sucrose solutions. In rats presented with 4% and then 20% sucrose, daily training in this paradigm produced robust intake of 20% sucrose, preceded by learned hypophagia during access to 4% sucrose. We tested the effects of site-specific infusions of naltrexone (a nonspecific opioid receptor antagonist: 0, 1, 10, and 50μg/side in the nucleus accumbens core and shell), naltrindole (a delta opioid receptor antagonist: 0, 0.5, 5, and 10μg/side in the nucleus accumbens shell) and beta-funaltrexamine (a mu opioid receptor antagonist: 0 and 2.5μg/side in the nucleus accumbens shell) on consumption in this contrast paradigm. Our results show that signaling through the mu opioid receptor in the nucleus accumbens shell is dynamically modulated during formation of learned food preferences, and promotes binge-like consumption of palatable foods based on these learned preferences.

Invigoration of reward seeking by cue and proximity encoding in the nucleus accumbens

A key function of the nucleus accumbens is to promote vigorous reward seeking, but the corresponding neural mechanism has not been identified despite many years of research. Here, we study cued flexible approach behavior, a form of reward seeking that strongly depends on the accumbens, and we describe a robust, single-cell neural correlate of behavioral vigor in the excitatory response of accumbens neurons to reward-predictive cues. Well before locomotion begins, this cue-evoked excitation predicts both the movement initiation latency and the speed of subsequent flexible approach responses, but not those of stereotyped, inflexible responses. Moreover, the excitation simultaneously signals the subject's proximity to the approach target, a signal that appears to mediate greater response vigor on trials that begin with the subject closer to the target. These results demonstrate a neural mechanism for response invigoration whereby accumbens neuronal encoding of reward availability and target proximity together drive the onset and speed of reward-seeking locomotion.

mu-Opioid receptor stimulation in the nucleus accumbens elevates fatty tastant intake by increasing palatability and suppressing satiety signals

Infusion of a μ-opioid receptor (MOR) agonist into the nucleus accumbens (NAcc) drives voracious food intake, an effect hypothesized to occur through increased tastant palatability. While intake of many palatable foods is elevated by MOR stimulation, this manipulation has a preferential effect on fatty food ingestion. Consumption of high-fat foods is increased by NAcc MOR stimulation even in rats that prefer a carbohydrate-rich alternative under baseline conditions. This suggests that NAcc MOR stimulation may not simply potentiate palatability signals and raises the possibility that mechanisms mediating fat intake may be distinct from those underlying intake of other tastants. The present study was conducted to investigate the physiological mechanisms underlying the effects of NAcc MOR stimulation on fatty food intake. In experiment 1, we analyzed lick microstructure in rats ingesting Intralipid to identify the changes underlying feeding induced by infusion of a MOR-specific agonist into the NAcc. MOR stimulation in the NAcc core, but not shell, increased burst duration and first-minute licks, while simultaneously increasing the rate and duration of Intralipid ingestion. These results suggest that MOR activation in the core increases Intralipid palatability and attenuates inhibitory postingestive feedback. In experiment 2, we measured the effects of MOR stimulation in the NAcc core on consumption of nonnutritive olestra. A MOR-specific agonist dose dependently increased olestra intake, demonstrating that caloric signaling is not required for hyperphagia induced by NAcc MOR stimulation. Feeding induced by drug infusion in both experiments 1 and 2 was blocked by a MOR antagonist. In experiment 3, we determined whether MOR activation in the NAcc core could attenuate satiety-related signaling caused by infusion of the melanocortin agonist MTII into the third ventricle. Suppression of intake caused by MTII was reversed by MOR stimulation. Together, our results suggest that MOR stimulation in the NAcc core elevates fatty food intake through palatability mechanisms dependent on orosensory cues and suppression of satiety signals inhibiting food intake.

Modulation of feeding and locomotion through mu and delta opioid receptor signaling in the nucleus accumbens

Opioid signaling has been strongly implicated in driving palatable food consumption. The nucleus accumbens (NAcc) is one important site of this effect; hyperphagia elicited by administration of exogenous mu opioid receptor (MOR) ligands in this brain region has been well documented. However, the role that endogenous opioid ligands in the NAcc play in controlling food intake remains poorly understood. Enkephalins, which signal through both the MOR and delta opioid receptor (DOR), are highly expressed within a subset of NAcc neurons, and have been shown to be sensitive to manipulations of diet and motivation. To investigate a potential role for these signaling molecules in regulating palatability-driven consumption, we measured high fat chow intake in rats following a series of pharmacological manipulations of NAcc opioid signaling. NAcc infusion of the MOR agonist [D-Ala2, N-MePHe4, Gly-ol]-enkephalin (DAMGO) robustly increased palatable food intake, as has previously been demonstrated. In contrast, neither infusion of Met-enkephalin, its synthetic analogue [D-Ala2] Met-enkephalin (DALA) nor the DOR-specific ligand [D-Pen2, Pen5]-enkephalin (DPDPE) had significant effects on food intake. However, when administered in combination with DAMGO, DPDPE significantly suppressed the magnitude of DAMGO-evoked feeding. Further analysis of DPDPE effects revealed that the drug strongly increased locomotor activity. Suppressive effects on feeding, then, may have occurred through competition between feeding and locomotion for behavioral expression.

Preference or fat? Revisiting opioid effects on food intake

It is well established that opioid signaling in the central nervous system constitutes a powerful stimulus for food intake. The role of opioids in determining food preference, however, is less well defined. Opioids have been proposed to promote intake of preferred foods, or, alternatively, to preferentially increase consumption of fat. In the present manuscript, I comprehensively review results from previous studies investigating this issue. Data from these studies suggests a mechanism for opioid action that may reconcile the previously proposed hypotheses: opioid effects on food intake do appear to be largely specific for fat consumption, but individual animals' sensitivity to this effect may be dependent on baseline food preferences. In addition, I highlight the possibility that the selectivity of endogenous opioid effects may importantly differ from that of exogenous agonists in the degree to which baseline preferences, rather than macronutrient intake, are altered. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.

Convergent, not serial, striatal and pallidal circuits regulate opioid-induced food intake

Mu opioid receptor (MOR) signaling in the nucleus accumbens (NAcc) elicits marked increases in the consumption of palatable tastants. However, the mechanism and circuitry underlying this effect are not fully understood. Multiple downstream target regions have been implicated in mediating this effect but the role of the ventral pallidum (VP), a primary target of NAcc efferents, has not been well defined. To probe the mechanisms underlying increased consumption, we identified behavioral changes in rats' licking patterns following NAcc MOR stimulation. Because the temporal structure of licking reflects the physiological substrates modulating consumption, these measures provide a useful tool in dissecting the cause of increased consumption following NAcc MOR stimulation. Next, we used a combination of pharmacological inactivation and lesions to define the role of the VP in hyperphagia following infusion of the MOR-specific agonist [D-Ala2, N-MePhe4, Gly-ol]-enkephalin (DAMGO) into the NAcc. In agreement with previous studies, results from lick microstructure analysis suggest that NAcc MOR stimulation augments intake through a palatability-driven mechanism. Our results also demonstrate an important role for the VP in normal feeding behavior: pharmacological inactivation of the VP suppresses baseline and NAcc DAMGO-induced consumption. However, this interaction does not occur through a serial circuit requiring direct projections from the NAcc to the VP. Rather, our results indicate that NAcc and VP circuits converge on a common downstream target that regulates food intake.

Inhibition of orexin-1/hypocretin-1 receptors inhibits yohimbine-induced reinstatement of ethanol and sucrose seeking in Long-Evans rats

RATIONALE

Previous studies have shown that orexin-1/hypocretin-1 receptors play a role in self-administration and cue-induced reinstatement of food, drug, and ethanol seeking. In the current study, we examined the role of orexin-1/hypocretin-1 receptors in operant self-administration of ethanol and sucrose and in yohimbine-induced reinstatement of ethanol and sucrose seeking.

MATERIALS AND METHODS

Rats were trained to self-administer either 10% ethanol or 5% sucrose (30 min/day). The orexin-1 receptor antagonist SB334867 (0, 5, 10, 15, 20 mg/kg, i.p.) was administered 30 min before the operant self-administration sessions. After these experiments, the operant self-administration behaviors were extinguished in both the ethanol and sucrose-trained rats. Upon reaching extinction criteria, SB334867 (0, 5, 10 mg/kg, i.p.) was administered 30 min before yohimbine (0 or 2 mg/kg, i.p.). In a separate experiment, the effect of SB334867 (0, 15, or 20 mg/kg, i.p.) on general locomotor activity was determined using the open-field test.

RESULTS

The orexin-1 receptor antagonist, SB334867 (10, 15 and 20 mg/kg) decreased operant self-administration of 10% ethanol but not 5% sucrose self-administration. Furthermore, SB334867 (5 and 10 mg/kg) significantly decreased yohimbine-induced reinstatement of both ethanol and sucrose seeking. SB334867 did not significantly affect locomotor activity measured using the open-field test.

CONCLUSIONS

The results suggest that inhibition of OX-1/Hcrt-1 receptors modulates operant ethanol self-administration and also plays a significant role in yohimbine-induced reinstatement of both ethanol and sucrose seeking in rats.

Cue-evoked encoding of movement planning and execution in the rat nucleus accumbens

The nucleus accumbens is involved in the modulation of motivated behaviour by reward-associated sensory information. However, little is known about the specific nature of the nucleus accumbens' contribution to generating movement. We investigated motor encoding by nucleus accumbens neurons in rats performing a delayed response task that allowed us to dissociate the effects of sensory and motor events on firing. In a subset of neurons, firing in the delay period preceding movement was highly selective; this selectivity was tightly correlated with the direction of the subsequent movement, but not with the sensory properties of the instructive cue. Direction selectivity in this population of neurons developed over the course of the delay period, with the strongest selectivity apparent just prior to movement onset. Selectivity was also apparent in nucleus accumbens neurons during movement, such that firing showed a tight correlation with movement direction, but not the instructive cue presented nor the spatial destination of the movement. These results are consistent with the hypothesis that a subpopulation of nucleus accumbens neurons contributes to the selection and execution of specific motivated behaviours.

Nucleus accumbens opioid signaling conditions short-term flavor preferences

Opioid signaling in the nucleus accumbens (NAcc) strongly modulates flavor-based food choice. To further investigate the role of opioid signaling in taste reward, we used a sensory specific satiety (SSS) paradigm to devalue specific flavors of nutritionally identical food pellets in rats. In the NAcc, infusion of a mu opioid (MOP) receptor selective agonist selectively increased consumption of a pre-fed flavor, thus reversing the SSS effect. Conversely, blockade of endogenous opioid signaling with the opioid antagonist naltrexone selectively decreased consumption of a recently consumed flavor, potentiating the SSS effect. No enhancement of consumption was observed if a delay of 3 h was imposed following the intra-NAcc MOP agonist indicating that there were no long-term changes in flavor preference. If a delay was introduced between the initial flavor exposure and the intra-NAcc MOP agonist infusion, pellet consumption was increased non-selectively (irrespective of flavor) suggesting that close temporal contiguity between flavor experience and NAcc opioid action is critical for the opioid effect on flavor preference. In contrast to opioid effects, inactivating NAcc neurons by local microinjection of muscimol (a GABAA agonist) increased consumption of both the pre-fed and non-pre-fed flavors equally. These results demonstrate that opioids released in the NAcc during consumption of palatable foods produce a selective and transient increase in preference for a recently sampled flavor.

Endogenous opioids encode relative taste preference

Endogenous opioid signaling contributes to the neural control of food intake. Opioid signaling is thought to regulate palatability, the reward value of a food item as determined by orosensory cues such as taste and texture. The reward value of a food reflects not only these sensory properties but also the relative value of competing food choices. In the present experiment, we used a consummatory contrast paradigm to manipulate the relative value of a sucrose solution for two groups of rats. Systemic injection of the nonspecific opioid antagonist naltrexone suppressed sucrose intake; for both groups, however, this suppression was selective, occurring only for the relatively more valuable sucrose solution. Our results indicate that endogenous opioid signaling contributes to the encoding of relative reward value.

Orexin A in the VTA is critical for the induction of synaptic plasticity and behavioral sensitization to cocaine

Dopamine neurons in the ventral tegmental area (VTA) represent a critical site of synaptic plasticity induced by addictive drugs. Orexin/hypocretin-containing neurons in the lateral hypothalamus project to the VTA, and behavioral studies have suggested that orexin neurons play an important role in motivation, feeding, and adaptive behaviors. However, the role of orexin signaling in neural plasticity is poorly understood. The present study shows that in vitro application of orexin A induces potentiation of N-methyl-D-aspartate receptor (NMDAR)-mediated neurotransmission via a PLC/PKC-dependent insertion of NMDARs in VTA dopamine neuron synapses. Furthermore, in vivo administration of an orexin 1 receptor antagonist blocks locomotor sensitization to cocaine and occludes cocaine-induced potentiation of excitatory currents in VTA dopamine neurons. These results provide in vitro and in vivo evidence for a critical role of orexin signaling in the VTA in neural plasticity relevant to addiction.

Inhibitions of nucleus accumbens neurons encode a gating signal for reward-directed behavior

The nucleus accumbens (NAcc) is critical in the control of goal-directed behavior. Pharmacological studies suggest that the NAcc may act in both instructive and permissive modes; however, previous electrophysiological studies in behaving rats have reported firing patterns consistent with an instructive, but not permissive, role for NAcc neurons. We now report that a subset of NAcc neurons shows a long-lasting inhibition in firing rate whose onset precedes initiation of goal-directed sequences of behavior and terminates at the conclusion of the sequence. Together with data from previous behavioral studies, this firing pattern suggests that, when active, these neurons tonically inhibit appetitive and consummatory behaviors and that, when inhibited, these neurons permissively gate those behaviors.

Ocular dominance plasticity is stably maintained in the absence of alpha calcium calmodulin kinase II (alphaCaMKII) autophosphorylation

The molecule alpha calcium calmodulin kinase II (alphaCaMKII) is known to play a fundamental role in the induction of many forms of synaptic plasticity. A major theory of alphaCaMKII function proposes that autophosphorylation of the molecule mediates not only the induction but also the maintenance of synaptic plasticity. To test this hypothesis, we assessed ocular dominance plasticity in genetically engineered mice that carry a mutation preventing autophosphorylation of alphaCaMKII. These mutant mice are deficient in plasticity after monocular deprivation, but a sufficiently long period of monocular deprivation will induce ocular dominance plasticity. After induction of ocular dominance plasticity, the stability of the induced changes was assayed after binocular deprivation. Plasticity in homozygous mutant animals was as stable as that measured in WT littermates; also, response characteristics did not differ between the two groups. Our results suggest that alphaCaMKII autophosphorylation is required for the induction of ocular dominance plasticity but is not needed for its stable maintenance thereafter.

Encoding of palatability and appetitive behaviors by distinct neuronal populations in the nucleus accumbens

Obesity is a major public health problem. Palatability (i.e., the reinforcing value of food, derived from orosensory cues) is a significant factor in determining food intake and contributes to increased consumption leading to obesity. The nucleus accumbens is a ventral striatal region that is important for both appetitive and consummatory behaviors and has been implicated in modulating palatability. In this study, we investigated palatability encoding in the firing of nucleus accumbens neurons in rats. Nucleus accumbens neurons with significant changes in firing rate during consummatory behavior displayed one of two principal firing patterns. Firing in one class of nucleus accumbens neurons was correlated with the palatability of sucrose reinforcers; changes in neural activity in this class consisted primarily of excitations. Within this group of neurons, a subset was sensitive to the relative value of sucrose reinforcers, as assessed by a behavioral contrast paradigm. A second and distinct population of nucleus accumbens neurons, with changes in firing that were pre-dominantly inhibitions, was not sensitive to reinforcer palatability; rather, these inhibitions were present even during unreinforced bouts of licking. In addition, the onset of these inhibitions typically occurred before the initiation of the licking behavior itself. We propose that two primary classes of nucleus accumbens neurons contribute to neural processing immediately before and during reinforcer consumption: inhibitions related to initiation and maintenance of consummatory behaviors and excitations that encode reinforcer palatability.

Molecular substrates of plasticity in the developing visual cortex

Ocular dominance plasticity may be the paradigmatic in vivo model of activity-dependent plasticity. More than four decades of intense research has delineated the network-level rules that govern synaptic change in this model. The recent characterization of a murine model for ocular dominance plasticity has facilitated rapid progress on a new front, extending our understanding of the molecular mechanisms underlying ocular dominance plasticity. In this review, we highlight recent advances in this research effort, focusing in particular on signaling pathways mediating shifts in ocular dominance, and mechanisms underlying the timing of the critical period.

Nucleus accumbens dopamine release is necessary and sufficient to promote the behavioral response to reward-predictive cues

The nucleus accumbens is part of the neural circuit that controls reward-seeking in response to reward-predictive cues. Dopamine release in the accumbens is essential for the normal functioning of this circuit. Previous studies have shown that injection of dopamine receptor antagonists into the accumbens severely impairs an animal's ability to perform operant behaviors specified by predictive cues. Furthermore, excitations and inhibitions of accumbens neurons evoked by such cues are abolished by inactivation of the ventral tegmental area, the major dopaminergic input to the accumbens. These results indicate that dopamine is necessary to elicit neural activity in the accumbens that drives the behavioral response to cues. Here we show that accumbens dopamine release is causal to the rats' reward-seeking behavioral response by demonstrating that dopamine in this structure is both necessary and sufficient to promote the appropriate behavioral response to reward-predictive cues.

Physicians' knowledge, attitude and practice towards erectile dysfunction in Saudi Arabia

We aimed to test the knowledge, attitude and practice (KAP) of physicians towards erectile dysfunction in the Eastern province of Saudi Arabia. At a scientific meeting about erectile dysfunction, 159 physicians from both government and private sectors answered a 34-item questionnaire in private. The mean total KAP score for the group was below the expected standard of 60%. Male physicians scored significantly higher than females. Urologists scored the highest, followed by andrologists. Surprisingly, physicians with higher qualifications scored lower than those with intermediate qualifications and even less than general practitioners. Those who had practised for > or = 10 years scored better than those with < 10 years practice. The role of cardiologists in the diagnosis and management of erectile dysfunction is discussed.

Urethral calculi: presentation and management

OBJECTIVE

To determine the occurrence, symptoms, treatment and outcome in patients with urethral stones.

PATIENTS AND METHODS

Fifty-one consecutive patients with urethral calculi were assessed prospectively; all were male and one was an infant.

RESULTS

Acute retention of urine occurred in 78% of patients, urethral anatomical pathology in 6% and posterior urethral calculi in 88%. The urethral stones, solitary in each patient, consisted of calcium oxalate in 86%, struvite in 6%, mixed stones in 4%, calcium phosphate in 2% and uric acid in 2%. A methodical approach to therapy was used which aimed to clearly define the circumstances in which a given procedure was used, and the resulting success rate.

CONCLUSION

The common belief that most urethral calculi in patients in developing countries originate from the bladder does not seem to be generally applicable. Urethral anatomical pathology does not seem to be a necessary condition for most of these calculi.

Ecological factors underlying protein-calorie malnutrition in an irrigated area of the Sudan

A community survey was undertaken in 14 villages in the Gezira farming region of the Sudan to determine the causes of malnutrition which is prevalent in the area. Low expenditure on food, poor housing conditions, and poor hygiene were found to result from low income. While the ultimate goal should be improvement of income, quicker results will accrue from tackling the equally important dietary causes which result from ignorance about child feeding. In the Sudan, the decline of breastfeeding, the rise in bottlefeeding, the lack of supplementary feeding, and inequitable intrafamily distribution of food are particularly important causative factors. The low levels of immunization against communicable diseases is a contributory factor which could be corrected immediately. Family size and birth rank were not important in the etiology of malnutrition.

Anterior hypospadias. Is repair necessary with urination in a sitting or squatting position?

OBJECTIVE

To determine the chronic complication rate of anterior hypospadias repair and to explore whether the practice of placing the neomeatus at the tip of the penis should be applicable to all cases in our community where urination is in a sitting/squatting position.

METHODS

Over a 10-year period commencing 1st September 1987, 312 patients had hypospadias repair of whom 72% had anterior hypospadias. The meatus was advanced to the tip of the penis in all repairs. The location of the meatus was also determined in 281 non-complaining men with a straight penis and normal sexual and reproductive functions. Following prior information that anterior hypospadias was not associated with sexual and reproductive dysfunction, 51 patients were given a choice between repair or no repair.

RESULTS

Urethrocutaneous fistula occurred in 5% of patients, urethral stricture in 3% and meatal retraction in 3%, with 92% of patients having no complications. Forty six percent of non-complaining men had the meatus in locations other than the tip of the penis. Of 51 patients with the benefit of informed consent, 73% opted for no repair.

CONCLUSION

Our results of anterior hypospadias repair compare favourably with those of other centers. Placement of the meatus at the tip of the penis for anterior hypospadias should not be applicable to all patients in this community where urination is in a sitting/squatting position. Before such repairs, an informed consent is warranted by making the patients and their parents aware of the non-association of sexual and reproductive disorders with these anomalies.

Unusual high presentation of torsion of testicular appendages

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Effect of ambrein on smooth muscle responses to various agonists

The pharmacological effects of ambrein (isolated from ambergris) on the contractile responses induced by some agonists in smooth muscle preparations were investigated. Ambrein in the concentration range of 10, 50 and 250 microg/ml decreased the spontaneous contraction of the isolated rabbit jejunum, rat uterus and guinea-pig vas deferens. Ambrein-induced antagonism to acetylcholine (Ach) in the guinea-pig ileum was abolished when the concentration of calcium chloride in the Tyrode's solution was increased to 5 mM/l. Furthermore, ambrein did not antagonise nicotine-induced contractions in the isolated rabbit jejunum or serotonin-induced contractions in the isolated guinea-pig ileum and vas deferens or the rat uterus. However, ambrein in the concentration range of 10, 50 and 250 microg/ml antagonised prostaglandins (PGs) E2, D2, F2alpha, and oxytocin-induced contractions in the rat uterus in vitro. Ambrein also antagonised (+/-) noradrenaline and (-) adrenaline-induced contractions in the isolated guinea-pig vas deferens. It is concluded that ambrein-induced non-selective dose-dependent antagonism to the effects of some agonists (Ach, adrenaline, noradrenaline, PGs and oxytocin) in some smooth muscles may be due to the ability of this compound to interfere with the mobilisation of extracellular Ca2+ required for muscular contractions induced by these agonists.

Hypoglycemic effect and protein nutritive quality of soy and methionine-supplemented whole durum pasta products

New low cost, high-protein and high-fiber pasta products processed from whole durum meal (WD) solely, WD supplemented with 7% or 12% defatted soy flour (SF), or 12% SF plus 0.3% methionine were evaluated in comparison with the regular pasta made of pure durum semolina (DS). Their protein nutritive quality was biologically evaluated by rat growth studies using diets containing 9% protein, through the parameters: food efficiency ratio (FER), protein efficiency ratio (PER), net protein utilization (NPU), digestibility coefficient (DC) and biological value (BV). The original products were administered to diabetic hypercholesterolemic albino rats, (injected with alloxane) to study their effects on the levels of blood glucose and plasma lipid fractions. The results indicate that diets based on pasta made of WD supplemented with SE or SF plus methionine had superior protein quality and succeeded in supporting normal growth of rats in contrast to the diets based on pasta made of unsupplemented WD or DS. These assays demonstrated that the values of FER, PER, NPU and BV of WD-pasta increased with increasing SF supplementation. However, high-fiber pasta made of unrefined WD solely or with SF had lower DC values compared to that of the regular DS-pasta. DC values decreased as the added SF increased. Adding methionine evidently affected FER, PER, BV and NPU values. Administration of high-protein and high-fiber pasta samples made of WD solely, supplemented with SF or SF plus methionine significantly reduced the elevated blood glucose as well as plasma cholesterol and plasma lipid fractions in hypercholesterolemic diabetic rats. Overall, considering nutritional evaluation, protein cost as well as hypoglycemic and hypocholesterolemic effects the pasta composed of 12% SF-WD and supplemented with 0.3% methionine represented the best high-fiber; high-protein and high-quality product.

Protection by epicoprostanol against hyperglycemia and insulitis in normal and diabetic rats

Epicoprostanol (3-alpha-hydroxy-5 beta-cholestanol) has been studied for its effects on blood glucose and plasma insulin levels in rodents. Epicoprostanol significantly induced hypoglycemia and increased insulin levels in rat blood plasma by 88% and 66% compared to that of control after 2 h and 4 h of acute treatment at 100 mg/kg dose. It also highly significantly lowered blood glucose levels in a dose dependent manner at 50, 100 and 200 mg/kg doses when administered to alloxan-rendered moderately diabetic rats after 120 and 240 min of treatment. Similarly, epicoprostanol, with the same dosage regimen, caused hypoglycemia in streptozotocin-induced severe diabetic rats, to a similar extent at the same time-points. However, the lowest dose (10 mg/kg) failed to produce a striking effect in either of the diabetic groups. In normoglycemic rats, plasma insulin levels were affected significantly after a single dose (100 mg/kg) of epicoprostanol. In contrast, diabetic animals suffering from insulitis showed a significant decline in hyperglycemia, strongly suggesting an insulin-like action of epicoprostanol. It seems likely that epicoprostanol acts through a mechanism other than hyperinsulinemia.

Effect of (-)-cathinone, a psychoactive alkaloid from khat (Catha edulis Forsk.) and caffeine on sexual behaviour in rats

The effect of (-)-cathinone, caffeine and their combinations was studied on the sexual behaviour of male rats. Male sexual activities were assessed by recording the erectile responses (grooming of genitalis, yawning/stretching and homosexual mounting), in the absence of females. The copulatory behaviour was observed by caging males with receptive females brought into oestrus with s.c. injection of oestradiol benzoate and progesterone. The copulatory pattern of male rats (mounting, intromissions, ejaculations and refractory period) was recorded. The oral treatment of cathinone (5 mg kg-1 day-1), caffeine (50 mg kg-1 day-1) and their combinations for 15 days increased arousal (motivation) in male rats as evidenced by increased mounting performance and anogenital investigatory behaviour. However, erectile and ejaculatory responses, measured in the present study, showed no stimulant effect. It is conceivable from the present results that cathinone, the psychostimulant constituent of khat modified masculine pattern behaviour and caffeine also changed the effect of cathinone when administered concomitantly. However, our data provide no evidence that cathinone could be considered as an aphrodisiac.

A study of ambrein treatment for the evaluation of change in plasma biochemical parameters in rats

Biochemical effects of acute and subacute treatments with ambrein were investigated in rats by measuring the total proteins, cholesterol, triglycerides, GOT, GPT and alkaline phosphatase in the blood plasma. Also, determinations of prothrombin time (PT), partial thrombin time (PTT), thrombin time (TT) and fibrinogen level were performed. Furthermore, changes in plasma electrolyte concentration were studied. Ambrein administered i.p. did not cause any toxic symptoms in the liver as revealed by the histology of the liver tissue both in acute and subacute treatments. Ambrein itself did not significantly affect the plasma protein, cholesterol, GOT and GPT profiles, but lowered alkaline phosphatase at high doses (50 and 250 mg/kg) after subacute treatment. Thus far, no specific pattern of action of ambrein in electrolyte control has been found. However, it increased PT, PTT and TT and decreased fibrinogen levels in both the acute and subacute studies, pointing towards its potential as an anticoagulant and antifibrinogenic agent.

Effect of ambrein, a major constituent of ambergris, on masculine sexual behavior in rats

The effect of ambrein, a major constituent of ambergris, was studied on the sexual behavior of male rats. The rats were administered ambrein in doses of 100 and 300 mg/kg body weight. Male sexual activities were assessed by recording the erectile responses (penile erection) and homosexual mountings in the absence of female. The copulatory studies were carried out by caging males with receptive females brought into estrus with subcutaneous injections of estradiol benzoate and progesterone. The copulatory pattern of treated male rats (mountings, intromissions, ejaculations and refractory period), the pendiculations (yawns/stretches) and orientation activities towards females, the environment and themselves, were recorded. Ambrein produced recurrent episodes of penile erection, a dose-dependent, vigorous and repetitive increase in intromissions and an increased anogenital investigatory behavior, identifying the drug used in the present study as a sexual stimulant. It is conceivable from the present results that the ambrein-modified masculine sexual behavior in male rats supports the folk use of this drug as an aphrodisiac.

Laboratory induced resistance to praziquantel in experimental schistosomiasis

To study the effect of praziquantel (PZQ) on successive generations of S. mansoni worms, infected mice were treated 6 weeks after infection with different doses of PZQ (300, 500 mg/kg.), the schistosome strain was originally obtained from an infected Egyptian patient. The eggs subsequently produced by worms that had survived the PZQ treatment were used to infect snails and mice of the following generations. The results were expressed as average number of worms and cure rates in comparison with control groups. It was found that the use of PZQ., especially in low subcurative dose may lead to the development of resistance to therapeutic dose of the drug in following generations.

Male pseudohermaphroditism: factors determining the gender of rearing in Saudi Arabia

OBJECTIVE

Experience with male pseudohermaphrodites at King Fahd Hospital of King Faisal University, Al-Khobar, Saudi Arabia from 1981 to 1991 was reviewed to ascertain the factors determining the gender of rearing.

METHODS

The records of 14 patients consisting of 6 prepubertal and 8 postpubertal patients were studied. None of the patients had any prior evaluation or treatment, since their gender assignment at birth was carried out by midwives in rural communities. The males presented to our hospital with ambiguous genitalia: small phallus, bifid scrotum, perineoscrotal hypospadias, and undescended testes (UDT). Most of those raised as females presented in the postpubertal period seeking remedy for deep voice, excessive musculature, facial hair, erection of the phallus, ejaculation, inappropriate attraction to the female sex, and primary amenorrhea. As their male genotype became determined, all the patients and/or their parents, with the exception of one, insisted on appropriate reconstructive surgery to the male gender. This report focuses primarily on 11 patients assigned a female gender at birth, 10 of whom insisted on a gender change.

RESULTS

Most adolescents and adults still complained of small penises after reconstructive surgery, but cherished their male role.

CONCLUSIONS

The male genotype is a more important factor than phallic adequacy in determining the gender of rearing in the Kingdom of Saudi Arabia, an observation attributable to the financial, social, and cultural benefits that the male gender confers in Saudi society.

Experimental schistomiasis: the effect of chemotherapy on concomitant immunity and resistance to reinfection

To study the effect of chemotherapy on concomitant immunity, mice infected with Schistosoma mansoni were treated after either 8 or 16 weeks of primary infection and challnged at different periods after treatment. Results were compared with infected un-treated groups of mice. It was found that in mice treated 8 weeks after infection the degree of protection decreased gradually with time and 16 weeks after treatment no significant degree of protection was obtained. On the other hand, mice infected for 16 weeks prior to treatment showed higher degrees of protection and there was still significant degree of resistance to challenge infection after 16 weeks of treatment. It was concluded that in schistosomiasis mansoni there is a certain degree of resistance to reinfection after successful treatment of primary infection prior to treatment.

Studies on the mode of action of ambrein as a new antinociceptive compound

The compound ambrein was isolated from ambergris, which is commonly used as an analgesic in the Saudi folklore medicine. The LD50 of ambrein, given intraperitoneally (i.p.) in mice, was found to be high (7.5 g/kg), and ambrein proved to be a safe compound in this species. In the hotplate test, ambrein was found to possess antinociceptive activity in mice at doses which did not sedate or incapacitate the animals. By the i.p. administration route, ambrein produced antinociception in mice at a dose as low as 10 mg/kg. The antinociceptive activity of ambrein (250 mg/kg i.p.) was inhibited by a noradrenergic neurotoxin (DSP-4) and by naloxone, methysergide or prazosin. It was not influenced by a serotonin depletor, p-chlorophenylalanine. The possible mechanism of ambrein antinociception is discussed.

Rectus andominis myocutaneous flap: Analysis of 40 cases

We present a series of 40 cases who underwent reconstructive procedures using rectus abdominis myocutaneous units. The transplanted tissue comprised superior pedicle (26 cases), inferior pedicle (11 cases), and as free muscle flap (3 cases). The application fell into three groups i.e.; 1. breast and chest wall reconstruction; 2. groin, genital, and trochanteric area; and 3. leg and heel ulcer. The results show that surgical dissection of flaps is relatively easy and has a wide range of applications that can be used for different surgical reconstructive problems. Surgical dissection has a low incidence of complication for flap viability as well as for donor site.

Risk factors in wound infection following urologic operations: a prospective study

A total of 134 urologic operations were studied prospectively for postoperative wound infection, the methodology involving direct intraoperative swab taking. Patients' variables were (mean +/- SD): age 32.4 +/- 20.7 years, Quetelet index 27.4 +/- 8, duration of operation 98 +/- 34 minutes, and male:female ratio 9.3:1. Of the 131 intraoperative swabs 28 (21%) were positive, 97% of the organisms being aerobic; 16% of the patients were nasal carriers of S. aureus. The overall wound infection rate was 9%, and it prolonged hospital stay by six days average. Significant risk factors (and their magnitude) were: age over 60 years (x 2.2), prolonged preoperative hospital stay (x 15), and wound contamination (x 4.3 and x 14.3 for classes 3 and 4 wounds respectively). Neither diabetes mellitus, obesity, nor surgeon's rank was contributory. We conclude that, although the 9% rate of postoperative wound infection was acceptable, appropriate prophylactic antibiotics may reduce it further, and, from our data, we would recommend an aminoglycoside (e.g. Amikacin) and Ampicillin combined.

Management of an unusually high postpubertal presentation of cryptorchidism

A high proportion (43%) of postpubertal presentation of cryptorchid testes was found in 114 patients with undescended testes (UDT). Bilateral presentation of UDT was observed in 25% of patients. Orchiopexy was performed on 75% of postpubertal cases, the determinant factor for choice of operation being cosmetic and psychological. Follow-up results appear to be promising in this environment with very low incidence of testicular cancer.

Chemical investigation of the internal secretion of the sperm blue whale

Ambergris, which is an internal secretion of the sperm blue whale, was extracted with 96% ethanol. The saponified and unsapondied portions have been studied in detail. The number of fractions and components of the unsaponified matter as separated by column and thin layer Chromatography confirm the presence of ambrein (triterpenoid) as well as same other steroid. The saponified portion is reported to contain stearic, oleic, linoleic, archidic and betenic acids. More than one compound have been found in each fraction.

Prognosis of radiologically non-functioning obstructed kidneys

Twenty patients found to have unilateral radiologically non-functioning obstructed kidneys on excretory urography (IVU), and who had normal contralateral kidneys, were further evaluated. Ultrasonography, radionuclide imaging and CT scan were carried out pre-operatively to try to predict which of the kidneys were potentially recoverable after relief of obstruction. Percutaneous nephrostomy was also performed on the last consecutive 7 patients 4 weeks before definitive treatment and the function of the kidneys determined daily. The patients were re-evaluated 2 months after the relief of obstruction. Ultrasonography, radionuclide imaging and CT scan were not found to be reliable in predicting whether these kidneys were potentially recoverable. We consider percutaneous nephrostomy a good procedure for obtaining prognostic information prior to definitive surgery.

Psychological aspects of intersex in Saudi patients

Four cases of male pseudo-hermaphrodism were seen post pubertal. All had been reared as females unambiguously since birth. Two cases developed male gender identity post pubertal, but failed to declare themselves to their families and society until a similar case had been publicized in the local newspaper. The third case did not reveal her problem to her family even after being informed by a doctor at the age of 15, and was discovered accidentally at the age of 22 on routine medical examination. The fourth was discovered accidentally at age 40 after having been married and divorced. The families of the four cases shared a strong desire for their children to be reassigned to the male sex including the third case, irrespective of being assured of her female gender identity by physicians. Psychiatric and social problems encountered pre- and post-operatively are discussed with particular emphasis on the role of culture and traditions.

Fracture of the penis: surgical management

Fracture of the penis is a rare injury, only 135 patients having been reported by 1985. Our recent experience with six patients who underwent emergency surgery, has been documented. The results of treatment were excellent with complete recovery of function. The study recommends operative management as the treatment of choice.