The impact of rounds with a psychiatry team in the intensive care unit: A prospective observational pilot study evaluating the effects on delirium incidence and outcomes

BACKGROUND

Delirium in the intensive care unit (ICU) is a common but serious condition that has been associated with in-hospital mortality and post-discharge psychological dysfunction. The aim of this before and after study is to determine the effect of a multidisciplinary care model entailing daily ICU rounds with a psychiatrist on the incidence of delirium and clinical outcomes.

OBJECTIVE

To assess the impact of a proactive psychiatry consultation model in the surgical ICU on the incidence and duration of delirium.

METHODS

This was a prospective, single institution, observational controlled cohort pilot study of adult patients admitted to a surgical ICU. A control group that received standard of care (SOC) with daily delirium prevention care bundles in the pre-intervention period was compared to an intervention group, which had a psychiatrist participate in daily ICU rounds (post-intervention period). The primary outcome was delirium incidence. The secondary outcomes were: delirium duration, ventilator days, hospital and ICU length of stay, and in-hospital mortality.

RESULTS

A total of 104 patients were enrolled and equally split between SOC and intervention groups; 95 contributed to analysis. The overall incidence of ICU delirium was 19%. SOC and intervention groups had similar rates of delirium (21% vs 18%, p = 0.72). None of the secondary outcomes statistically significantly differed between the two groups.

CONCLUSION

Delirium in ICU patients is a potentially preventable condition with serious sequelae. There was no difference in delirium incidence or duration between patients receiving SOC or patients who had multidisciplinary rounds with a psychiatrist.

Longitudinal patterns of sexual recidivism by age over a 25-year follow-up in California

This study followed 146 sexual offenders released from prison custody for a period of 25-years. Overall, 34% of individuals committed at least one sexual reoffense in the 25 years following release from incarceration. Most sexual recidivism occured within the first 15-years following release. The highest rates of sexual recidivism were observed for individuals under 34 years at release from incarceration, for whom recidivism steadily increased over time before peaking at 42% at 25 years. The mean age at reoffense was 42.51. Age was significantly associated with sexual recidivism at 5 years, but not at subsequent follow-up periods. These findings suggest that long-term patterns of sexual recidivism may be related to age at release. It will be important for future research to explore the characteristics of individuals who commit sexual offenses that may contribute to reoffending risk, and examine the effectiveness of policies and practices designed to mitigate recidivism.

Linking Mental Disorder and Risk in Sexually Violent Person Assessments

A common criticism of sexually violent person (SVP) laws is that psychiatric commitment has been co-opted to continue the incarceration of dangerous criminals, not dangerous individuals with mental illness. This opinion may have credence because some forensic clinicians use a "silo" approach (i.e., diagnosing based on historical criminal behavior rather than current symptomatology, and formulating risk for future sexual violence based on actuarial scores rather than characteristics and features of the mental condition). A silo process fosters a missing link; namely, the absence of a nexus between the mental condition and risk. This approach violates the necessary predicate for involuntary civil commitment, that the symptoms of an individual's current mental disorder be linked to and support a present sexual danger to others. In this article, we provide a brief overview of SVP statutes; describe how the silo approach compromises accurate diagnosis and identification of relevant risk factors; and present actual and fictitious cases illustrating the presence and absence of the missing link.

End-of-life mental health assessments for older aged, medically ill persons with expressed desire to die

In recent years, assisted suicide has been legalized in four states for those who are terminally ill and wish to end their lives with the assistance of lethal doses of medications prescribed by a physician. The ethics-related and legal questions raised by end-of-life suicide and decisional capacity to refuse treatment assessments are complex. In treating patients with end-stage medical conditions or disorders that severely affect the future quality of their lives, clinicians tend to engage in suicide prevention at all costs. Overriding the patient's expressed desire to die conflicts with another value, however, that of the individual's right to autonomy. We provide a framework for understanding these difficult decisions, by providing a review of the epidemiology of suicide in later life; reviewing findings from a unique dataset of suicides among the elderly obtained from the Los Angeles County Coroner's Office, as well as data from states with legalized assisted suicide; presenting a discussion of the two frameworks of suicidal ideation as a pathological versus an existential reaction; and giving a case example that highlights the dilemmas faced by clinicians addressing decisional capacity to refuse treatment in an elderly, medically ill patient who has expressed the wish to die.

Critical concerns in Iraq/Afghanistan war veteran-forensic interface: combat-related postdeployment criminal violence

Identifying whether there is a nexus between Iraq and Afghanistan combat injuries and civilian violence on return from deployment is complicated by differences in reactions of individuals to combat exposure, the overlapping effects of traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD), and the low base rate of civilian violence after combat exposure. Moreover, the overall prevalence of violence among returning Iraq and Afghanistan combat war veterans has not been well documented. Malingered symptoms and either exaggeration or outright fabrication of war zone exposure are challenges to rendering forensic opinions, with the risk reduced by accessing military documents that corroborate war zone duties and exposure. This article serves as a first step toward understanding what may potentiate violence among returning Iraq and Afghanistan veterans. We offer a systematic approach toward the purpose of forensic case formulation that addresses whether combat duty/war zone exposure and associated clinical conditions are linked to criminal violence on return to civilian life.

Critical concerns in Iraq/Afghanistan war veteran-forensic interface: veterans treatment court as diversion in rural communities

The veteran-forensic interface is an emerging area of relevance to forensic clinicians assessing or treating returning Iraq and Afghanistan war veterans facing criminal sanctions. Veterans' Treatment Court (VTC) represents a recent diversion mechanism for low-level offenses that is based on a collaborative justice model. Thirty-nine percent of veterans who served in Iraq or Afghanistan and receiving VA services reside in rural areas. Rural veterans facing criminal justice charges may be at a disadvantage due to limited access to forensic psychiatrists with relevant expertise in providing veterans services for diversion. Therefore, widening the pool of forensic clinicians who have such expertise, as well as knowledge of the signature wounds of the wars as related to aggression and reckless behavior is necessary. This article presents an overview of VTCs and discusses the role of forensic clinicians as stakeholders in this process.

An Australian Brain Bank: a critical investment with a high return!

Research into neuropsychiatric disorders, including alcohol-related problems, is limited in part by the lack of appropriate animal models. However, the development of new technologies in pathology and molecular biology means that many more questions can be addressed using appropriately stored human brain tissues. The New South Wales Tissue Resource Centre (TRC) in the University of Sydney (Australia) is a human brain bank that can provide tissues to the neuroscience research community studying alcohol-related brain disorders, schizophrenia, depression and bipolar disorders. Carefully standardised operational protocols and integrated information systems means that the TRC can provide high quality, accurately characterised, tissues for research. A recent initiative, the pre-mortem donor program called "Using our Brains", encourages individuals without neuropsychiatric illness to register as control donors, a critical group for all research. Community support for this program is strong with over 2,000 people registering their interest. Discussed herein are the protocols pertaining to this multifaceted facility and the benefits of investment, both scientific and financial, to neuroscience researchers and the community at large.

Predicting the likelihood of future sexual recidivism: pilot study findings from a California sex offender risk project and cross-validation of the Static-99

Pilot findings on 137 California sex offenders followed up over 10 years after release from custody (excluding cases in which legal jurisdiction expired) are presented. The sexual recidivism rate, very likely inflated by sample selection, was 31 percent at five years and 40 percent at 10 years. Cumulatively, markers of sexual deviance (multiple victim types) and criminality (prior parole violations and prison terms) led to improved prediction of sexual recidivism (receiver operating characteristic [ROC] = .71, r = .46) than singly (multiple victim types: ROC = .60, r = .31; prior parole violations and prison terms: ROC = .66, r = .37). Long-term Static-99 statistical predictive accuracy for sexual recidivism was lower in our sample (ROC = .62, r =.24) than the values presented in the developmental norms. Sexual recidivism rates were higher in our study for Static-99 scores of 2 and 3 than in the developmental sample, and lower for scores of 4 and 6. Given failures to replicate developmental norms, the Static-99 method of ranking sexual recidivism risk warrants caution when applied to individual offenders.

Brain donation for research: who donates and why?

Understanding what influences people to donate or not donate body organs is critical for the future of transplant surgery and medical research. Are people involved with a brain donor program for research influenced by the same factors, and are they also donors for organ transplantation? Using web-based technology, people involved in an Australian brain donation program (for research) were asked to complete a questionnaire designed to elicit demographic information, motivational factors and information about involvement in organ transplantation programs. The response rate was 82%. The majority of people involved in the program are young, well-educated Australian females. Seventy-eight percent are involved in other organ and tissue donation programs. People involved in the 'Using our Brains' program are the same group as those who are organ and tissue donors. An improvement in the overall donation rate might be possible if the resources of the research and transplant organisations were combined.

The impact of surgical castration on sexual recidivism risk among sexually violent predatory offenders

The relationship of surgical castration to sexual recidivism in a sexually violent predator/sexually dangerous person (SVP/SDP) population is reviewed. A review of the literature on castrated sex offenders reveals a very low incidence of sexual recidivism. The low sexual recidivism rates reported are critiqued in light of the methodologic limitations of the studies. Better designed testicular/prostate cancer studies have demonstrated that, while sexual desire is reduced by orchiectomy, the capacity to develop an erection in response to sexually stimulating material is not eliminated. The relevance of this literature to SVP/SDP commitment decisions and ethics is discussed. Two vignettes of castrated, high-risk sex offenders illustrate how to address risk reduction. Two tables are presented: the first outlines individual case data from a difficult-to-obtain report, and the second summarizes the most frequently cited castration studies on sexual recidivism. Orchiectomy may have a role in risk assessments; however, other variables should be considered, particularly as the effects can be reversed by replacement testosterone.

Characterization of gabaergic neurons within the human medial mamillary nucleus

The morphology, distribution and relative frequency of GABAergic neurons in the medial mamillary nucleus (MMN) of normal human individuals was studied using a glutamic acid decarboxylase (GAD) antiserum. GAD-immunoreactive (GAD-IR) neurons were found sparsely distributed throughout the MMN and most displayed a simple bipolar morphology. A small population of large diameter GAD-IR neurons was found in the white matter capsule adjacent to the ventral border of the MMN. Results of double-labeling experiments revealed no evidence of calretinin, parvalbumin or calbindin immunoreactivities co-localizing with GAD-IR neurons. GAD-IR neurons of the MMN had an average somal area of 138+/-41 microm2, compared with the average somal area of 384+/-137 microm2 for the population of MMN neurons as a whole. GAD-IR neurons had a tendency to cluster in groups of two (and occasionally three) and showed a distribution gradient across the MMN with higher densities being found near the insertion of the fornix, the origin of the mamillo-thalamic tract and toward the medial MMN border. Quantitative estimates of GAD-IR neuron frequency revealed the GAD-IR phenotype to constitute an average of 1.7% percent of the total neuron population within the human MMN. These findings suggest that inhibitory activity within the human MMN is regulated in part by a small population of intrinsic GABAergic interneurons.

A practical method for the evaluation of symptom exaggeration in minor head trauma among civil litigants

Forensic psychiatrists and psychologists are often called on to provide opinions and render testimony in which minor head trauma accompanied by persistent somatic, cognitive, and/or emotional symptoms is alleged. The frequency of persistent symptoms following such minor head injury is generally low. The forensic clinician therefore must differentiate between subtle brain dysfunction, symptom amplification, psychogenic-based causes for the presence of cognitive and other deficits, or frank malingering. The purpose of this article is twofold: first, to review critical issues related to the assessment of malingering and symptom exaggeration in mild head injury cases; and second, to offer a practical model for the assessment of amplified neuropsychological and psychiatric deficits in civil litigants in cases of minor head trauma.

Expert testimony in sexually violent predator commitments: conceptualizing legal standards of "mental disorder" and "likely to reoffend"

The most recent type of civil commitment for dangerous sex offenders is found under the sexually violent predator laws. Forensic psychiatrists or psychologists must render an opinion as to whether the sex offender has a diagnosed mental disorder and, as such, represents a risk to public safety if released from custody into the community. Thus, expert testimony provided by these professionals has taken a central role in the commitment determinations. There is considerable debate as to what disorders predispose individuals to sexual recidivism and what the term "likely" signifies. In this article, the authors explore the debate in terms of whether Antisocial Personality Disorder is a qualifying diagnosed mental disorder for classification as a sexually violent predator and how a likely threshold of risk of sexual recidivism can be conceptualized.

Stress-induced enhancement of auditory startle: an animal model of posttraumatic stress disorder

An innovative animal model of posttraumatic stress disorder (PTSD) is proposed in which nonhabituation of the acoustic startle response is developed in rats subsequent to tailshock exposure. Subjects (n = 31) received 30 minutes of intermittent tail shock on 2 days followed by exposure to the tailshock apparatus on the third day. Compared to baseline startle reactions, 9 of 31 tailshock-exposed rats developed nonhabituation of startle response reactions during the subsequent 3 weeks of testing. No control rats developed nonhabituation of startle reactions over a similar time period. These data suggest that this system models useful aspects of clinical PTSD emphasizing nonhabituation of startle reactions as a dependent variable. The method consistently identifies a subgroup of rats that develop persistent nonhabituation of startle in response to a tailshock-stress paradigm.

Actuarial risk assessment models: a review of critical issues related to violence and sex-offender recidivism assessments

Risk assessment in the area of identification of violence has been dichotomized by several prominent researchers as the "clinical approach" versus the "actuarial method". The proponents of the actuarial approach argue for actuarially derived decisions to replace existing clinical practice. The actuarial method requires no clinical input, just a translation of the relevant material from the records to calculate the risk score. A risk appraisal approach based upon a sole actuarial method raises several questions: those of public safety, peer-accepted standards of practice, liability issues, and concordance with evidence-based medicine practice. We conclude that the sole actuarial approach fails to satisfy these critical issues.

Size of mamillary bodies in health and disease: useful measurements in neuroradiological diagnosis of Wernicke's encephalopathy

BACKGROUND

As the resolution of noninvasive neuroimaging techniques improves, small structures such as the mamillary bodies can be visualized and measured. The mamillary bodies are pathologically small in a number of neurological disorders, the most common and important is chronic Wernicke's encephalopathy (WE), or the Wernicke-Korsakoff syndrome (WKS), as it is often called. This disorder is caused by vitamin B1 deficiency (thiamin) and is seen most commonly in people who drink excessive amounts of alcohol. The disorder is easily preventable by using oral or parenteral thiamin. The aim of this study was to establish a range for the volume of the mamillary bodies in normal and in various disease states, particularly WE.

METHODS

Brains were taken from 2212 sequential autopsies performed at the New South Wales Institute of Forensic Medicine from 1996 through 1997. After fixation in 10% formalin, the brains were sectioned coronally and a block containing the mamillary bodies was dissected. The maximum vertical and transverse diameters of the mamillary bodies were measured using Mitutoyo vernier callipers and the volume calculated (V = 4/3 (a2b), where a and b are the vertical and transverse radii, respectively).

RESULTS

There were 164 cases with significant pathological changes in the mamillary bodies. These included cases with WE (25), Alzheimer's discase (10), infarction (11), and trauma (55). All but two of the WE cases were chronic or acute on chronic. The mean volume of the mamillary bodies was reduced by 60% in cases with chronic WE and by 25% in cases with Alzheimer's disease. In normal cases, there was a significant age-related reduction in volume, and males had larger mamillary bodies than females. Cases with alcoholic cirrhosis of the liver had normal mamillary body volumes.

CONCLUSIONS

There is a gross shrinkage of the mamillary bodies in cases of chronic WE, but clinicians need to consider other diagnoses, such as Alzheimer's disease, which can also result in shrinkage. These quantitative data will be helpful in the neuroradiological diagnosis of some of these disorders, particularly WE.

Body temperature and wheel running predict survival times in rats exposed to activity-stress

The relationship between restricted feeding, core body temperature (Tb), wheel running, survival, and gastric erosion formation was examined in female rats exposed to activity-stress. Core body temperature and gross motor activity were telemetrically monitored in four groups of rats that had free access to running wheels and in one group that was not allowed to run on the wheels. Twenty-four hours prior to the onset of hypothermia and predicted mortality, different groups were left undisturbed, warmed with a heat lamp, denied access to running wheels, or euthanized. Length of survival in wheel-running rats varied from 2 to 12 days. During the first day of food deprivation, premorbid changes in the variability of Tb during the diurnal period and the mean number of wheel revolutions during the nocturnal period were strongly predictive of length of survival. Warming rats with a heat lamp or preventing rats from ever running on the wheel increased the length of survival and attenuated gastric erosion formation. Only rats that were warmed had a greater likelihood of survival. Gastric pathology was also reduced in rats that were euthanized prior to becoming moribund. Rats that were left undisturbed or locked from the running wheel over the last 24 h of testing became moribund and had extensive gastric mucosal damage. These results indicate that thermoregulatory disturbances induced by restricted feeding and not wheel running alone are critical in determining survival and the degree of gastric mucosal injury in rats exposed to activity-stress. Results further suggest that predisposing factors may put some rats at risk for the development of activity-stress-induced mortality.

Effects of intermittent tail shock or water avoidance on proximal colonic motor contractility in rats

Changes in proximal colonic mechanical activity and defecation during exposure to three different types of experimental stressors were examined in rats chronically implanted with 2 force transducers on the proximal colon. To validate the integrity of the recording system, meal-induced changes in proximal colonic contractility were initially measured in all rats 1-2 days prior to stress induction. Different groups of ad lib fed rats were then exposed to tail shock, re-exposure to the shock chamber or water avoidance for 1 h over the next 1-2 days. Two types of phasic colonic contractions, long (0-3/min) and short (6-8/min) duration, were analyzed separately using a computer. Long duration contractions were significantly elevated 21-71% over fasting basal values from 61-120 min following a meal. No other consistent changes during the prandial or postprandial period were observed. Tail shock significantly suppressed proximal colonic contractility from pre-shock values and increased fecal output and fluid content when compared to ad lib fed rats that were not shocked. Fecal output increased but proximal colonic contractility did not change when previously shocked rats were re-exposed to the tail shock chamber but not shocked. In rats exposed to water avoidance, proximal colonic contractility was minimally suppressed but defecation was significantly greater than home cage control animals. These results indicate that proximal colonic contractile activity is differentially altered by exposure to different environmental stressors and may be a contributing factor in stress-induced bowel dysfunction.

Psychophysiologic parameters of traumatic stress disorder in rats

Nonhabituation of the acoustic startle response is used to identify rat subjects with altered alarm responses subsequent to trauma exposure. Subjects (n = 31) were exposed to 30 minutes of intermittent tail shock on 2 days followed by exposure to the apparatus on the third day. Twenty-nine percent of traumatized rats developed nonhabituation of startle over the subsequent 3 weeks of testing. No control rats developed nonhabituation of startle reactions over a similar time period. These data suggest that this system represents a more accurate representation of clinical PTSD than do other animal models.

Microinjection of thyrotropin-releasing hormone analogue into the central nucleus of the amygdala stimulates gastric contractility in rats

The effect on gastric contractility following bilateral microinjection of thyrotropin-releasing hormone (TRH) analog, RX 77368, into the central nucleus of the amygdala was examined in fasted, urethane-anesthetized rats. Extraluminal force transducers were used to measure gastric corpus contractility. Bilateral microinjection of RX 77368 (0.5 microgram, 1.0 microgram, n = 6 each) stimulated gastric contractility for up to 120 min post-injection, P < 0.05. Gastric contractility was not significantly stimulated by microinjection of 0.1 microgram RX 77368, 0.1% bovine serum albumin (BSA) into the central nucleus or RX 77368 (0.5 microgram, 1.0 microgram) into sites adjacent to the central nucleus. Peak responses (1.0 microgram) occurred 40 min post-injection and represented a 16-26-fold increase over basal values. The frequency of gastric contraction waves was attenuated for 0-90 min in rats receiving central amygdaloid microinjection of RX 77368 (0.1, 0.5 or 1.0 microgram) versus rats microinjected with the vehicle or RX 77368 into sites adjacent to the central nuclei. The stimulatory effect of RX 77368 (1.0 microgram) on gastric contractility was abolished by subdiaphragmatic vagotomy. These results indicate that the TRH analog, RX 77368, acts within the central amygdala to vagally stimulate gastric contractility.

Interleukin-1 beta in the dorsal vagal complex inhibits TRH analogue-induced stimulation of gastric contractility

The effect of murine interleukin-1 beta (mIL-1 beta) microinjected into the dorsal vagal complex (DVC) on thyrotropin-releasing hormone (TRH) analogue (RX-77368)-induced stimulation of gastric contractility was examined in fasted, urethan-anesthetized rats. Gastric corpus contractions were measured with extraluminal force transducers and analyzed by computer. Microinjection of RX-77368 (30 ng) into the right DVC with mIL-1 beta microinjected either into the right (100, 250 pg) or into the left (100, 500 pg) DVC inhibited gastric contractility for 30-120 min postinjection. Peak suppression of gastric contractility (64-78%) occurred at 50-60 min postinjection. Microinjection of mIL-1 beta into the DVC at a lower dose (10 pg) or into sites adjacent to the DVC (100-500 pg) did not suppress the stimulated gastric contractility pattern. Injection of mIL-1 beta (250 pg) or 0.1% bovine serum albumin into the DVC alone did not alter basal gastric contractility. Intracisternal injection of the IL-1 receptor antagonist (250 ng/10 microliters) abolished the inhibitory effect of mIL-1 beta (250 pg) on gastric contractility. These results demonstrate that mIL-1 beta acts in the DVC to inhibit vagally stimulated gastric contractility, and its action is mediated by IL-1 receptors.

Microinjection of thyrotropin-releasing hormone in the paraventricular nucleus of the hypothalamus stimulates gastric contractility

Changes in gastric contractility following microinjection of thyrotropin-releasing hormone (TRH) into the paraventricular nucleus of the hypothalamus (PVN) were examined in fasted, urethane-anesthetized rats. Gastric contractility was measured with extraluminal force transducers and analysed by computer. Unilateral and bilateral PVN microinjections of TRH (0.5 and 1.0 microgram) significantly increased the force index of gastric contractions from 0 to 60 min postinjection, when compared with animals microinjected with 0.1 microgram TRH, 0.1% BSA or TRH (0.5 and 1.0 microgram TRH) in sites adjacent to the PVN. The gastric force index was also significantly elevated from 61 to 120 min postinjection in rats receiving bilateral PVN microinjections of TRH (0.5 and 1.0 microgram). Peak gastric responses occurred within 10-20 min postinjection and represented an approximately eight-fold increase over basal values. In the remaining groups, the force index was not significantly altered from preinjection values. The excitatory action of TRH (1.0 microgram) on gastric contractility was completely abolished by subdiaphragmatic vagotomy. These results suggest that TRH acts within the PVN to stimulate gastric contractility via vagal-dependent pathways.

Raphe pallidus stimulation increases gastric contractility via TRH projections to the dorsal vagal complex in rats

The role of thyrotropin releasing hormone (TRH) in the dorsal vagal complex (DVC) in mediating the enhanced gastric contractility induced by glutamate (100 pmol) microinjected into the raphe pallidus (Rpa) was investigated in urethane-anesthetized rats acutely implanted with miniature strain gauge force transducers on the corpus of the stomach. Glutamate-induced stimulation of gastric contractility was dose-dependently inhibited by bilateral microinjection into the DVC of TRH antibody (0.17, 0.85 or 1.7 micrograms/100 nl/site) but not by vehicle. TRH antibody microinjected into the dorsal medullary reticular field had no effect. These data indicate that activation of Rpa neurons by glutamate increases gastric motor function through TRH release in the DVC.

Myth of substituted judgment. Surrogate decision making regarding life support is unreliable

OBJECTIVE

To identify factors predicting the accuracy of surrogate decision making in life support decisions.

DESIGN

Questionnaire.

SETTING

Urban Veterans Affairs hospital.

PATIENTS AND DESIGN

Fifty hospitalized patients and their chosen surrogates were given questionnaires describing life support modalities and four common medical scenarios in which life support would be contemplated. An additional 50 patients also completed the questionnaire. Patients gave their choices of life support in the different scenarios. Surrogates guessed the patients' answers (substituted judgment). Details of the patient-surrogate relationship were asked. Patients completed a depression inventory.

MAIN RESULTS

Surrogates correctly guessed patients' wishes about life support overall on 59.3% of the questions, not better than random chance (kappa = .09). The only predictor of accurate surrogate decision making was specific discussion between patient and surrogate about life support. SECONDARY RESULTS: Patients had an overall low desire for life support (35%), and a majority favored euthanasia under some circumstances (62%). There was no relationship between depression score and desire for life support.

CONCLUSIONS

Substituted judgment by surrogates is not more accurate than random chance. Discussion between patient and surrogate about life support correlated with more accurate substituted judgment.

Lateral hypothalamic lesions cause gastric injury by stimulating gastric contractility

Changes in gastric contractility following lateral hypothalamic (LH) lesions with and without bilateral cervical vagotomy were measured in urethan-anesthetized rats. LH lesions were induced with direct current passed through stereotaxically placed electrodes. Gastric contractility was recorded continuously for 4 h with acutely implanted strain gauge force transducers and analyzed by computer. LH lesions consistently stimulated gastric contractility and caused more gastric mucosal injury than control conditions. Vagotomy blocked both gastric mucosal injury and high-amplitude gastric contractions. In rats with LH lesions and exogenously infused intragastric hydrochloric acid, atropine methyl nitrate inhibited high-amplitude gastric contractions and gastric erosions. These findings indicate that LH lesions stimulate vagally mediated high-amplitude gastric contractions, which, in the presence of hydrochloric acid, cause gastric mucosal erosions.

Effects of preadaptation to restricted feeding and cimetidine treatment on gastric mucosal injury and wheel running during exposure to activity-stress

The relationship between gastric injury and wheel running was examined during an activity-stress (A-S) experiment. In Experiment 1, rats were preadapted to a 1-h restricted feeding schedule for either 0, 15, 25 or 35 days prior to entering activity wheels. All rats preadapted to the 1-h feeding schedule had significantly less gastric damage than rats without any preadaptation experience. Survival of A-S was related to the length of preadaptation experience. Regardless of preadaptation experience, rats increased daily running with the greatest increase occurring during the 6-h period preceding the feeding hour. In Experiment 2, rats were injected twice daily with cimetidine (100 mg, ip) or vehicle during the 6-h preceding the feeding session. Rats treated with cimetidine had less mucosal injury but had no increased survival when compared to rats injected with the vehicle. Cimetidine treated rats had essentially the same running pattern as controls. These results demonstrated that the process of mucosal injury did not stimulate excessive wheel running. The data also suggest that mucosal injury is not related to survival in A-S rats.

Thyrotropin-releasing hormone analog injected into the raphe pallidus and obscurus increases gastric contractility in rats

The present study was performed to investigate the influence of the chemical stimulation of medullary raphe nuclei by the stable TRH (thyrotropin-releasing hormone) analog, RX 77368, on gastric contractility. Urethane-anesthetized rats were acutely implanted with miniature strain gauge force transducers on the corpus of the stomach for continuous recording of gastric contractility. Traces were analyzed by computer. Microinjections of vehicle or RX 77368 into the raphe pallidus or raphe obscurus were performed using pressure injection of 50 nl through glass micropipettes 30 min following basal recording of gastric contractility. RX 77368 (0.7-77 pmol) dose dependently stimulated gastric contractility when microinjected into the raphe pallidus and raphe obscurus. The stimulation of gastric contractions induced by microinjection of RX 77368 (77 pmol) into these raphe nuclei was completely blocked by vagotomy and prevented (raphe obscurus) or reduced (raphe pallidus) by atropine. RX 77368 (7.7-77 pmol) microinjected into the inferior olive, pyramidal tract, medial lemiscus was ineffective. These results demonstrate that chemical stimulation of the raphe pallidus and obscurus by RX 77368 stimulates gastric contractility through vagal and muscarinic pathways. These data suggest a role for medullary raphe nuclei in the central vagal regulation of gastric contractility.

CRF microinjected into the dorsal vagal complex inhibits TRH analog- and kainic acid-stimulated gastric contractility in rats

The effect of CRF microinjected into the dorsal vagal complex (DVC) on centrally-stimulated gastric contractility was investigated in fasted, urethane-anesthetized rats. Miniature strain gauge force transducers were acutely implanted on the corpus of the stomach and contractility was analyzed by computer. Microinjection of the stable thyrotropin-releasing hormone (TRH) analog, RX 77368, (26 pmol) into the DVC induced a 12.2-fold stimulation of gastric contractility within 30 min. Corticotropin-releasing factor (CRF) (63-210 pmol) microinjected into the DVC concomitantly with RX 77368 (26 pmol) induced a dose-related inhibition of stimulated gastric contractility. Neither CRF alone (210 pmol) nor vehicle modified basal gastric contractility. Microinjection of kainic acid (141 pmol) into the raphe pallidus nucleus induced a 3.6-fold stimulation of gastric contractility after 45 min. This stimulation was suppressed by bilateral microinjection of CRF (105 pmol/site) into the DVC. These results demonstrate that CRF acts in the DVC to inhibit centrally-stimulated gastric contractility and suggest that TRH and CRF may interact in the DVC to regulate gastric motor function.

Elevated intracranial pressure stimulates gastric contractility in the rat

The gastric contractile response to elevated intracranial pressure (ICP) was studied in conscious rats. Elevation of intracranial pressure to 20 mm Hg was associated with a marked increase in the amplitude of gastric contractions (70-90% over baseline) without any change in contractile frequency (5.2 +/- .5 contractions per min). The increase in contractility continued for 45 min following release of the pressure. Vagotomy completely blocked the increase in gastric contractility seen with elevation in ICP. We conclude that acute elevation of intracranial pressure in rats results in increased force of gastric contractions. The forceful contractions persist despite release of the pressure and the increased contractile force is vagally mediated.

Bombesin microinjected into the dorsal vagal complex inhibits TRH-stimulated gastric contractility in rats

The effects of centrally injected bombesin on central and peripheral stimulated gastric contractility were investigated in fasted urethane-anesthetized rats. Miniature strain gauge force transducers were acutely implanted on the corpus of the stomach and gastric contractility was analyzed by computer. Intracisternal injection of the stable thyrotropin-releasing hormone (TRH)-analog RX 77368 (77 pmol) induced a stimulation of gastric contractility for 40 min. Intracisternal injection of bombesin (62-620 pmol) followed 30 min later by that of RX 77368 resulted in a dose-related inhibition of the TRH-analog-induced gastric contractility. Intracisternal injection of bombesin (620 pmol) did not modify gastric contractility stimulated by intravenous carbachol. Stimulation of gastric contractility induced by TRH-analog microinjected into the dorsal vagal complex (DVC) was dose-related suppressed by concomitant injections of bombesin (6.2-620 pmol). Neither bombesin alone (6.2 pmol) nor vehicle modified basal gastric contractility. These results demonstrate that bombesin acts within the brain to inhibit vagally stimulated gastric contractility and that the DVC is a sensitive site for bombesin inhibitory action. These findings suggest a possible interaction between TRH and bombesin in the central vagal regulation of gastric contractility.

Endogenous serotonin produces an inhibitory tone on vagally stimulated gastric function

The effect of depletion of serotonin stores on vagally stimulated gastric acid secretion and motility was studied in rats. Pretreatment of rats with parachlorophenylalanine (p-CPA) produced a 57% reduction in the intraluminal gastric release of serotonin and a 43-100% potentiation of the gastric acid secretory response elicited by intracisternal injection of the stable TRH analogue RX 77368 in conscious pylorusligated rats or in urethane-anesthetized rats with an acute gastric fistula. p-CPA also enhanced the vagally stimulated gastric acid output produced by intravenous injection of baclofen. In contrast, p-CPA pretreament had no effect on gastric acid secretion stimulated by bethanechol, histamine, or pentagastrin. Selective depletion of central serotonin stores by the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) given alone or combined with parachloroamphetamine pretreatment did not alter RX 77368-stimulated gastric acid secretion. In addition, gastric contractility stimulated by intracisternal injection of RX 77368 was significantly enhanced by p-CPA but not by 5,7-DHT pretreatment; whereas the contractile response to carbachol was not altered by p-CPA pretreatment. These results suggest that depletion of peripheral but not central serotonergic stores potentiates gastric acid secretion and contractility stimulated by vagally, but not peripherally, acting gastric stimulants. Thus, peripheral serotonin may exert an inhibitory tone on vagally stimulated gastric acid secretion and motility in the rat.

Central nervous system action of peptides to influence gastrointestinal motor function

The central action of peptides to influence GI motility in experimental animals is summarized in Table 1. TRH stimulates gastric, intestinal, and colonic contractility in rats and in several experimental species. A number of peptides including calcitonin, CGRP, neurotensin, NPY, and mu opioid peptides act centrally to induce a fasted MMC pattern of intestinal motility in fed animals while GRF and substance P shorten its duration. The dorsal vagal complex is site of action for TRH-, bombesin-, and somatostatin-induced stimulation of gastric contractility, and for CCK-, oxytocin- and substance P-induced decrease in gastric contractions or intraluminal pressure. The mechanisms through which TRH, bombesin, calcitonin, neurotensin, CCK, and oxytocin alter GI motility are vagally mediated. An involvement of central peptidergic neurons in the regulation of gut motility has recently been demonstrated in Aplysia, indicating that such regulatory mechanisms are important in the phylogenesis. Alterations of the pattern of GI motor activity are associated with functional changes in transit. TRH is so far the only centrally acting peptide stimulating simultaneously gastric, intestinal, and colonic transit in various animals species. Opioid peptides acting on mu receptor subtypes in the brain exert the opposite effect and inhibit concomitantly gastric, intestinal, and colonic transit. Bombesin and CRF were found to act centrally to inhibit gastric and intestinal transit and to stimulate colonic transit in the rat. The antitransit effect of calcitonin and CGRP is limited to the stomach and small intestine. The delay in GI transit is associated with reduced GI contractility for most of the peptides except central bombesin that increases GI motility. Nothing is known about brain sites through which these peptides act to alter gastric emptying and colonic transit. Regarding brain sites influencing intestinal transit, TRH-induced stimulation of intestinal transit in the rat is localized in the lateral and medial hypothalamus and medial septum. The periaqueductal gray matter is a responsive site for mu receptor agonist- and neurotensin-induced inhibition of intestinal transit. The neural pathways from the brain to the gut whereby these peptides express their stimulatory or inhibitory effects on GI transit is vagal dependent with the exception of calcitonin. It is not known whether the vagally mediated inhibition of GI transit by these peptides results from a decrease activity of vagal preganglionic fibers synapsing with excitatory myenteric neurons or an activation of vagal preganglionic neurons synapsing with inhibitory myenteric neurons. The lack of specific antagonists for these peptides has hampered the assessment of their physiological role.(ABSTRACT TRUNCATED AT 400 WORDS)

Serotonin depletion potentiates gastric secretory and motor responses to vagal but not peripheral gastric stimulants

Vagal stimulation is known to release gastrointestinal serotonin. The effect of depletion of serotonin stores on vagally stimulated gastric acid secretion and motility was studied in rats. Pretreatment of rats with parachlorophenylalanine (p-CPA) did not alter basal gastric acid and serotonin secretion but produced a 57% reduction in the intraluminal gastric release of serotonin and a 43 to 100% potentiation of the gastric acid secretory response elicited by intracisternal injection of the stable thyrotropin-releasing hormone analog, RX 77368, in conscious pylorus-ligated rats or urethane-anesthetized rats with an acute gastric fistula. Dose-response studies revealed that the gastric acid secretion induced by submaximal but not high doses of RX 77368 was elevated significantly by p-CPA pretreatment. p-CPA also enhanced the gastric acid output produced by submaximal, but not high doses of the vagal stimulant baclofen, [beta-(p-chlorophenyl)-gamma-aminobutyric acid]. In contrast, p-CPA pretreatment had no effect on gastric acid secretion stimulated by bethanechol, histamine or pentagastrin. Selective depletion of central serotonin stores by pretreatment with the neurotoxin 5,7-dihydroxytryptamine given alone, or combined with parachloroamphetamine did not alter RX 77368-stimulated gastric acid secretion. In addition, gastric contractility stimulated by intracisternal injection of RX 77368 was significantly enhanced by p-CPA but not by 5,7-dihydroxytryptamine pretreatment, whereas the contractile response to carbachol was not altered by p-CPA pretreatment. These results suggest that depletion of peripheral but not central serotonergic stores potentiate gastric acid secretion and contractility induced by vagally, but not peripherally acting gastric stimulants. Thus, peripheral serotonin may exert an inhibitory tone on vagally stimulated gastric acid secretion and motility in the rat.

Medullary sites for TRH analogue stimulation of gastric contractility in the rat

Medullary sites at which the stable thyrotropin-releasing hormone (TRH) analogue, RX 77368 (p-Glu-His-[3,3'-dimethyl]-Pro-NH2), stimulates gastric contractility were investigated in rats under urethan anesthesia. The peptide analogue was microinjected in 50-100 nl of volume unilaterally into various brain stem nuclei using glass micropipettes (50 microns). Gastric contractility was recorded continuously with acutely implanted strain-gauge force transducers and traces analyzed by computer. RX 77368 (2.6-77 pmol) microinjected into the dorsal vagal complex (DVC) dose dependently stimulated gastric contractility. Peptide action (77 pmol) had a rapid onset with a peak response at 15 min, continued for 45 min after the microinjection, and was blocked by vagotomy. TRH microinjected into the DVC had a shorter duration of action. RX 77368 (0.7-77 pmol) microinjected into the nucleus ambiguus also dose dependently stimulated gastric contractions. In contrast, microinjection of RX 77368 (77 pmol) into the hypoglossal nucleus had no effect. These findings demonstrate that the DVC and nucleus ambiguus are sites of action for TRH-induced stimulation of gastric contractility in the rat. The effect is dose dependent, long lasting, site specific, and vagally mediated. These results are consistent with a possible physiological role for medullary TRH in the vagal regulation of gastric contractility.

Predictable and unpredictable shock stimulates gastric contractility and causes mucosal injury in rats

The effects of tailshock on gastric contractility and lesions were investigated in rats exposed to 100 1-mA tailshocks while confined inside plastic tubes. A light preceded each shock in one group and was randomly presented with respect to shock in the other. Following the session, animals were given 3 hr of rest before being sacrificed. Contractility of the corpus of the stomach was measured by means of chronically implanted extraluminal force transducers. Contractility was measured in 10-min blocks and analyzed by computer. Lesions were quantified by inspection; quantitative histology was performed on corpus and antrum sections. Signaled (n = 13) and unsignaled (n = 17) shock stimulated high-amplitude gastric contractions in fasted rats, which continued for 2 hr after the shock session. Cumulative contractile activity (1.5-hr shock plus 2-hr rest) in shocked animals was twice that in restrained and unrestrained control animals (n = 19, p less than .05), and contractile activity had a 30%-40% greater average amplitude than after a meal. Compared with unrestrained controls, shocked rats had visibly more mucosal injury (2.2 +/- 0.5 mm2 vs. 0.1 +/- 0 mm2). Larger cumulative contractile activity was associated with a larger area of erosions (r = .36, p less than .05). Frequency and duration of contractions did not distinguish between shocked and unshocked groups. We conclude that in rats, signaled and unsignaled tailshock stimulates persistent, high-amplitude gastric contractions and is associated with injury of the mucosa of the stomach.

Predictable and unpredictable shock stimulates gastric contractility and causes mucosal injury in rats

The effects of tailshock on gastric contractility and lesions were investigated in rats exposed to 100 1-mA tailshocks while confined inside plastic tubes. A light preceded each shock in one group and was randomly presented with respect to shock in the other. Following the session, animals were given 3 hr of rest before being sacrificed. Contractility of the corpus of the stomach was measured by means of chronically implanted extraluminal force transducers. Contractility was measured in 10-min blocks and analyzed by computer. Lesions were quantified by inspection; quantitative histology was performed on corpus and antrum sections. Signaled (n = 13) and unsignaled (n = 17) shock stimulated high-amplitude gastric contractions in fasted rats, which continued for 2 hr after the shock session. Cumulative contractile activity (1.5-hr shock plus 2-hr rest) in shocked animals was twice that in restrained and unrestrained control animals (n = 19, p less than .05), and contractile activity had a 30%-40% greater average amplitude than after a meal. Compared with unrestrained controls, shocked rats had visibly more mucosal injury (2.2 +/- 0.5 mm2 vs. 0.1 +/- 0 mm2). Larger cumulative contractile activity was associated with a larger area of erosions (r = .36, p less than .05). Frequency and duration of contractions did not distinguish between shocked and unshocked groups. We conclude that in rats, signaled and unsignaled tailshock stimulates persistent, high-amplitude gastric contractions and is associated with injury of the mucosa of the stomach.

Intracerebroventricular pressure inhibits gastric antral and duodenal contractility but not acid secretion in conscious rabbits

Acute nausea characteristically accompanies head injury or increased intracranial pressure, or both. The etiology of this symptom is unclear. We studied the effect of increased intracranial pressure on gastric antral and duodenal contractility and gastric acid secretion in conscious rabbits. Intracerebroventricular pressure was maintained at 3, 8, or 13 cmH2O using normal saline perfused into the lateral cerebral ventricle and gastric antral and duodenal contractility was monitored using chronically implanted strain gauge force transducers. Gastric acid secretion was measured in a separate group of rabbits with chronically implanted gastric cannulas. Increased intracerebroventricular pressure (13 cmH2O) resulted in an immediate suppression of the amplitude of gastric and duodenal contractions by greater than 80% and greater than 60%, respectively. After normalization of intracerebroventricular pressure, the contractile pattern returned to basal levels. Intravenous bolus injection of bethanechol reversed the suppression of gastric antral contractility induced by increased intracranial pressure. Increased pressure for 2 h did not modify gastric acid output as compared with normal pressure controls, whereas atropine significantly inhibited and histamine stimulated gastric acid secretion in the same animals maintained at normal pressure. These results demonstrate that acutely increased intracranial pressure rapidly and reversibly inhibits gastric and duodenal motor function in conscious rabbits.

Corticotropin-releasing factor acts centrally to suppress stimulated gastric contractility in the rat

The effects of intracisternal (i.c.) and intravenous (i.v.) administration of corticotropin-releasing factor (CRF) on gastric contractility stimulated by i.c. injection of the TRH analog RX77368 [p-Glu-His-(3,3'-dimethyl)-Pro-NH2], 2-deoxy-D-glucose (2DG) and i.v. infusion of carbachol were evaluated in rats under urethane anesthesia. Gastric contractility was monitored using acutely implanted extraluminal force transducers sutured to the corpus of the stomach. I.c. injection of CRF (6.3-210 pmol) resulted in a dose dependent suppression of gastric contractility stimulated by RX77368 (260 pmol) and 2DG (6 mg). Gastric inhibitory response to i.c. CRF was rapid in onset and lasted at least 45 min. Carbachol (200 mg/kg/h)-induced stimulation of gastric contractility was not modified by i.c. injection of CRF. The stimulation of contractility caused by both i.v. carbachol and i.c. 2DG were completely inhibited by atropine (1 mg/kg, i.v.). CRF (210 pmol) given i.v. suppressed RX77368-stimulated gastric contractions, but was less than 1/10 as potent as administered i.c. I.v. CRF (210 pmol) did not alter 2DG- or carbachol-induced gastric contractions. These results demonstrate that the i.c. administration of CRF acts within the brain to inhibit gastric contractility elicited by vagus-dependent mechanisms.

Central nervous system action of TRH to stimulate gastric function and ulceration

Intracisternal or intracerebroventricular injection of TRH (0.1-10 micrograms) in rats stimulated the secretion of gastric acid and pepsin secretion, increased gastric mucosal blood flow and gastric contractility and emptying, induced gastric hemorrhagic lesions and aggravated experimental ulcers elicited by aspirin, serotonin or indomethacin. TRH action was dose-dependent, rapid in onset and central nervous system-mediated by activation of the parasympathetic outflow to the stomach and cholinergic receptors. The stable TRH analog, RX 77368, was more potent and longer lasting than TRH. TRH and its stable analog appear as new chemical probes to produce centrally-mediated vagal-dependent stimulation of gastric function and experimental ulcers. The physiologic role of endogenous TRH in the central regulation of gastric function and ulceration remains to be established.

Cimetidine and ranitidine protect against cold restraint-induced ulceration in rat by suppressing gastric acid secretion

The effect of the H2-receptor antagonists cimetidine and ranitidine on pentagastrin-stimulated gastric acid secretion in anesthetized rats, and gastric mucosal lesion formation and gastric motility in unanesthetized cold-restrained rats was studied. Both cimetidine and ranitidine suppressed pentagastrin-stimulated gastric secretion in a dose-dependent fashion. Cold restraint-induced lesion formation was not prevented with doses of both agents that inhibited acid secretion by 75%. Doses which suppressed pentagastrin-stimulated acid secretion more than 90% significantly prevented the development of gastric mucosal lesions produced by cold restraint. Doses of both H2 blockers which demonstrated significant suppression of lesion formation had no effect on cold restraint-stimulated gastric contractility. We conclude that cimetidine and ranitidine suppress cold restraint-induced lesion formation by suppressing acid secretion and not by suppressing gastric contractility.

Thyrotropin-releasing hormone (TRH) acts centrally to stimulate gastric contractility in rats

Changes in gastric contractility induced by intracisternal (ic) injection of thyrotropin-releasing hormone (TRH) or a stable TRH analog, RX77368 [p-Glu-His-(3,3'-dimethyl)-Pro NH2] were investigated in 24 h fasted-conscious rats. Gastric contractility was monitored using chronically implanted extraluminal force transducers sutured to the corpus. Response elicited by a standard meal was used as a physiologic standard. Intracisternal injection of TRH (1 microgram) or RX77368 (100 ng), unlike saline, stimulated high amplitude gastric contractions. The stimulation of gastric contractions induced by ic RX77368 was dose dependent (3-100 ng), rapid in onset, long lasting and not mimicked by the intravenous route of administration. Atropine (0.1 mg/kg) partially antagonized and vagotomy totally blocked the RX77368 (100 ng, ic)-induced stimulation of gastric contractility. These results demonstrated that TRH or RX77368 acts within the brain to elicit potent contractions of the stomach; TRH action appears vagally mediated probably through cholinergic mechanism.

Corticotropin-releasing factor acts on the brain to reduce gastric contractility

Various stressors (cold restraint, electric shock, etc.) applied to rats increase gastric contractility and are associated with gastric erosions. Intracisternal (i.c.) thyrotropin-releasing hormone (TRH) increases contractility, gastric acid secretion and the incidence of erosion formation. Corticotropin-releasing hormone (CRF) is released by stress, and acting centrally produces autonomic and endocrine changes. We have studied the role of i.c. CRF on gastric contractility in anesthetized rats (n = 6). Contractility was measured by extraluminal force transducers sutured to the gastric corpus. Frequency, amplitude of contractions and a motility index were analyzed by computer. Baseline measures, after recovery from surgery were obtained in 24-hour fasted rats. Contractility was stimulated by intravenous carbachol (100 mg/kg/h) or i.c. injection of the TRH analog, RX 77368. Contractility thus induced was inhibited by intravenous atropine (1 mg/kg). CRF (30-1,000 ng i.c.) produced a dose-dependent suppression of RX 77368 (p less than 0.05) but had no effect on that induced by intravenous carbachol; saline i.c. had none either. Intravenous CRF was 1/10th as potent in suppressing contractions produced by i.c. RX 77368. Diminution of gastric contractions after i.c. CRF (1 mg) occurred within 5 min of administration, and lasted for at least 60 min. These data show that i.c. CRF injection acts centrally to inhibit gastric contractions stimulated centrally (i.e. by i.c. RX 77368) but not peripherally (i.e. by carbachol), and by inference reduces the risk of erosion formation induced by some stressors.

Gastric motility is stimulated but overall blood flow is unaffected during cold restraint in the rat

The relationship between cold restraint-induced lesion formation, gastric motility, and gastric mucosal blood flow was studied in rats. Both anesthetized and unanesthetized animals placed in cold restraint developed gastric mucosal lesions. Gastric (corpus) motility was measured using extraluminal force transducers. Animals placed in cold restraint developed persistent, high amplitude, prolonged duration contractions. Those rats in which such contractions lasted greater than 1 h developed gastric mucosal lesions, whereas those animals in which such contractions lasted less than or equal to 1 h had no lesions. Overall gastric mucosal blood flow was measured using the hydrogen gas clearance technique. There was no significant change in overall gastric mucosal blood flow measured after 1, 2, and 3 h of cold restraint. We conclude that (a) the physical effect of cold water immersion is by itself sufficient to cause cold "restraint" lesions and (b) such lesions are associated with high amplitude, prolonged duration contractions lasting greater than 1 h.