Cholecystokinin inhibits tail pinch-induced eating in rats.

Peripheral administration of the COOH-terminal octapeptide of cholecystokinin in doses from 1 to 100 micrograms per kilogram of body weight (0.25 to 25.0 micrograms per rat) significantly antagonized tail pinch-induced eating in rats, an animal model for stress-induced human hyperphagia. Centrally administered cholecystokinin was effective only in high doses (3 micrograms into the cerebral ventricle). The finding that the minimal effective dose of cholecystokinin in suppressing stress-induced appetitive behavior is smaller after peripheral than central administration suggests that the peptide is acting on peripheral, as opposed to central nervous system, substrates.

Elevated concentrations of CSF corticotropin-releasing factor-like immunoreactivity in depressed patients.

The possibility that hypersecretion of corticotropin-releasing factor (CRF) contributes to the hyperactivity of the hypothalamo-pituitary-adrenal axis observed in patients with major depression was investigated by measuring the concentration of this peptide in cerebrospinal fluid of normal healthy volunteers and in drug-free patients with DSM-III diagnoses of major depression, schizophrenia, or dementia. When compared to the controls and the other diagnostic groups, the patients with major depression showed significantly increased cerebrospinal fluid concentrations of CRF-like immunoreactivity; in 11 of the 23 depressed patients this immunoreactivity was greater than the highest value in the normal controls. These findings are concordant with the hypothesis that CRF hypersecretion is, at least in part, responsible for the hyperactivity of the hypothalamo-pituitary-adrenal axis characteristic of major depression.

Rapid eye movement sleep deprivation decreases long-term potentiation stability and affects some glutamatergic signaling proteins during hippocampal development.

Development of the mammalian CNS requires formation and stabilization of neuronal circuits and synaptic connections. Sensory stimulation provided by the environment orchestrates neuronal circuit formation in the waking state. Endogenous sources of activation are also implicated in these processes. Accordingly we hypothesized that sleep, especially rapid eye movement sleep (REMS), the stage characterized by high neuronal activity that is more prominent in development than adulthood, provides endogenous stimulation, which, like sensory input, helps to stabilize and refine neuronal circuits during CNS development. Young (Y: postnatal day (PN) 16) and adolescent (A: PN44) rats were rapid eye movement sleep-deprived (REMSD) by gentle cage-shaking for only 4 h on 3 consecutive days (total 12 h). The effect of REMS deprivation in Y and A rats was tested 3-7 days after the last deprivation session (Y, PN21-25; A, PN49-53) and was compared with younger (immature, I, PN9-12) untreated, age-matched, treated and normal control groups. REMS deprivation negatively affected the stability of long-term potentiation (LTP) in Y but not A animals. LTP instability in Y-REMSD animals was similar to the instability in even the more immature, untreated animals. Utilizing immunoblots, we identified changes in molecular components of glutamatergic synapses known to participate in mechanisms of synaptic refinement and plasticity. Overall, N-methyl-d-aspartate receptor subunit 2B (NR2B), N-methyl-d-aspartate receptor subunit 2A, AMPA receptor subunit 1 (GluR1), postsynaptic density protein 95 (PSD-95), and calcium/calmodulin kinase II tended to be lower in Y REMSD animals (NR2B, GluR1 and PSD-95 were significantly lower) compared with controls, an effect not present in the A animals. Taken together, these data indicate that early-life REMS deprivation reduces stability of hippocampal neuronal circuits, possibly by hindering expression of mature glutamatergic synaptic components. The findings support a role for REMS in the maturation of hippocampal neuronal circuits.

Overexpression of the high affinity choline transporter in cortical regions affected by Alzheimer's disease. Evidence from rapid autopsy studies.

Cholinergic deficits in Alzheimer's disease are typically assessed by choline acetyltransferase, the enzyme that synthesizes acetylcholine. However, the determining step in acetylcholine formation is choline uptake via a high affinity transporter in nerve terminal membranes. Evaluating uptake is difficult because regulatory changes in transporter function decay rapidly postmortem. To overcome this problem, brain regions from patients with or without Alzheimer's disease were frozen within 4 h of death and examined for both choline acetyltransferase activity and for binding of [3H]-hemicholinium-3 to the choline transporter. Consistent with the loss of cholinergic projections, cerebral cortical areas exhibited marked decreases in enzyme activity whereas the putamen, a region not involved in Alzheimer's disease, was unaffected. However, [3H]hemicholinium-3 binding was significantly enhanced in the cortical regions. In the frontal cortex, the increase in [3H]hemicholinium-3 binding far exceeded the loss of choline acetyltransferase, indicating transporter overexpression beyond that necessary to offset loss of synaptic terminals. These results suggest that, in Alzheimer's disease, the loss of cholinergic function is not dictated simply by destruction of nerve terminals, but rather involves additional alterations in choline utilization; interventions aimed at increasing the activity of cholinergic neurons may thus accelerate neurodegeneration.

Neuroprotective effects of agmatine against cell damage caused by glucocorticoids in cultured rat hippocampal neurons.

In the present study the neuroprotective effects of agmatine against neuronal damage caused by glucocorticoids were examined in cultured rat hippocampal neurons. Spectrophotometric measurements of lactate dehydrogenase activities, beta-tubulin III immunocytochemical staining, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick-end-labeling assay (TUNEL) labeling and caspase-3 assays were carried out to detect cell damage or possible involved mechanisms. Our results show that dexamethasone and corticosterone produced a concentration-dependent increase of lactate dehydrogenase release in 12-day hippocampal cultures. Addition of 100 microM agmatine into media prevented the glucocorticoid-induced increase of lactate dehydrogenase release, an effect also shared with the specific N-methyl-D-aspartate receptor antagonist MK801 and glucocorticoid receptor antagonists mifepristone and spironolactone. Arcaine, an analog of agmatine with similar structure as agmatine, also blocked glucocorticoid-induced increase of lactate dehydrogenase release. Spermine and putrescine, the endogenous polyamine and metabolic products of agmatine without the guanidino moiety of agmatine, have no appreciable effect on glucocorticoid-induced injuries, indicating a structural relevance for this neuroprotection. Immunocytochemical staining with beta-tubulin III confirmed the substantial neuronal injuries caused by glucocorticoids and the neuroprotective effects of agmatine against these neuronal injuries. TUNEL labeling demonstrated that agmatine significantly reduced TUNEL-positive cell numbers induced by exposure of cultured neurons to dexamethasone. Moreover, exposure of hippocampal neurons to dexamethasone significantly increased caspase-3 activity, which was inhibited by co-treatment with agmatine. Taken together, these results demonstrate that agmatine can protect cultured hippocampal neurons from glucocorticoid-induced neurotoxicity, through a possible blockade of the N-methyl-D-aspartate receptor channels or a potential anti-apoptotic property.

Reduced corticotropin releasing factor binding sites in the frontal cortex of suicide victims.

Previous studies have provided evidence that corticotropin releasing factor (CRF) is hypersecreted in patients with major depression. This CRF hypersecretion is believed to contribute at least in part to hyperactivity of the hypothalamic-pituitary-adrenal axis in depressed patients. If CRF is chronically hypersecreted in depressed patients, then, due to down-regulation, a reduced number of CRF receptor binding sites should be present in patients with profound depressive disorder. To test this hypothesis, we measured the number and affinity of CRF binding sites in the frontal cortex of 26 suicide victims and 29 controls who died of a variety of causes. There was a marked (23%) reduction in the number of CRF binding sites in the frontal cortex of the suicide victims compared with the controls. These data are consistent with the hypothesis that CRF is hypersecreted in depression.

Carbamazepine increases cerebrospinal fluid thyrotropin-releasing hormone levels in affectively ill patients.

BACKGROUND: Thyrotropin-releasing hormone is an endogenous tripeptide with endocrine-independent neurophysiologic properties that may be relevant to affective or seizure disorders. We studied the effect of carbamazepine, which has both mood-stabilizing and anticonvulsant properties, on cerebrospinal fluid thyrotropin-releasing hormone levels in affectively ill patients. METHOD: Paired cerebrospinal fluid samples were collected from nine inpatients with mood disorders, both while medication free and while taking carbamazepine for an average of longer than 1 month at 950 mg/d, achieving blood levels of 8.8 mg/L. RESULTS: Carbamazepine treatment was consistently and significantly associated with increased cerebrospinal fluid thyrotropin-releasing hormone levels (P < .0001). CONCLUSION: As carbamazepine-induced increases in thyrotropin-releasing hormone levels could be relevant to either its psychotropic or anticonvulsant properties, further clinical and preclinical investigation of this finding appears indicated.

Alterations in cerebrospinal fluid concentrations of somatostatinlike immunoreactivity in neuropsychiatric disorders.

The concentration of somatostatinlike immunoreactivity in cerebrospinal fluid (CSF) from normal, healthy volunteers (n = 10) and patients with DSM-III diagnoses of major depression (n = 17), schizophrenia (n = 11), or dementia (n = 29) was measured by a sensitive and specific radioimmunoassay. Statistically significant decreases in CSF concentrations of somatostatinlike immunoreactivity were seen in all three patient populations when compared with controls. These findings confirm previous reports of decreased concentrations of somatostatinlike immunoreactivity in the CSF of patients with depression and dementia and extend this observation to patients with schizophrenia as well. These findings are concordant with the view that reductions in somatostatinlike immunoreactivity concentrations are associated with diseases in which cognitive function is disturbed.

Alterations in Alzheimer's disease-associated protein in Alzheimer's disease frontal and temporal cortex.

Alzheimer's disease (AD)-associated protein is present in brain and cerebrospinal fluid of patients with AD but not in adult, nondemented, normal controls. This protein may represent an abnormal epitope of the "tau" microtubule-associated protein and has been detected before the appearance of senile plaques and neurofibrillary tangles. The amount of AD-associated protein in the frontal and temporal cortices in 93 cases of neuropathologically confirmed AD was compared with the amount that was present in 20 cases without AD. The amount of AD-associated protein was significantly increased in the cases of AD for both brain regions compared with that in the cases without AD. The presence of high levels of this protein is a useful adjunct, postmortem marker of the presence of AD and may eventually lead to tests that allow early detection of individuals at risk for this disease.

Personality profiles and state aggressiveness in Finnish alcoholic, violent offenders, fire setters, and healthy volunteers.

BACKGROUND: Based on clinical observations in a series of studies on Finnish alcoholic, violent offenders, we asserted that the impulsive offenders represented an extreme group of type 2 alcoholics. We also observed that these subjects were vulnerable to hypoglycemia after the administration of oral glucose load. Furthermore, we believe that while being hypoglycemic, the impulsive offenders are particularly irritable and aggressive. In the present study, we addressed these issues by studying psychological trait and state variables in a new group of violent offenders and fire setters, and age- and sex-matched healthy volunteers. METHODS: Fifty-eight alcoholic, violent offenders and impulsive fire setters and 21 healthy volunteers were administered the Karolinska scales of personality and the Rosenzweig picture frustration test after an oral aspartame and glucose challenge. RESULTS: The psychological test results and the criminal histories of the offenders, together with biochemical measurements, suggest that a low 5-hydroxyindoleacetic acid concentration in cerebrospinal fluid in the alcoholic offenders is associated with irritability and impaired impulse control, and a high free testosterone concentration in cerebrospinal fluid is associated with increased aggressiveness, monotony avoidance, sensation seeking, suspiciousness, and reduced socialization. CONCLUSION: Finnish alcoholic, impulsive offenders have personality profiles characteristic of Scandinavian early-onset male alcoholics with antisocial traits, who have been also referred to as type 2 alcoholics.

CSF biochemistries, glucose metabolism, and diurnal activity rhythms in alcoholic, violent offenders, fire setters, and healthy volunteers.

BACKGROUND: There is an extensive literature describing a central serotonin deficit in alcoholic, impulsive, violent offenders and fire setters. In the present study, we investigated biochemical concomitants of impulsivity and aggressiveness, and the physiological consequences of reduced central serotonin turnover. METHODS: Forty-three impulsive and 15 nonimpulsive alcoholic offenders and 21 healthy volunteers were studied in the forensic psychiatry ward of a university psychiatric department. The subjects underwent lumbar punctures and oral glucose and aspartame challenges, and their diurnal activity rhythm was measured with physical activity monitors. Discriminant function analyses were used to investigate psychophysiological and biochemical concomitants of aggressive and impulsive behaviors. RESULTS: Alcoholic, impulsive offenders with antisocial personality disorder had low mean cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) and corticotropin levels and high mean CSF testosterone concentrations. Compared with healthy volunteers, they showed increased physical activity during the daytime. Alcoholic, impulsive offenders with intermittent explosive disorder had a low mean CSF 5-HIAA concentration and blood glucose nadir after an oral glucose challenge, and desynchronized diurnal activity rhythm. Healthy volunteers had mean CSF 5-HIAA concentrations that were intermediate between those of alcoholic, impulsive and nonimpulsive offenders. Alcoholic, nonimpulsive offenders had a significantly higher mean CSF 5-HIAA concentration than all the other groups, including healthy volunteers. CONCLUSIONS: In the present sample, a low CSF 5-HIAA concentration was primarily associated with impulsivity and high CSF testosterone concentration, with aggressiveness or interpersonal violence.

Marked reduction in the number of platelet-tritiated imipramine binding sites in geriatric depression.

The number (Bmax) and affinity (Kd) of platelet-tritiated imipramine binding sites was determined in young and middle-aged controls 50 years of age and younger (n = 25), elderly normal controls over 60 years of age (n = 18), patients who fulfilled DSM-III criteria for major depression who were under 50 years of age (n = 29), patients who fulfilled DSM-III criteria for major depression who were 60 years of age and older (n = 19), and patients who fulfilled both DSM-III criteria for primary degenerative dementia and National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease (n = 13). Both groups of depressed patients (under 50 and over 60 years of age) exhibited significant reductions (decreases 42%) in the number of platelet-tritiated imipramine binding sites with no change in affinity, when compared with their age-matched controls. There was little overlap in Bmax values between the elderly depressed patients and their controls. The patients with probable Alzheimer's disease showed no alteration in platelet-tritiated imipramine binding. There was no statistically significant relationship between postdexamethasone plasma cortisol concentrations and tritiated imipramine binding. These results indicate that platelet-tritiated imipramine binding may have potential utility as a diagnostic adjunct in geriatric depression, and moreover that the reduction in the number of platelet-tritiated imipramine binding sites is not due to hypercortisolemia.

A critical evaluation of cysteamine as a tool to deplete somatostatin in the rat central nervous system.

The wide central nervous system (CNS) distribution of somatostatin (SRIF) as well as the well documented reduction in SRIF concentration in the cerebral cortex in patients with Alzheimer's disease have served as an impetus for studies of this peptide's neurobiological role in the brain. These studies were designed to evaluate the efficacy of centrally administered cysteamine (CYS) as a tool to deplete SRIF in the hypothalamus (HYP) and extrahypothalamic brain areas. Somatostatin was measured by RIA in the frontal cortex (COR), hippocampus (HIP), and HYP in rats after seven daily infusions of CYS into unilateral cannulae stereotaxically positioned into either the lateral ventricle (LV; 300 micrograms/2 microliters) or the dorsal HIP (100 micrograms/2 microliters), and after single (300 mg/kg) or daily (100 mg/kg) sc injections; rats were killed 4 or 24 h after the last injection. After LV infusions, the SRIF concentration was significantly reduced only in the HYP (35% at 4 h and 27% at 24 h). After HIP infusions, the SRIF concentration was significantly reduced only in the HYP at 4 h (23%); no reductions were observed at 24 h. Both a single and repeated sc administrations of CYS reduced SRIF in the HYP only 24 h after treatment (54% and 50%, respectively). Acute sc CYS reduced SRIF in the COR (23%) and the HYP (29%) 4 h after treatment; repeated sc CYS reduced SRIF in the COR (25%) and the HYP (63%). Although the reduction of SRIF in the HYP was increased by repeated sc dosing, the reduction of extrahypothalamic SRIF by sc CYS was relatively small in magnitude and was not enhanced by repeated dosing. These results suggest that CYS is not an ideal tool for depletion of extrahypothalamic SRIF after sc or CNS administration and, moreover, raise serious questions about studies in which behavioral or endocrine alterations after CYS treatment were attributed to specific actions on SRIF-containing neurons.

Apparent seasonal rhythms in hypothalamic neuropeptides in rats without photoperiod changes.

An apparent seasonal or circannual rhythm in the hypothalamic content of CRF, TRH, neurotensin, and neuromedin N has been observed in 12 separate monthly coherts (n = 10@ or 130 total) adult, male Sprague-Dawley rats obtained at the same time each month from a single commercial supplier and held under constant (12:12) photoperiod conditions since birth. Both annual and 4-month (terannual) harmonics can be statistically discerned in these apparent rhythms, which exhibit cycles containing concentration changes up to 3-fold the lowest levels across the year (CRF increases 390%, TRH increases 173%, neurotensin increases 136%, and neuromedin N increases 150%). Hypothalamic somatostatin did not exhibit these statistically significant robust rhythms nor did any peptide in regions outside the hypothalamus. These data indicate that a mechanism allowing enhanced or diminished physiological availability of these regulatory neuropeptides at different times of the year may exist and may display distinct cycles even in the absence of normal photoperiod cues. Possible regulatory responses of pituitary receptor populations for these hypothalamic peptides must be considered. As certain of these neuropeptides also appear to be altered in the cerebrospinal fluid of patients with major depression or schizophrenia, similar hypothalamic cyclic changes may underly psychiatric symptoms with seasonal periodicity.

Release of corticotropin-releasing factor from rat brain regions in vitro.

In addition to its endocrine action in the anterior pituitary, corticotropin-releasing factor (CRF) also appears to play a role in regulating higher central nervous system function(s). To investigate further the role of CRF in brain, a specific RIA was used to measure in vitro CRF release during incubation of various rat brain regions in Krebs-Henseleit buffer. Increasing the potassium concentration to 56 mM resulted in a 10-fold increase in CRF release from minced hypothalamus. However, the high K+ concentrations had no effect in the presence of calcium-free buffer containing 1 mM EGTA. Scorpion venom also stimulated CRF release in a calcium-dependent manner. CRF-like immunoreactivity was detected in extrahypothalamic brain regions using RIA and HPLC. Significant calcium-dependent CRF release from the rat amygdala and midbrain was observed in response to 56 mM K+ or scorpion venom. These results indicate that depolarizing agents induce the release of CRF-like immunoreactivity not only from the hypothalamus but also from other rat brain regions and lend further support to the hypothesis that CRF may be a neurotransmitter or neuromodulator in the central nervous system.

Role for brain corticotropin-releasing factor in the weight-reducing effects of chronic fenfluramine treatment in rats.

Fenfluramine is an amphetamine derivative which is used as a weight-reducing agent in the treatment of obesity. It has been postulated that fenfluramine affects brain serotonin (5HT) neurons resulting in decreased food intake and altered autonomic outflow which, in turn, increases metabolism. CRF decreases food intake and, in addition, has been demonstrated to reduce body weight in genetically obese rats through selective activation of sympathetic and inhibition of parasympathetic outflows. Because 5HT is a potent CRF secretagogue, we tested the hypothesis that the weight-reducing effects of fenfluramine administration may be mediated, in part, through altered CRF secretion. Chronic fenfluramine treatment (1-24 mg/kg sc, twice daily, 4 days) resulted in a dose-dependent decrease in hypothalamic CRF concentration at 30 min after the final drug injection and was accompanied by a significant reciprocal increase in plasma corticosterone concentration. These data suggest that the decrease in hypothalamic CRF was a consequence of increased CRF secretion. These changes in hypothalamic CRF and plasma corticosterone correlated with brain fenfluramine levels. In contrast, high dose fenfluramine treatment significantly increased hippocampus, midbrain, and spinal cord CRF concentrations whereas levels in cerebral cortex, caudate putamen, thalamus, pons/medulla, and cerebellum were unaffected. There was no effect of this fenfluramine treatment protocol on regional brain TRH or neurotensin concentrations. In keeping with the well known development of tolerance to the weight-reducing effects of fenfluramine, chronic fenfluramine treatment resulted in lesser increases in corticosterone secretion than after acute treatment. Whereas weight loss observed after chronic fenfluramine treatment was associated with stimulation of hypothalamic-pituitary-adrenocortical hormone secretion, the weight-recovery phase after cessation of drug treatment was associated with decreased levels of plasma corticosterone. These data, demonstrating fenfluramine-induced alterations in brain CRF and plasma corticosterone, suggest that CRF may represent an important endogenous transmitter which mediates the weight-reducing effects of the drug.

Cerebrospinal fluid neuropeptides in dementia.

Cerebrospinal fluid concentrations of corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH) and somatostatin (SRIF) were measured in 77 female inpatients with moderate to extreme dementia and in 17 elderly female controls. Both multi-infarct (MID) and Alzheimer-type (SDAT) demented patients had equally elevated CSF CRH and TRH but not SRIF levels as compared with the controls. This elevation was, however, not seen in patients with simple dementia while it was most prominent in those exhibiting marked depressive symptoms. It is concluded that depression rather than dementia itself may be associated with CSF CRH and TRH elevation in elderly patients with cognitive impairment.

Cerebrospinal fluid thyrotropin-releasing hormone concentrations in alcoholics and normal controls.

Alterations in hypothalamic-pituitary-thyroid axis function have been reported in alcoholism. Blunting of the thyroid-stimulating hormone (TSH) response to thyrotropin-releasing hormone (TRH) occurs in approximately 25% of alcoholic patients. Using a sensitive radioimmunoassay that allows TRH itself to be measured in cerebrospinal fluid (CSF), CSF concentrations of TRH were measured in alcoholics and normal controls. There was no significant difference in TRH concentrations between the groups. However, among the controls there was a significant correlation between CSF concentrations of the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and CSF concentrations of TRH. This correlation was lacking in the alcoholics. These findings are of interest because basic neurobiological studies have reported that TRH and serotonin are co-localized in certain neurons in the rat central nervous system.

Cerebrospinal fluid TRH immunoreactivity in anorexia nervosa.

Central nervous system (CNS) thyrotropin-releasing hormone (TRH) activity is of interest in patients with anorexia nervosa. First, anorexics have peripheral thyroid abnormalities that appear to be related to weight and nutritional status. Second, CNS TRH activity may effect many other physiologic systems that are known to be disturbed in patients with anorexia nervosa. We found that anorexic patients, when both underweight and studied after attaining goal weight, had significantly reduced CSF TRH concentrations in comparison to controls. These data suggest that weight gain or increased caloric intake, in contrast to its large effect on peripheral thyroid function, has relatively little effect on CNS TRH activity. The reason for reduced CSF TRH in goal weight anorexics is not known but could be trait related, a persistent defect slow to normalize after weight gain, or related to these patients still being at a weight lower than controls. Finally, in terms of CSF TRH concentrations, this study suggests that anorexia nervosa has a different pathophysiology than major depressive disorder.

CSF corticotropin-releasing factor (CRF) in Alzheimer's disease: its relationship to severity of dementia and monoamine metabolites.

The concentration of corticotropin-releasing factor-like immunoreactivity (CRF-LI) in the cerebrospinal fluid (CSF) of 15 probable Alzheimer's disease (AD) patients with mild to moderate dementia and 10 neurologically normal age-matched controls was examined. There were no significant alterations in the mean CSF CRF-LI concentration in AD compared to controls. However, in the AD group, CSF CRF-LI correlated significantly with the global neuropsychological impairment ratings, suggesting that greater cognitive impairment was associated with lower CSF CRF-LI concentrations. There was a significant reduction in the CSF concentration of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in the AD patients, and there was a positive correlation between the concentration of CRF-LI and 5-HIAA in CSF. This latter finding suggests that serotoninergic neuronal systems may interact with CRF-containing neurons.