Brain peptides (second of two parts)

Autoimmunity Related to Adipsic Hypernatremia and ROHHAD Syndrome

Specific antibody responses to subfornical organs, including Na_x antibody, have been reported in patients with adipsic hypernatremia of unknown etiology who do not have structural lesions in the hypothalamic–pituitary gland. The subfornical organ, also referred to as the window of the brain, is a sensing site that monitors sodium and osmotic pressure levels. On the other hand, ROHHAD syndrome is a rare disease for which the etiology of the hypothalamic disorder is unknown, and there have been some reports in recent years describing its association with autoimmune mechanisms. In addition, abnormal Na levels, including hypernatremia, are likely to occur in this syndrome. When comparing the clinical features of adipsic hypernatremia due to autoimmune mechanisms and ROHHAD syndrome, there are similar hypothalamic–pituitary dysfunction symptoms in addition to abnormal Na levels. Since clinical diagnoses of autoimmunological adipsic hypernatremia and ROHAD syndrome might overlap, we need to understand the essential etiology and carry out precise assessments to accurately diagnose patients and provide effective treatment. In this review, I review the literature on the autoimmune mechanism reported in recent years and describe the findings obtained so far and future directions.

Korean hand acupressure for motion sickness in prehospital trauma care: a prospective, randomized, double-blinded trial in a geriatric population

Patients with trauma or medical illnesses transported to the hospital by ambulance have a frequent incidence of motion sickness. Because the administration of drugs in the ambulance is prohibited by law in Austria, the noninvasive Korean hand acupressure point at K-K9 may be an alternative against nausea and vomiting. We enrolled 100 geriatric patients with minor trauma, randomizing them into a K-K9 group and a sham acupressure group. We recorded visual analog scores (VAS) for nausea and for the patient's overall satisfaction with the treatment, hemodynamic variables, and peripheral vasoconstriction. In the K-K9 group, a significant (P < 0.01) increase in nausea was recorded in all cases: from VAS of 0 mm to 25 +/- 6 mm. A similarly significant (P < 0.01) increase was registered in the sham group: from VAS of 0 mm to 83 +/- 8 mm. However, at the time of arrival in the hospital, nausea scores were significantly different between the K-K9 group and the sham group (P < 0.01). Although all patients had been vasoconstricted at the emergency site before treatment, there was a significant difference (P < 0.01) between groups with regard to the number of vasoconstricted patients at the hospital (4 and 46 constricted and dilated, respectively, in the K-K9 group versus 48 and 2 constricted and dilated, respectively, in the sham group). On arrival in the hospital, a significant difference (P < 0.01) in heart rate was noted between the K-K9 group and the sham group (65 +/- 6 bpm versus 98 +/- 8 bpm). The patients' overall satisfaction with the provided care was significantly higher (P < 0.01) in the K-K9 group (19 +/- 9 mm VAS) than in the sham group (48 +/- 12 mm VAS). Neither group experienced a significant change in blood pressure. K-K9 stimulation was an effective and simple treatment for nausea during emergency care and significantly improved patient satisfaction.

IMPLICATIONS

Korean hand acupressure at the K-K9 point was effective in reducing nausea and subjective symptoms of motion sickness in emergency trauma transport of patients at high risk of motion sickness.

Role of ghrelin polymorphisms in obesity based on three different studies

OBJECTIVE

Associations between preproghrelin DNA variants and obesity-related phenotypes were studied in 3004 subjects from the Québec Family Study (QFS), the HERITAGE Family Study (HERITAGE), and the Swedish Obese Subjects (SOS) Study.

RESEARCH METHODS AND PROCEDURES

Body mass index (BMI), fat mass (FM) from underwater weighing, and abdominal fat from computerized tomography were measured. The ghrelin polymorphisms were identified by polymerase chain reaction.

RESULTS

Arg51Gln QFS subjects (n = 6) had lower ghrelin concentrations (p = 0.007) than Arg51Arg subjects (n = 14). White preproghrelin Met72Met subjects in HERITAGE had the lowest BMI (p = 0.020), and those in the QFS cohort had the lowest FM (p < 0.001). Met72 carrier status (Met72+) was associated with lower FM (p = 0.026) and higher insulin-like growth factor-1 levels (p = 0.019) among blacks. Met72Met QFS subjects had less visceral fat (p = 0.002) and a lower fasting respiratory quotient (p = 0.037). HERITAGE Met72+ white subjects also showed lower exercise respiratory quotient (p = 0.030) and higher maximal oxygen uptake (p = 0.023). Furthermore, the prevalence of Met72+ was higher (19.2%; p < 0.05) in SOS subjects whose BMI was < or =25 kg/m(2) than in those with BMI >25 kg/m(2) (14.8%). SOS Met72+ obese women had a lower (11.4%; p = 0.032) prevalence of hypertension than noncarriers (23.9%).

DISCUSSION

Arg51Gln mutation was associated with lower plasma ghrelin levels but not with obesity. The preproghrelin Met72 carrier status seems to be protective against fat accumulation and associated metabolic comorbidities.

Physiological neuroendocrinology of peptides, steroids and other hormones in cerebrospinal fluid

Cerebrospinal fluid acts as a conduit in neuroendocrine regulation. Valid assessment of normal cerebrospinal fluid levels of peptides, steroids and other hormones requires clarification of reference concentrations in control patients and normal volunteers. Awareness of factors which may alter neuronal activity and, in turn, the relative composition of cerebrospinal fluid constituents is essential to the accurate sampling and hormonal analysis of cerebrospinal fluid.

Effect of vagotomy on hyperactivity and increased dopamine turnover induced by intraperitoneal administration of thyrotropin-releasing hormone

Thyrotropin-releasing hormone (TRH) injected intraperitoneally at doses of 10 mg/kg and 20 mg/kg induced marked hyperactivity in rats. Although regional levels of brain dopamine and its metabolites (DOPAC and HVA) in vagotomized rats did not differ from those in sham-operated controls, the (DOPAC + HVA)/dopamine ratio, an indicator of dopamine turnover, was significantly higher in the nucleus accumbens of TRH-treated sham-operated rats than that in untreated sham-operated controls. TRH injection induced hyperactivity only in sham-operated rats and not in subdiaphragmatic bilaterally vagotomized rats. Similarly, bilateral vagotomy completely abolished the TRH-induced increases in dopaminergic turnover in the nucleus accumbens. These results suggest that the dopaminergic system in the nucleus accumbens is involved in hyperactivity induced by TRH, and that TRH mainly affects peripheral receptors. The vagal nerve may be the major pathway from the visceral organs to the brain involved in the etiology of hyperactivity.

Substance P increases cochlear blood flow without changing cochlear electrophysiology in rats

Carotid artery infusions of substance P yielded reductions in systemic blood pressure and elevations in cochlear blood flow (CoBF), measured via laser Doppler flowmeter, with no alterations in cochlear action potentials or cochlear microphonics in Wistar-Kyoto rats. Additionally, direct micro-infusions of substance P into the anterior inferior cerebellar artery, which contributes to the local vascular perfusion of the cochlea, yielded elevations in CoBF with no changes in systemic blood pressure. Pretreatment with a specific substance P receptor antagonist, ([D-Pro2,D-Trp7,9]SP) via the carotid artery or the anterior inferior cerebellar artery, diminished subsequent substance P-induced vascular responses. These results suggest that endogenous substance P, like other vasoactive peptides, may interact with a substance P-specific receptor population in the cochlea and may therefore participate in the ongoing regulation of CoBF. These findings also support the premise that vasodilatory hormones, along with vasoconstrictive agents, may be involved in the autoregulation of CoBF.

Direct in vivo gene transfer to ependymal cells in the central nervous system using recombinant adenovirus vectors

To evaluate the potential for adenovirus-mediated central nervous system (CNS) gene transfer, the replication deficient recombinant adenovirus vectors Ad.RSV beta gal (coding for beta-galactosidase) and Ad-alpha 1AT (coding for human alpha 1-antitrypsin) were administered to the lateral ventricle of rats. Ad.RSV beta gal transferred beta-galactosidase to ependymal cells lining the ventricles whereas Ad-alpha 1AT mediated alpha 1-antitrypsin secretion into the cerebral spinal fluid for 1 week. These observations, together with beta-galactosidase activity in the globus pallidus and substantia nigra following stereotactic administration of Ad.RSV beta gal to the globus pallidus, suggest that adenovirus vectors will be useful for CNS gene therapy.

Immunoreactive beta-endorphin levels in cerebrospinal fluid of children with acute lymphoblastic leukemia: relationship with glucocorticoid therapy and neurological complications

Neurological disorders, such as seizures, are not infrequently associated with anti-leukemic therapy. It has been hypothesized that a disrupted peptidergic transmission between neurons could be the cellular basis of the neurological dysfunction. Since endogenous opioids have been recently found to alter neuronal function and possess anticonvulsant properties, the cerebrospinal fluid (CSF) immunoreactive beta-endorphin levels in children with Acute Lymphoblastic Leukemia (ALL) during chemotherapy and cranial irradiation have been studied. Twenty-seven children, 2 at low, 20 at medium and 5 with high risk ALL, undergoing prophylactic treatment for meningeal leukemia, entered the study. Sequential lumbar punctures with introduction of MTX combined with oral prednisone therapy were performed; each lumbar puncture sample was collected and assayed for immunoreactive beta-endorphin. All the patients studied showed a biphasic profile of the peptide with the minimum levels reached during the induction (days 14-28) and the maximum levels detected at the end of the intensification chemotherapy (days 49-55). In the 3 groups the beta-endorphin decrease corresponded to the period of prednisone therapy; the increase was concomitant with the suspension of oral glucocorticoids. 3 patients showed tonic-clonic seizures which coincided with the lowest cerebrospinal fluid beta-endorphin levels and, in the follow-up, 13 out of 27 patients displayed EEG abnormalities. From these findings a relationship between cerebrospinal fluid beta-endorphin concentrations and neuronal excitability in patients with ALL can be suggested. It is also evidenced that oral glucocorticoid therapy has profound inhibitory effects on central beta-endorphin levels.

Suckling stimulation test for neonatal tremor

The response of neonatal tremor to a suckling stimulation test was investigated in 102 healthy neonates born at full term. In 84 the tremor resolved immediately; none had hypocalcaemia and only one had mild hypoglycemia. Eighteen in whom the tremor continued had either hypocalcaemia (n = 13) or hypoglycaemia (n = 5).

Neuroregulatory effects of nicotine

The impact of nicotine on the central nervous system is, in an important sense, neuroregulatory, with cascading effects on physiological and biochemical function as well as on behavioral activity. Accordingly, the neurotransmitter and neuroendocrine effects of nicotine constitute a critical part of its biological action, which includes reinforcing as well as pathophysiological consequences. This review focuses on nicotine's effects on cholinergic and non-cholinergic nicotine receptors and on the responses of catecholamines, monoamines, hypophyseal hormones, and cortisol. The contribution of critical variables, such as timing and duration of neuroregulator release and the patterns that make up the total response, is still largely unknown, particularly with regard to the effects of environmental context, history of nicotine use, and mode of administration. The evidence suggests that by altering the bioavailability of the above-listed neuroregulators, nicotine serves as a pharmacological "coping response", providing immediate though temporary improvement in affect or performance in response to environmental demands. Much of what is known to date is based on studies involving the administration of agonists and antagonists under different environmental conditions. Newer technological approaches such as autoradiography and positron emission tomography show potential for determining the neuroregulatory patterns involved and specifying nicotine's locus of action relevant to its behavioral and physiological effects.

Interactions between the blood-brain barrier and endogenous peptides: emerging clinical implications

The effects of peptides on brain function suggest therapeutic and pathologic roles for these substances. Many peptides cross the blood-brain barrier (BBB) by transmembrane diffusion as a function of their lipid solubilities. Other peptides, such as the enkephalins, Tyr-MIF-1, vasopressin-related peptides, and peptide T-like peptides, are transported by carrier-mediated systems. Passage is influenced by aging, stress, lighting, drugs, amino acids, and neurotoxins. Disruption of the BBB results in complex changes in the blood and CSF levels of peptides. Peptides influence the passage of glucose, amino acids, and inorganic acids and may affect the integrity of the BBB. Peptide-BBB interactions have been suggested to play direct roles in dialysis dementia and maple syrup urine disease; they may be expected to be involved in other disorders of the CNS.

Can barbiturate anaesthesia cure infantile spasms?

Five patients with infantile spasms and hypsarrhythmia and one with Lennox-Gastaut syndrome were treated with brief thiopentone anaesthesia as the primary treatment of infantile spasms. Thiopentone (30 mg/kg) was given intravenously and burst suppression was reached in EEG in three patients by this dose. The results were disappointing. In three patients a transient beneficial effect on spasms and hypsarrhythmia was seen, but all patients relapsed. Three other patients had anaesthesia for surgery. The spasms ceased and hypsarrhythmia disappeared dramatically, and the effect was permanent. The possible mechanisms of the therapeutic effect are discussed. It seems advisable to give anaesthesia and surgery prior to steroid treatment in any case where the both are needed.

Saturable transport of peptides across the blood-brain barrier

Peptides can be transported across the blood-brain barrier by saturable transport systems. One system, characterized with radioactively labeled Tyr-MIF-1 (Tyr-Pro-Leu-Gly-amide), is specific for some of the small peptides with an N-terminal tyrosine, including Tyr-MIF-1, the enkephalins, beta-casomorphin, and dynorphin (1-8). Another separate system transports vasopressin-like peptides. The choroid plexus has at least one system distinguishable from those above that is capable of uptake and possibly transport of opiate-like peptides. The possibility of saturable transport of other peptides has been investigated to a varying degree. Specificity, stereo-specificity, saturability, allosteric regulation, modulation by physiologic and pharmacologic manipulations, and noncompetitive inhibition have been demonstrated to occur in peptide transport systems and suggest a role for them in physiology and disease.

Reversal of pentobarbital-induced narcosis by thyrotropin-releasing hormone (TRH) in dogs

A growing body of evidence suggests that thyrotropin-releasing hormone (TRH), and endogenous brain tripeptide, produces behavioral excitation in a variety of mammalian species. This study evaluated the cardiopulmonary and antidepressant response to a single intravenous (i.v.) bolus of TRH in sodium pentobarbital (33 mg.kg-1) anesthetized dogs. TRH (0.5 and 1 mg) produced a significant dose-dependent decrease in sleeping time (33% and 51%, respectively) when compared to i.v. vehicle (1 ml of 0.9% NaCl)-treated animals. Of interest was the finding that the high (1 mg), but not the low (0.5 mg) dose of TRH significantly (P less than 0.01) increased mean arterial pressure and heat rate. In addition, i.v. TRH (1 mg) significantly (P less than 0.01) decreased tidal volume. A trend toward increased respiratory frequency in TRH-treated dogs was noted, this difference, however, did not reach statistical significance. In conclusion, the results of this study support the view that TRH, and endogenous brain hormone, may have an important clinical application in cases where stimulation of the central nervous system is required.

Urotensin I-like immunoreactivity in amacrine cells of the goldfish retina

Urotensin I-like immunoreactivity (UILI), in different localization from that of corticotropin releasing factor-like immunoreactivity (CRFLI), in the goldfish retina has been demonstrated by means of radioimmunoassay, high-performance liquid chromatography (HPLC) and immunohistochemistry. Radioimmunoassay showed 350 +/- 40 pg/mg prot. of UILI in goldfish retina extracts. The immunoreactive material present in the retina was also characterized by reversed phase HPLC. Some of the UILI co-eluted with synthetic carp UI, though the HPLC experiments suggested the existence of other UILI substance(s) with less hydrophobicity than synthetic UI. By immunohistochemistry, UILI and CRFLI were seen in different amacrine cells of the goldfish retina. It is suggested that UI may be involved in the fish visual transmission system together with CRF and other neuropeptides.

Brain cholecystokinin and vasoactive intestinal polypeptide: immunoreactivity in rabbits with hepatic coma

Recent studies have suggested that decreased excitatory neurotransmission in the brain may contribute to the overall neural inhibition which characterizes the syndrome of hepatic encephalopathy (HE), and that vasoactive intestinal polypeptide (VIP) and cholecystokinin (CCK) may promote neural excitation in the brain. To determine if brain levels of these neuropeptides are altered in HE, measurements were made of the concentrations of immunoreactive VIP (iVIP) and immunoreactive CCK (iCCK) in cerebral cortex, cerebellum and hypothalamus isolated from normal rabbits and rabbits with galactosamin-induced hepatic coma. Hepatic coma was associated with reduced concentrations of iVIP, small molecular weight iCCK and large molecular weight iCCK in the cerebral cortex but not in the cerebellum or hypothalamus. These findings are compatible with decreased VIP- and CCK-mediated neural excitation occurring in the syndrome of HE.

Beta-endorphins in acute myocardial infarction

The endogenous peptide B-endorphin (B-EP) is closely connected with different aspects of homeostasis, behavior, and in particular with the perception of pain. The purpose of this study was to investigate the correlation between: the level of plasma B-EP and the intensity of pain in acute myocardial infarction (AMI); and the B-EP and specific enzymes for AMI serum glutamic oxolo-acetic transferase, lactate dehydrogenase, and creatine phosphokinase and some stress hormones (cortisol, growth hormone). Twenty-six patients hospitalized in the CCU for acute MI were studied during the first 72 hours from the onset of symptoms. Seven normal subjects served as controls. Blood was taken for hormone and B-EP evaluation before treating the patients by opiates. Plasma B-EP levels were determined using the protocol of the Immunonuclear Corporation (Stillwater, MN). Statistical analysis of the results showed: Nonsignificant differences between B-EP levels of all MI patients and control group. Unaltered B-EP levels in patients with acute MI suffering from moderate pain. Significant differences in drop of B-EP in the group with most severe pain (p less than 0.025). A tendency toward decreased B-EP in patients suffering from more prolonged pain (greater than 6 hours). Significant negative correlation was shown between B-EP and chest pain intensity (0-4 graduation) (r = 0.8, p less than 0.01); lactate dehydrogenase (r = 0.7, p less than 0.01); serum glutamic oxolo-acetic transferase (r = 0.6, p less than 0.01); creatine phosphokinase (r = 0.6, p less than 0.05; plasma cortisol level (r = 0.5, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

A technique for repeated sampling of CSF from the anesthetized rat

A method for repeatedly sampling cerebrospinal fluid (CSF) from anesthetized rats is described. The technique reliably and quickly yields blood-free samples of CSF and requires supplies that are commonly available. Samples as large as 250 microliter can be collected in a few minutes. There is no apparent malaise even when CSF is withdrawn once every three days for two weeks. This technique offers an alternative to surgical cannulation for sampling of CSF from the rat.

Neuropeptides: ACTH-peptides in dementia

Studies on the treatment of demented patients with ACTH neuropeptides are reviewed. The discussion is restricted to ACTH4-10 and an orally active peptide, the modified ACTH4-9 fragment: H-Met (O2)-Glu-His-Phe-D-Lys-Phe-O (Org 2766). The first part of the review concentrates on data from animal pharmacology and basic and human studies which have relevance for the clinical effects shown in demented patients. The second part concerns clinical studies in man. Own results from a placebo-controlled dose finding study on the treatment of 156 PDSD patients with Org 2766 are presented. Org 2766 was in this study found to have a significant therapeutic effect in patients with PDSD measured mainly on the basis of SCAG total, although the effect was found to be rather small (average 4 points improvement on SCAG total). Post hoc analyses demonstrated that effects were clinically relevant for only 25 per cent of the patients. Analyses of SCAG factor scores indicated an effect on cognitive function and somatic function. The study failed to show clear dose-response relationship. However, before a final conclusion on the efficacy of Org 2766 can be reached the results must be confirmed by others.

Corticotropin-releasing factor and intraocular pressure

The effect of centrally administered corticotropin-releasing factor (CRF) on intraocular pressure (IOP) was investigated using the technique of ventriculocisternal perfusion. Various amounts of ovine CRF (0.01, 0.033, 0.1 and 0.33 micrograms/min) were perfused in conscious, male New Zealand albino rabbits for 1 hour. At a dose level of 0.1 or 0.33 micrograms/min, CRF caused an acute IOP decrease of 2.5 mmHg, which lasted for 30 min. Perfusions with CRF at 0.033 micrograms/min or higher caused delayed ocular hypotension, which began 20 hours after the perfusion and lasted for 2 days. Bolus intravenous injection of 3.3 micrograms CRF did not cause any IOP changes. These findings demonstrate that CRF can cause a centrally mediated IOP response. Superior cervical ganglionectomy eliminated the acute, not the delayed, CRF effect on IOP, indicating the involvement of ocular sympathetic nerves in the acute IOP effect.

Aging and the blood-brain barrier: changes in the carrier-mediated transport of peptides in rats

Age-related changes in the brain's saturable, specific, carrier-mediated transport system for the small, N-tyrosinated peptides Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) and methionine-enkephalin (Met-Enk) were studied in Fischer 344 rats aged 4 and 26 months. These studies showed statistically significant differences between the two age groups for both the Tmax (transport maximum) [3.22 +/- 0.013 nmol/min/g (young rats, mean +/- S.E.M.) vs 2.41 +/- 0.009 nmol/min/g (age rats)] and T50 (the amount required to achieve 50% of that maximum) [84.9 +/- 1.0 nmol/g (young) vs 65.1 +/- 0.60 nmol/g (aged)]. The T50:Tmax ratio was nearly equal to the two groups: 26.4 (young) vs 26.9 (aged), consistent with the uncompetitive type of inhibition indicative of alterations in the substrate-carrier complex. In addition, blood concentrations of Tyr-MIF-1-like immunoactivity were nearly doubled in aged rats (3.24 +/- 0.373 vs 1.67 +/- 0.0904 pM/ml), while blood concentrations of Met-Enk-like immunoactivity and brain concentrations of immunoactive Tyr-MIF-1 and Met-Enk showed no statistically significant difference between age groups. Thus, a carrier-mediated system responsible for the transport of peptides across the blood-brain barrier undergoes changes with aging.

Modulation of lordosis behaviour in the female rat by corticotropin releasing factor, beta-endorphin and gonadotropin releasing hormone in the mesencephalic central gray

A possible functional relationship between corticotropin-releasing factor (CRF) and opiate peptide neuronal systems (beta-endorphin, dynorphin1-17 and Met-enkephalin) and their interactions with gonadotropin releasing hormone (GnRH) in the mesencephalic central gray (MCG) for the regulation of lordosis behaviour was assessed in ovariectomized, oestrogen-treated and oestrogen-progesterone-treated female rats. Lordosis behaviour triggered by male mounting was inhibited in a dose-dependent fashion by CRF microinfused into the MCG in both oestrogen-treated and oestrogen-progesterone-treated female rats. This CRF-induced inhibition of lordosis could be overcome by a pre-infusion of naloxone or anti-beta-endorphin-globulin (anti-beta-end-G) directly into the MCG but not by anti-Met-enkephalin globulin (anti-enk-G) or anti-dynorphin1-17 globulin (anti-dynor-G). Supporting data indicate that the facilitation of lordosis behaviour induced by treatment with naloxone or anti-beta-end-G alone but not with anti-enk-G or anti-dynor-G may be due to enhanced GnRH release. This results from the action of these substances in overcoming the inhibition of GnRH secretion mediated specifically by beta-endorphin but not by Met-enkephalin or dynorphin1-17 in the MCG. These studies together with previous data showing that GnRH can overcome the abolition of lordosis by beta-endorphin in the MCG, indicate a close relationship between beta-endorphin (but not Met-enkephalin or dynorphin) and GnRH systems in the MCG in the control of lordosis behaviour. Thus, the inhibition of lordosis by CRF and the complete reversal of this blockade by naloxone or anti-beta-end-G may suggest that CRF could enhance the release of beta-endorphin from fibres in the MCG; beta-endorphin then inhibits lordosis by inhibiting the release of GnRH. However, a direct inhibitory effect of CRF on GnRH release is also likely since anti-CRF-gamma-globulin (anti-CRF-G) infused into the MCG produced a long-lasting facilitation of lordosis which can be blocked by an antagonist analogue of GnRH; in addition, previous studies have shown that GnRH infused into the MCG completely overcame the CRF-induced abolition of lordosis and potentiated lordosis to high levels. These results suggest that there may be functional neuroanatomical relationships between CRF, beta-endorphin and GnRH neuronal systems in the MCG in the control of female sexual behaviour. Neither Met-enkephalin nor dynorphin1-17 appear to participate in such mechanisms.

Differentiation between Crohn's disease and other inflammatory conditions by electron microscopy

The authors previously have demonstrated axonal necrosis of autonomic nerves in the surgically resected ilea of patients with Crohn's disease both in grossly normal ileal resection margins and in diseased areas. The present study of ileal stomal biopsies was carried out to obviate the possibility that the observed axonal damage might be related to the prolonged surgical manipulations required for ileal resection. The authors present studies of biopsies of ileal stomas and of small bowel from patients with Crohn's disease and various control disorders, including ulcerative colitis. Stomal biopsies were fixed immediately after they were obtained. Widespread, severe axonal necrosis of autonomic nerves was present in all Crohn's disease specimens, regardless of the patient's clinical status or the gross or routine microscopic evaluation of the same specimen. Controls either had no necrosis or displayed a minor degree of focal necrosis involving single axons. The authors conclude that Crohn's disease is accompanied by a severe and extensive necrosis of gut axons, and that such electron microscopic findings may serve to differentiate Crohn's disease from other inflammatory disorders.

Evidence for a 'paravascular' fluid circulation in the mammalian central nervous system, provided by the rapid distribution of tracer protein throughout the brain from the subarachnoid space

The protein tracer, horseradish peroxidase (HRP), was infused into the lateral cerebral ventricles or subarachnoid space of anesthetized cats and dogs after insertion of a cisternal cannula to permit drainage of cerebrospinal fluid (CSF) and tracer solution. The intracerebral distribution of the tracer was then determined by light microscopy of serial brain sections after postinfusion intervals of 4 min-2 h. For the localization of HRP, sections were incubated with diaminobenzidine (DAB) or the much more sensitive chromogen, tetramethylbenzidine (TMB). The TMB reaction showed a consistent 'paravascular' distribution of tracer reaction product, within the perivascular spaces (PVS) around large penetrating vessels and in the basal laminae around capillaries, far beyond the termination of the PVS. After infusion of HRP over 4 min, arterioles were surrounded by the tracer, but capillaries and venules were usually less densely demarcated; by 6 min, however, the intraparenchymal microvasculature was outlined in toto throughout the forebrain and brainstem. Electron microscopy of sections incubated in DAB after 10 or 20 min HRP circulation confirmed the paravascular location of the reaction product, which was also dispersed throughout the extracellular spaces (ECS) of the adjacent parenchyma. Our results demonstrate that solutes in the CSF have access to the ECS throughout the neuraxis within minutes via fluid pathways paralleling the intraparenchymal vasculature. The rapid paravascular influx of HRP could be prevented by stopping or diminishing the pulsations of the cerebral arteries by aortic occlusion or by partial ligation of the brachiocephalic artery. The exchange of solutes between the CSF and the cerebral ECS has generally been attributed to diffusion, however, HRP enters the neuraxis along the intraparenchymal microvasculature far more rapidly than can be explained on this basis. This apparent convective tracer influx may be facilitated by transmission of the pulsations of the cerebral arteries to the microvasculature. We postulate that a fluid circulation through the CNS occurs via paravascular pathways.

Opiate modulation of glucose turnover in dogs

We examined the effect of opiate infusion and of opiate blockage on glucose turnover in the basal state, using isotope dilution techniques in trained conscious dogs (n = 5). After a primed-continuous infusion of 3-3H glucose to steady state specific activity (90 minutes), infusion of one of the following was given: D-met2 pro5 enkephalinamide (DMPE), a potent morphine-like opiate, 0.5 mus g/kg/min; naloxone, an opiate antagonist, 1.25 mg followed by 10 mus g/min; or saline control. Infusion of DMPE led to a fall in glucose from 92 +/- 3 to 87 +/- 3 mg/dL by 60 minutes (P less than 0.05), associated with a rise in glucose utilization (Rd) from 3.0 +/- 0.4 to 3.9 +/- 0.6 mg/kg/min by 30 minutes (P less than 0.05); a transient rise in glucose production (Ra; from 3.2 +/- 0.4 to 4.3 +/- 0.4 mg/kg/min; P less than 0.05). Changes in counterregulatory hormones did not account for these findings; insulin was unchanged during all infusions; glucagon showed small late rises at 75 minutes during both DMPE and naloxone infusion; cortisol rose by 30 and 15 minutes, respectively, of DMPE and naloxone infusion; epinephrine rose transiently after 5 minutes of naloxone but was unchanged during DMPE, and norepinephrine was unchanged throughout. Saline infusion had no effects on any of these indices. We conclude that a potent opiate with morphine-like effects (DMPE) can lower glucose in dogs by enhancing peripheral glucose utilization independently of hormonal changes.

Cerebrospinal fluid cholecystokinin, bombesin and somatostatin in schizophrenia and normals

Cerebrospinal fluid from 31 normals and two groups of phenomenologically similar schizophrenics (n = 72) were collected by identical methods. Radioimmunoassay of CSF was carried out for somatostatin, bombesin, and cholecystokinin. One group of schizophrenics had increased baseline somatostatin and cholecystokinin, and decreased bombesin. No CSF gradient effect was found for the peptides nor were their levels affected by probenecid or pimozide treatment. An inverse correlation was found between bombesin and psychosis rating. Intercorrelation between the peptides and HVA, 5-HIAA, and MHPG were not significant.

Permeability of the blood-brain barrier to neuropeptides: the case for penetration

Evidence that peptides can cross the blood-brain barrier (BBB) is reviewed. Penetration is suggested by the observations that blood levels correlate with cerebrospinal fluid levels for many peptides and that peripheral administration of peptides results in effects on the CNS. Passage is confirmed by experiments involving administration of a peptide (immunoactive or radioactive) in one compartment and identification of its appearance in the other, supported by such methods as selective labeling, cross-reactivity with highly specific antibodies, and chromatography. The degree of passage varies among peptides and their analogs. The major route of passage is probably by a non-competitive, non-saturable mechanism, wih the physicochemical characteristics of the peptide (e.g. lipophilicity, charge, molecular weight, and protein binding) determining the degree of passage. A competitive transport mechanism also exists for some peptides. Penetration of the BBB via large pores or by pinocytosis does not appear to be of major importance for peptides. Permeability of the BBB to peptides, but not to the larger iodinated albumin, is affected by intraperitoneal administration of aluminum, apparently by an increase in the permeability of the membrane to lipophilic materials.

Bombesin and substance P modulate peripheral sympathetic and cardiovascular activity

The vascular and cardiac effects of bombesin and substance P were evaluated in a "pithed rat preparation" in order to study the cardiovascular effects of these neuropeptides in the absence of the central nervous system control mechanisms. Bombesin (0.7, 7.0 and 70 nmol/kg) produced dose-dependent increases in mean arterial blood pressure (MAP): +6 +/- 1, +11 +/- 2 (p less than 0.05) and +22 +/- 2 mm Hg (p less than 0.01), respectively, when injected IV into the pithed rat. Heart rate (HR) responses to bombesin (0.7-70 nmol/kg) were also increased in a dose-dependent manner: +14 +/- 6, +28 +/- 5 (p less than 0.05) and +45 +/- 3 (p less than 0.05) beats/min (bpm), respectively. The blood pressure (BP) and HR responses to bombesin were diminished but not completely abolished by pretreatment with 1 mg/kg of either the beta-adrenergic receptor blocker propranolol or the H1-histamine receptor antagonist pyrilamine. Substance P similarly caused a dose-dependent increase in MAP: +7 +/- 1 and +38 +/- 7 mm Hg (p less than 0.001), by 0.7 and 700 nmol/kg, respectively, without altering HR. BP responses to sympathetic stimulation were also examined in the pithed rat utilizing electrical stimulation of the spinal cord (1 Hz, 50 V, 1 msec duration for 30 sec). These responses were potentiated by the low doses (0.7 and 7.0 nmol/kg) of bombesin (p less than 0.01) but tended to be suppressed by the highest dose. The HR response to stimulation was significantly reduced: -25 +/- 8 bpm (p less than 0.05) by the highest dose of bombesin (70 nmol/kg) but not with lower doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Causal links between plasma and CSF endorphin levels in stress: vector-ARMA analysis

To explore causal links between vital sign responses and immunoreactive beta-endorphin ("i-BE") rises in blood and CSF during ovine endotoxin stress, we analyzed concurrent i-BE levels in these two compartments by a "vector-ARMA" (= autoregressive moving average) method. This technique--widely used for modeling in other applications--has not to our knowledge been employed to study dynamic relationships of neuropeptides. Log-transformed i-BE levels were first "filtered" by repeated observations ANOVA to confirm significance of rises in both compartments. Next, vector-ARMA methodology was applied to derive an optimal causal model of vital sign changes and i-BE entry into plasma vs. CSF pools. The model indicated that reflux of i-BE from blood into CSF contributed to increases in CSF levels of this hormone. This novel application to neuroendocrinology of this approach illustrates its utility in evaluating changes in one or more neuropeptide levels in multiple compartments to indicate potentially causal relationships.

Vasoactive intestinal polypeptide decreased in cerebrospinal fluid (CSF) in atypical depression. Vasoactive intestinal polypeptide, cholecystokinin and gastrin in CSF in psychiatric disorders

Vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK) and gastrin in the cerebrospinal fluid (CSF) were studied in patients with endogenous depression, non-endogenous depression, mania, schizophrenia and a control group. All patients were classified according to ICD-9 and the group of depressions was further classified according to the Newcastle Rating Scales for depression (Carney et al. 1965) (N-I). In the group of non-endogenously depressed patients, CSF-VIP levels (median 16 pmol/l) were found to be significantly lower than those of controls (median = 32 pmol/l) and endogenous depressives (36 pmol/l). In the non-endogenous group, it appeared that the low CSF-VIP was due to a group of patients who, during a past or present depressive episode, had been diagnosed as suffering from endogenous depression. Moreover, this group was clinically characterized by 'dysphoric/hysterical features', 'reversed diurnal variation' (i.e. worse in the evening), and 'lack of clearly circumscribed episodes'. In many aspects this group seems similar to the atypical depressives described as monoamine oxidase inhibitor responders. Concerning CSF-CCK and CSF-gastrin, no significant differences between the examined groups were demonstrated.

Molecular regulators of brain function: a new view

A working hypothesis is proposed based on two mutually dependent concepts: neurons may be functionally regulated not only by presently known neurotransmitters but by many kinds of informational substances. Known informational substances are considered in categories corresponding to major regulators of the central nervous system, including transmitters, peptides, hormones, "factors" and various proteins. Many new informational substances are being discovered by the application of DNA technology. Alongside neuronal circuitry that forms the basis for conventional neuroanatomy and neurophysiology, and that operates through conventional synaptic junctions, is a system here called parasynaptic, i.e. in "parallel with" synapse-linked circuitry. In the parasynaptic system, informational substances reach specific target cell receptors by diffusion from release points through extracellular fluids. The parasynaptic system has the same degree of selectivity as synaptic circuitry but possesses, in addition, a domain of versatility and plasticity lacking in "hardwired" circuitry; the latter is, however, also influenced by highly potent informational substances in the ambient extracellular fluid.

Neuroregulators and the reinforcement of smoking: towards a biobehavioral explanation

This paper examines findings on the neuroregulatory effects of nicotine in an effort to formulate a unified hypothesis that can explain the remarkable persistence of smoking behavior. Because nicotine alters the bioavailability of several behaviorally active neuroregulators, including acetylcholine, norepinephrine, dopamine, beta-endorphin, and vasopressin, we propose that nicotine is "used" by smokers to produce temporary improvements in performance or affect. Under this formulation, a potential large number of exteroceptive and interoceptive cues unrelated to the nicotine-dependence cycle may serve as discriminative stimuli for smoking, over and above smoking to terminate or avoid withdrawal. The rapid action of nicotine, and its diverse neuroregulatory effects, render it particularly effective as a "coping response" to the demands of daily living. Of special interest in this regard is a biphasic pattern of arousal/catecholaminergic activation followed by cholinergic blockade or beta-endorphin release. Apparently smokers can adjust nicotine intake to enhance these effects selectively, which may add considerably to the appeal of smoking.

Combined high-performance liquid chromatography-radioimmunoassay for the characterization and quantitative measurement of neuropeptides

A method for the extraction, separation, characterization and quantitation of angiotensins, opioid peptides and several other neuropeptides in biological samples is described. Gradient elution in different reversed-phase high-performance liquid chromatographic systems gives high resolution with constant recoveries between 60 and 70%, allows UV detection at 220 nm and is compatible with radioimmunoassay. The method is highly reproducible and applicable to the characterization and quantitative measurement of peptides in the femtomolar range. The practicability of the method is demonstrated for angiotensin peptides in plasma, brain and peripheral organs, as well as for opioid peptides in the heart.

Plasma beta-endorphin concentrations prior to and during pregnancy, in labor, and after delivery

Beta-Endorphin was measured by radioimmunoassay in peripheral plasma of nonpregnant women (58 +/- 2.4 pg/ml, n = 17, mean +/- SE), during the first trimester (47 +/- 2.4 pg/ml, n = 11), the second trimester (33 +/- 1.9, n = 11), and the third trimester (49 +/- 2.7 pg/ml, n = 10) of pregnancy, during early (202 +/- 32 pg/ml, n = 12) and advanced labor (389 +/- 78 pg/ml, n = 10), and 30 to 60 minutes post partum (177 +/- 22 pg/ml, n = 12). Mean plasma levels of beta-endorphin were significantly lower in each trimester of gestation than the levels in nonpregnant control subjects. During labor and the early postpartum period, maternal plasma levels of beta-endorphin were significantly elevated. Furthermore, peripheral plasma levels of beta-endorphin during labor fell from 189 +/- 31 to 97.6 +/- 12 pg/ml (n = 13, p = 0.015) in response to epidural anesthesia, as compared to peripheral plasma concentrations of beta-endorphin of 223 +/- 71 and 193 +/- 47 pg/ml prior to and after injection of saline solution into epidural catheters, respectively, in 10 control subjects. Mean plasma levels of beta-endorphin in patients immediately prior to elective repeat cesarean section who were not in labor (151 +/- 23 pg/ml, n = 15) were significantly higher (p less than 0.005) than the levels in third-trimester control subjects. These data indicate that the pain associated with labor and the psychological stress of anticipating an operation are potent stimuli for the pituitary release of beta-endorphin.

Possible role of the opioid peptides in sleep

The opioid peptide endorphins, enkephalins, and dynorphins--found in brain, pituitary, and gut--are neurohormones involved in the regulation of a number of seemingly diverse biologic activities, including respiration, mood, pain perception, blood pressure, body temperature, and certain visceral responses. When viewed in integrated fashion, however, the spectrum of activities induced by the administration of both the exogenous opiates (e.g. morphine) and the endogenous opioids resembles a natural physiologic state: the sleep state. We propose that the opioid peptides in conjunction with the peptide neurohormone vasopressin are involved in the induction and maintenance of the sleep state. We also propose that the function of sleep is to protect an animal during periods when it is at a selective disadvantage, and we provide evidence to support and integrate both concepts.

Age, environmental factors and prostatic cancer

Although prostatic cancer is evident late in life, pathological evidence suggests this disease is initiated earlier in life. As prostatic cancer is an endocrine associated disease and as adult hormone profiles are established during puberty, it was of interest whether difference in pubertal hormone levels occurred in populations at low or high risk for prostatic cancer. Accordingly we have investigated the hormone profiles in rural Black South African and urban white boys during puberty. It has been suggested that the timing of puberty is modified by environmental factors and that there is a concomitant control of gonadotrophin release and food intake by CNS-peptide hormones. It is therefore postulated that dietary factors during puberty modify the gut-CNS peptide hormones which in turn control the hypothalamic-pituitary-testicular axis. Distinct difference in plasma androgen and gonadotrophins between the two races are in part concordant with a modification of CNS-peptide hormones by environmental factors during puberty.

Beta-endorphin in pregnancy

Concentrations of maternal plasma beta-endorphin (beta-EP) as measured by radioimmunoassay decline during pregnancy, reaching a nadir during the second trimester, rise during labor, remain elevated during the early postpartum period and are increased prior to elective cesarean section in the absence of labor. They decline in response to epidural anesthesia during labor and increase during induction of general but not regional anesthesia for cesarean section. Umbilical venous plasma beta-EP levels are not affected by the route or mode of delivery nor the presence or absence of labor, but rise in conjunction with fetal distress. In the presence of fetal distress, umbilical arterial plasma beta-EP levels appear to rise faster than umbilical venous beta-EP concentrations. Amniotic fluid beta-EP levels are higher during the second than third trimester. These data indicate that peripheral plasma beta-EP concentrations reflect stress in both mother and fetus. In the mother, pregnancy itself does not appear to be stressful, whereas pain associated with labor rather than uterine contractions as such increase plasma beta-EP levels. In the fetus, hypoxia and acidosis effectively raise plasma beta-EP concentrations. The origin and physiologic significance of amniotic fluid beta-EP, which appears to be unrelated to fetal maturity, remain to be established.

Implications of neuropeptides in neurological diseases

Neuropeptides are sufficiently stable to allow valid radioimmunoassay of peptide concentrations in post-mortem human nervous tissue and in human cerebrospinal fluid. Studies have now documented abnormalities of peptide concentrations in degenerative diseases of the brain. Somatostatin concentration is reduced in the hippocampus and neocortex of patients dying with Alzheimer's type dementia. In Huntington's disease, there are reduced concentrations of substance P, met-enkephalin and cholecystokinin in the basal ganglia; in contrast the concentrations of somatostatin and TRH are increased. Immunocytochemical and experimental lesion studies are underway in an attempt to localize the peptide-containing cells affected by these disorders; and the potential role of alterations in neuropeptide function in the pathogenesis, clinical manifestations and therapy of these illnesses is of great interest. Although alterations of CSF peptide concentrations have been reported in a variety of human diseases, interpretation of these results requires knowledge of the origin and disposition of CSF peptides. Future research into the pathology of peptidergic systems will depend on the development of specific peptide antagonists to probe dynamic aspects of peptide function and on the application of the tools of molecular biology, such as specific mRNA assays, to human material.

Interaction between hypothalamic peptides in a superfused pituitary cell system

Recently two hypothalamic releasing factors have been isolated, sequenced and synthesized: corticotropin-releasing factor (CRF) from sheep and rat hypothalami; and growth hormone-releasing factor (GH-RF) from tumors in human pancreas (hpGH-RF) and from rat hypothalami (rhGH-RF). Their biological potencies were tested by various laboratories in vivo and in vitro using rat pituitary cell cultures and the pituitary quarters method. In the present study, we investigated the dynamics of the release of pituitary hormones and the interaction between CRF and hGH-RF and several brain peptides in a pituitary cell-superfusion system. A dose-related ACTH release was found when the cells were superfused with different doses of synthetic CRF. Synthetic hGH-RF44, hGH-RF40, hGH-RF1-29 and purified porcine hypothalamic GH-RF caused similar dose-related releases of GH. In this system, we demonstrated interactions between CRF and vasopressin, CRF and SP, hGH-RF and vasopressin and hGH-RF and PHI-27. We conclude that the control of pituitary hormone secretion is a complex process; several factors may interact with each releasing or inhibiting factor to modulate their effects.

Brain-blood barrier? Yes and no

Ventriculo-cisternal perfusion of horseradish peroxidase (HRP) in the mouse brain has demonstrated that a brain-blood barrier exists at the microvascular endothelium in brain parenchyma but not in the median eminence of the hypothalamus. The brain-blood barrier is similar to the blood-brain barrier in that: tight junctions prevent the movement of protein between endothelial cells, HRP taken into the endothelial cells is directed to lysosomal dense bodies, and, contrary to the literature, a vesicular transendothelial transport of HRP from brain to blood does not occur under normal conditions. The endocytosis of ventricular injected HRP from the abluminal side of the endothelium is demonstrably less than the endocytosis of intravenous injected HRP from the luminal side; hence, the cerebral endothelium expresses a degree of polarity regarding the internalization of its cell surface membrane and extracellular protein. The passage of cerebrospinal fluid-borne or blood-borne HRP between some ependymal cells of the median eminence is not precluded by tight junctions. These patent extracellular channels offer a direct pathway for the exchange of substances between cerebrospinal fluid in the third ventricle and fenestrated capillaries in the median eminence.

Information transfer in biological systems. Part II: Transfer of molecular information through biological membranes. The "reverse-translation"

A theory based on the fluid-mosaic-membrane model is presented to account for the transduction of extracellular molecular information into cells. Binding of a ligand to the external surface of the lipoprotein membrane leads to a specific rearrangement of the intracellular receptor-analogs or to a characteristic deformation of the inner membrane surface and these changes trigger further intracellular events. The saturated and unsaturated fatty acid chains in the membrane have important roles in transferring the extracellular molecular informations. Some similarities between the effects of monoamines, oligo- and polypeptides may be explained on the basis of this model. As a consequence of the model the possible existence of "reverse-translation" is suggested.