Psilocybin induces dose-dependent changes in functional network organization in rat cortex

Psilocybin produces an altered state of consciousness in humans and is associated with complex spatiotemporal changes in brain networks. Given the emphasis on rodent models for mechanistic studies, there is a need for characterization of the effect of psilocybin on brain-wide network dynamics. Previous rodent studies of psychedelics, using electroencephalogram, have primarily been done with sparse electrode arrays that offered limited spatial resolution precluding network level analysis, and have been restricted to lower gamma frequencies. Therefore, in the study, we used electroencephalographic recordings from 27 sites (electrodes) across rat cortex (n=6 male, 6 female) to characterize the effect of psilocybin (0.1 mg/kg, 1 mg/kg, and 10 mg/kg delivered over an hour) on network organization as inferred through changes in node degree (index of network density) and connection strength (weighted phase-lag index). The removal of aperiodic component from the electroencephalogram localized the primary oscillatory changes to theta (4-10 Hz), medium gamma (70-110 Hz), and high gamma (110-150 Hz) bands, which were used for the network analysis. Additionally, we determined the concurrent changes in theta-gamma phase-amplitude coupling. We report that psilocybin, in a dose-dependent manner, 1) disrupted theta-gamma coupling [p<0.05], 2) increased frontal high gamma connectivity [p<0.05] and posterior theta connectivity [p≤0.049], and 3) increased frontal high gamma [p<0.05] and posterior theta [p≤0.046] network density. The medium gamma frontoparietal connectivity showed a nonlinear relationship with psilocybin dose. Our results suggest that high-frequency network organization, decoupled from local theta-phase, may be an important signature of psilocybin-induced non-ordinary state of consciousness.

Intravenous psilocybin attenuates mechanical hypersensitivity in a rat model of chronic pain

There is a renewed interest in psychedelic drugs as potential therapeutic agents for the treatment of psychiatric disorders. In particular, psilocybin has shown promise for the treatment of refractory depression1 and major depressive disorder2, and has also been explored as a treatment for tobacco and alcohol abuse3,4. However, despite suggestive evidence5,6, there has been no systematic study to investigate the effectiveness of psilocybin in attenuating indices of chronic pain. To address this gap, we investigated the effect of psilocybin on mechanical hypersensitivity and thermal hyperalgesia in a well-established rat model of formalin-induced, centralized chronic pain7,8 and demonstrate that a single intravenous bolus administration of psilocybin can attenuate mechanical hypersensitivity for 28 days.

Dose effect of gestational ethanol exposure on placentation and fetal growth

INTRODUCTION

Prenatal ethanol exposure compromises fetal growth by impairing placentation. Invasive trophoblastic cells, which mediate placentation, express the insulin-IGF regulated gene, aspartyl-asparaginyl β-hydroxylase (ASPH), which has a critical role in cell motility and invasion. The aims of this study were to characterize effects of ethanol on trophoblastic cell motility, and assess ethanol dose-dependent impairments in placentation and fetal development.

METHODS

Pregnant Long Evans dams were fed with isocaloric liquid diets containing 0%, 8%, 18% or 37% ethanol (caloric content) from gestation day (GD) 6 to GD18. Fetal development, placental morphology, density of invasive trophoblasts at the mesometrial triangle, as well as placental and mesometrial ASPH and Notch-1 protein expression were evaluated. Directional motility of control and ethanol-exposed HTR-8/SVneo cells was assessed by ATP Luminescence-Based assay.

RESULTS

Severity of fetal growth impairment correlated with increasing doses of ethanol. Ethanol exposure produced dose-dependent alterations in branching morphogenesis at the labyrinthine zone, and inhibited physiological transformation of maternal arteries. ASPH and Notch-1 protein expression levels were reduced, corresponding with impairments in placentation.

DISCUSSION

Prenatal ethanol exposure compromises fetal growth and placentation in a dose-responsive manner. Ethanol's adverse effects on placental development are mediated by: (1) altered branching morphogenesis in labyrinthine zone; (2) suppression of invasive trophoblastic precursor cells; and (3) inhibition of trophoblastic cell adhesion and motility, corresponding with reduced ASPH and Notch-1 protein expression.

Precision-cut slice culture method for rat placenta

Primary trophoblasts, placental explants, and cell line cultures are commonly used to investigate placental development, physiology, and pathology, particularly in relation to pregnancy outcomes. Organotypic slice cultures are increasingly used in other systems because they maintain the normal three-dimensional tissue architecture and have all cell types represented. Herein, we demonstrate the utility of the precision-cut placental slice culture model for studying trophoblastic diseases.

Risperidone in chronic schizophrenia: a detailed audit, open switch study and two-year follow-up of patients on depot medication

Little information exists on the medium- to long-term outcome of switching patients with schizophrenia from traditional depot to atypical oral antipsychotic agents. By detailed clinical audit, we identified a representative group of 102 patients of an Irish psychiatric service with DSM-IV chronic schizophrenia and on depot neuroleptics for a mean of 15 years. Of 69 eligible to participate, 33 entered a 6-month switch study of risperidone, with limited follow-up of consenters and non-consenters at 1 and 2 years. At 6 months, 23 of 33 were still on risperidone and had small significant improvements in clinical and extrapyramidal side effects, QOL and adjunct medication measures over baseline. At 12 months, 19 of 33 were still on risperidone, reducing to 13 of 33 at 2 years. At 2 years, of 32 surviving consenters to switch, 19 had suffered clinically detrimental events and were no longer on risperidone, compared to none of the 33 surviving non-consenters, who were all still on depot. These findings suggest that switching from depot to risperidone may encounter high rates of refusal and attrition subsequent to switch. While a majority of switched patients may improve to least 6 months, audit plus switch may have clinically unfavourable effects on others over a 2-year follow-up period [corrected].

The last mental hospital

The public mental hospital system was created in part because many mentally ill people were being held in prisons and jails. Support for those hospitals waned over time, however, and by the time they had degenerated into "snake pits" a consensus was reached to close them down. Unfortunately, they were not replaced with adequate community mental health resources, so as the hospitals have emptied, the prisons and jails have filled, partly with the mentally ill. That is the destructive reason for the growth of prison psychiatry in this country: the prison has become the last mental hospital. The constructive one has been a new emphasis on bringing psychiatric treatment to a previously neglected population: people who have committed serious violence, whether because of Axis I mental illnesses or Axis II character disorders. Unfortunately, four inter-related, mutually reinforcing nationwide trends threaten to reinforce that destructive development and vitiate the constructive one.

Targeted expression of calcitonin gene-related peptide to osteoblasts increases bone density in mice

The neuropeptide calcitonin gene-related peptide (CGRP) is concentrated in fine sensory nerve endings innervating all tissues, including bone. CGRP inhibits osteoclasts, stimulates insulin-like growth factor I and inhibits tumor necrosis factor alpha production by osteoblasts in vitro. To investigate the role of CGRP in bone in vivo, mice were engineered to express CGRP in osteoblasts by placing the human CGRP gene under the control of the rat osteocalcin promoter (Ost-CGRP tg+ mice). Calvaria cultures from transgene positive (tg+), but not tg- mice, produced bioactive CGRP. Trabecular bone density and bone volume, determined by peripheral quantitative computed tomography and bone histomorphometry, respectively, were higher in tg+ than tg- littermates. This increase in bone volume was associated with an increased bone formation rate. Trabecular bone density decreased in tg+ mice as a result of ovariectomy, but remained higher than in sham tg- mice. Targeting CGRP to osteoblasts appears to favor the establishment of a higher trabecular bone mass in mice.

Endothelin-I-mediated vasoconstriction: specific blockade by verapamil

The capacity of three vasodilators that act by distinct mechanisms to reverse endothelin-I-mediated vasoconstriction was studied in 11 healthy nonsmoking male subjects (mean age +/- SEM, 26 +/- 2 years; mean weight +/- SEM, 74 +/- 2 kg) by use of brachial artery infusion and forearm strain-gauge plethysmography. Isoproterenol (cyclic adenosine monophosphate-mediated vasodilation), sodium nitroprusside (cyclic guanosine monophosphate-mediated vasodilation), and verapamil (L-type calcium channel blocker) were compared for capacity to reverse endothelin-I-mediated increase in forearm vascular resistance (FVR). Endothelin-I infusion increased FVR 1.9-fold in the control state. Isoproterenol infusion decreased FVR with or without concurrent endothelin-I infusion; however, at comparable isoproterenol infusion rates, endothelin-I increased FVR similar to the control state (for 5 ng/min isoproterenol, endothelin-I increased FVR 1.85-fold; for 12.5 ng/min isoproterenol, endothelin-I increased FVR 2.03-fold). Similarly, sodium nitroprusside infusion decreased FVR with or without concurrent endothelin-I infusion; however, at comparable sodium nitroprusside infusion rates the endothelin-I increase in FVR was similar to control (for 0.48 micrograms/min sodium nitroprusside, endothelin-I increased FVR 1.89-fold; for 0.96 micrograms/min sodium nitroprusside, endothelin-I increased FVR 2.36-fold). In contrast, verapamil infusion decreased FVR with or without endothelin-I infusion. At a verapamil infusion rate of 19.1 microns/min, endothelin-I increase in FVR was comparable to control (for 19.1 microns/min verapamil, endothelin-I increased FVR 1.36-fold, less than the 1.0-fold increase in the control state; p < 0.05). Isoproterenol and sodium nitroprusside decreased FVR during concurrent endothelin-I infusion but did not reverse the endothelin-I effect. In contrast, verapamil reversed endothelin-I--induced vasoconstriction to control FVR, suggesting a specific antagonism of endothelin-I--mediated increase in FVR.

Neurological injuries in South Australia: the influence of distance on management and outcome

It has been shown that in at least two Australian states (New South Wales and South Australia), there is a disproportionately high incidence of lethal neurological injuries in country areas. To determine whether any of this increased rural mortality results from geographical remoteness from specialized hospital services, we have studied prospectively a consecutive series of 153 patients with head injuries (140) or spinal injuries (13), who were transferred to Adelaide, South Australia from country centres during a six month period. Distance appeared to be an occasional cause of delay in instituting expert primary treatment. Of 13 deaths, three resulted from potentially remediable causes (intracranial bleeding, airway obstruction), and in two others difficulties in early supportive care may have contributed to death. First aid sometimes had to be administered by lay persons, and appeared to have been occasionally inadequate. Undesirable delay in transfer from accident site to country hospital was recorded in a few cases; in some of these, private transport was used. Distance was an important cause of delay in transferring patients to Adelaide, since 77% of patients had to travel in excess of 50 km. Thirty patients were brought to Adelaide by medical retrieval teams. These teams, which are centrally co-ordinated, have been useful in extending to country areas the specialized techniques of emergency intensive care and less frequently of operative neurosurgery.

Short-term aluminum administration in the rat. Effects on bone formation and relationship to renal osteomalacia

Aluminum may be pathogenic in the osteomalacia observed in some patients receiving hemodialysis. To study the early effects of Al on bone growth, bone formation, mineralization, and resorption were measured during short-term Al exposure in the tibial cortex of pair-fed control (C, n = 10), aluminum-treated (AL, n = 9), subtotally nephrectomized control (NX-C, n = 7), and subtotally nephrectomized aluminum-treated (NX-AL, n = 8) rats using double tetracycline labeling of bone. Animals received 2 mg/d of elemental Al intraperitoneally for 5 d/wk over 4 wk. Total bone and matrix (osteoid) formation, periosteal bone and matrix formation, and periosteal bone and matrix apposition fell by 20% in AL from C, P less than 0.05 for all values, and by 40% in NX-AL from NX-C, P less than 0.01 for all values. Moreover, each measurement was significantly less in NX-AL than in AL, P less than 0.05 for all values. Osteoid width did not increase following aluminum administration in either AL or NX-AL. Resorption surface increased from control values in both AL and NX-AL; also, resorptive activity at the endosteum was greater in NX-AL than in NX-C, P less than 0.05. Thus, aluminum impairs new bone and matrix formation but does not cause classic osteomalacia in the cortical bone of rats whether renal function is normal or reduced. These findings may represent either a different response to aluminum administration in cortical bone as contrasted to trabecular bone or an early phase in the development of osteomalacia. Aluminum may increase bone resorption and contribute to osteopenia in clinical states associated with aluminum accumulation in bone.

Legionnaires' disease in South Australia. Four case reports

Four severe cases of Legionnaires' disease are described. In addition to multilobar pneumonia with respiratory failure, involvement of the central nervous, cardiovascular, renal, hepatic and coagulation systems had occurred. Adult respiratory distress syndrome complicated respiratory management. Early development of acute renal failure was associated with a poor prognosis. Erythromycin was the most commonly used antibiotic. Review of stored pathological material from patients who died from unidentified pneumonias enabled confirmation of the existence of Legionnaires' disease in Australia in 1974.