A cell-ECM mechanism for connecting the ipsilateral eye to the brain.

Information about features in the visual world is parsed by circuits in the retina and is then transmitted to the brain by distinct subtypes of retinal ganglion cells (RGCs). Axons from RGC subtypes are stratified in retinorecipient brain nuclei, such as the superior colliculus (SC), to provide a segregated relay of parallel and feature-specific visual streams. Here, we sought to identify the molecular mechanisms that direct the stereotyped laminar targeting of these axons. We focused on ipsilateral-projecting subtypes of RGCs (ipsiRGCs) whose axons target a deep SC sublamina. We identified an extracellular glycoprotein, Nephronectin (NPNT), whose expression is restricted to this ipsiRGC-targeted sublamina. SC-derived NPNT and integrin receptors expressed by ipsiRGCs are both required for the targeting of ipsiRGC axons to the deep sublamina of SC. Thus, a cell-extracellular matrix (ECM) recognition mechanism specifies precise laminar targeting of ipsiRGC axons and the assembly of eye-specific parallel visual pathways.

Pharmacokinetics, systemic toxicity, thermoregulation and acute behavioural effects of 25CN-NBOMe.

N-(2-methoxybenzyl)phenethylamines (NBOMes) are a family of potent 5-HT2A agonists containing substances emerging on the illicit drug market as a replacement for N,N-diethyllysergamide (LSD). Despite the increasing use of NBOMes for diagnostic, research and recreational purposes, only a limited number of studies have focussed on their in vivo effect. Here, we investigated pharmacokinetics, systemic toxicity, thermoregulation in individually and group-housed animals, and acute behavioural effects after subcutaneous administration of 2,5-dimethoxy-4-(2-((2-methoxybenzyl)amino)ethyl)benzonitrile (25CN-NBOMe; 0.2, 1, and 5 mg/kg) in Wistar rats. Drug concentration peaked 1 h after the administration of 5 mg/kg in both blood serum and brain tissue with a half-life of 1.88 and 2.28 h, respectively. According to Organisation for Economic Co-operation and Development 423 toxicity assay, the drug is classified into category 3 with a lethal dose of 300 mg/kg and an estimated LD50 value of 200 mg/kg. Histological examination of organs collected from rats injected with the lethal dose revealed subtle pathological changes, highly suggestive of acute cardiovascular arrest due to malignant arrhythmia. Altered thermoregulation after 5 mg/kg was demonstrated by reduced body temperature in individually housed rats (p < 0.01). Behavioural effects assessed by the Open Field test and Prepulse Inhibition of Startle Response revealed that the two lower doses (0.2 and 1 mg/kg) caused a reduction in locomotor activity (p < 0.01), increased anxiety (p < 0.05) and 5 mg/kg additionally impaired sensorimotor gating (p < 0.001). In summary, 25CN-NBOMe readily passes the blood-brain barrier and exhibits a moderate level of toxicity and behavioural effect comparable with other NBOMes.

Circadian alignment in a foster mother improves the offspring's pathological phenotype.

KEY POINTS: In mammals, the mother-offspring interaction is essential for health later in adulthood. The impact of altered timing and quality of maternal care on the offspring's circadian system was assessed using a cross-strain fostering approach. Better maternal care facilitated the development of amplitudes of Bmal1 clock gene expression in the central clock, as well as the clock-driven activity/rest rhythm, and also its entrainment to the external light/dark cycle. Worse maternal care impaired entrainment of the central clock parameters in the Wistar rat during the early developmental stages. Better maternal care remedied the dampened amplitudes of the colonic clock, as well as cardiovascular functions. The results provide compelling evidence that the circadian phenotype of a foster mother may affect the pathological symptoms of the offspring, even if they are genetically programmed. ABSTRACT: In mammals, the mother-offspring interaction is essential for health later in adulthood. Maternal care is determined by the circadian phenotype of the mother. The impact of altered timing and quality of maternal care on the circadian system was assessed using a cross-strain fostering approach, with 'abnormal' (i.e. circadian misaligned) care being represented by spontaneously hypertensive rats (SHR) and 'normal' care by Wistar rats. The SHR mothers worsened synchrony of the central clock in the suprachiasmatic nuclei with the light/dark cycle in Wistar rat pups, although this effect disappeared after weaning. The maternal care provided by Wistar rat mothers to SHR pups facilitated the development of amplitudes of the Bmal1 expression rhythm in the suprachiasmatic nuclei of the hypothalamus, as well as the clock-driven activity/rest rhythm and its entrainment to the external light/dark cycle. The peripheral clocks in the liver and colon responded robustly to cross-strain fostering; the circadian phenotype of the Wistar rat foster mother remedied the dampened amplitudes of the colonic clock in SHR pups and improved their cardiovascular functions. In general, the more intensive maternal care of the Wistar rat mothers improved most of the parameters of the abnormal SHR circadian phenotype in adulthood; conversely, the less frequent maternal care of the SHR mothers worsened these parameters in the Wistar rat during the early developmental stages. Altogether, our data provide compelling evidence that the circadian phenotype of a foster mother may positively and negatively affect the regulatory mechanisms of various physiological parameters, even if the pathological symptoms are genetically programmed.

Development and entrainment of the colonic circadian clock during ontogenesis.

Colonic morphology and function change significantly during ontogenesis. In mammals, many colonic physiological functions are temporally controlled by the circadian clock in the colon, which is entrained by the central circadian clock in the suprachiasmatic nuclei (SCN). The aim of this present study was to ascertain when and how the circadian clock in the colon develops during the perinatal period and whether maternal cues and/or the developing pup SCN may influence the ontogenesis of the colonic clock. Daily profiles of clock genes Per1, Per2, Cry1, Cry2, Rev-erbα, Bmal1, and Clock expression in the colon underwent significant modifications since embryonic day 20 (E20) through postnatal days (P) 2, 10, 20, and 30 via changes in the mutual phasing among the individual clock gene expression rhythms, their relative phasing to the light-dark regime, and their amplitudes. An adult-like state was achieved around P20. The foster study revealed that during the prenatal period, the maternal circadian phase may partially modulate development of the colonic clock. Postnatally, the absence and/or presence of rhythmic maternal care affected the phasing of the clock gene expression profiles in pups at P10 and P20. A reversal in the colonic clock phase between P10 and P20 occurred in the absence of rhythmic signals from the pup SCN. The data demonstrate ontogenetic maturation of the colonic clock and stress the importance of prenatal and postnatal maternal rhythmic signals for its development. These data may contribute to the understanding of colonic function-related diseases in newborn children.

Effects of synthetic cathinone naphyrone in the conditioned place preference test - Evidence of its addictive potential.

Naphyrone, also known as NRG-1, is a novel psychoactive substance (NPS), a cathinone with stimulatory properties available on the grey/illicit drug market for almost a decade. It is structurally related to infamously known powerful stimulants with the pyrovalerone structure, such as alpha-pyrrolidinovalerophenone (α-PVP) or methylenedioxypyrovalerone (MDPV) that are labeled as a cheap replacement for cocaine and other stimulants. Despite the known addictive potential of α-PVP and MDPV, there are no studies directly evaluating naphyrone's addictive potential e.g., in conditioned place preference (CPP) test or using self-administration. Therefore, our study was designed to evaluate the addictive potential in a CPP test in male Wistar rats and compare its effect to another powerful stimulant with a high addictive potential - methamphetamine. Naphyrone increased time spent in the drug-paired compartment with 5 and 20 mg/kg s.c. being significant and 10 mg/kg s.c. reaching the threshold (p = 0.07); the effect was comparable to that of methamphetamine 1.5 mg/kg s.c. The lowest dose, naphyrone 1 mg/kg s.c., had no effect on CPP. Interestingly, no dose response effect was detected. Based on these data, we are able to conclude that naphyrone has an addictive potential and may possess a significant risk to users.

Diverse development and higher sensitivity of the circadian clocks to changes in maternal-feeding regime in a rat model of cardio-metabolic disease.

Spontaneously hypertensive rats (SHR) develop cardiovascular and metabolic pathology in adulthood when their circadian system exhibits significant aberrances compared with healthy control rats. This study was aimed to elucidate how the SHR circadian system develops during ontogenesis and to assess its sensitivity to changes in maternal-feeding regime. Analysis of ontogenesis of clock gene expression rhythms in the suprachiasmatic nuclei, liver and colon revealed significant differences in SHR compared with Wistar rats. In the suprachiasmatic nuclei of the hypothalamus (SCN) and liver, the development of a high-amplitude expression rhythm selectively for Bmal1 was delayed compared with Wistar rat. The atypical development of the SHR circadian clocks during postnatal ontogenesis might arise from differences in maternal behavior between SHR and Wistar rats that were detected soon after delivery. It may also arise from higher sensitivity of the circadian clocks in the SHR SCN, liver and colon to maternal behavior related to changes in the feeding regime because in contrast to Wistar rat, the SHR SCN and peripheral clocks during the prenatal period and the hepatic clock during the early postnatal period were phase shifted due to exposure of mothers to a restricted feeding regime. The maternal restricted feeding regime shifted the clocks despite the fact that the mothers were maintained under the light/dark cycle. Our findings of the diverse development and higher sensitivity of the developing circadian system of SHR to maternal cues might result from previously demonstrated differences in the SHR circadian genotype and may potentially contribute to cardiovascular and metabolic diseases, which the animal model spontaneously develops.