Modulation of olfactory-driven behavior by metabolic signals: role of the piriform cortex.

Olfaction is one of the major sensory modalities that regulates food consumption and is in turn regulated by the feeding state. Given that the olfactory bulb has been shown to be a metabolic sensor, we explored whether the anterior piriform cortex (aPCtx)-a higher olfactory cortical processing area-had the same capacity. Using immunocytochemical approaches, we report the localization of Kv1.

Nutrient Sensing: Another Chemosensitivity of the Olfactory System.

Olfaction is a major sensory modality involved in real time perception of the chemical composition of the external environment. Olfaction favors anticipation and rapid adaptation of behavioral responses necessary for animal survival. Furthermore, recent studies have demonstrated that there is a direct action of metabolic peptides on the olfactory network.

Cellular and molecular cues of glucose sensing in the rat olfactory bulb.

In the brain, glucose homeostasis of extracellular fluid is crucial to the point that systems specifically dedicated to glucose sensing are found in areas involved in energy regulation and feeding behavior. Olfaction is a major sensory modality regulating food consumption. Nutritional status in turn modulates olfactory detection.

Modulation of olfactory sensitivity and glucose-sensing by the feeding state in obese Zucker rats.

The Zucker fa/fa rat has been widely used as an animal model to study obesity, since it recapitulates most of its behavioral and metabolic dysfunctions, such as hyperphagia, hyperglycemia and insulin resistance. Although it is well established that olfaction is under nutritional and hormonal influences, little is known about the impact of metabolic dysfunctions on olfactory performances and glucose-sensing in the olfactory system of the obese Zucker rat. In the present study, using a behavioral paradigm based on a conditioned olfactory aversion, we have shown that both obese and lean Zucker rats have a better olfactory sensitivity when they are fasted than when they are satiated.

Olfactory preference conditioning changes the reward value of reinforced and non-reinforced odors.

Olfaction is determinant for the organization of rodent behavior. In a feeding context, rodents must quickly discriminate whether a nutrient can be ingested or whether it represents a potential danger to them. To understand the learning processes that support food choice, aversive olfactory learning and flavor appetitive learning have been extensively studied.

A physiological increase of insulin in the olfactory bulb decreases detection of a learned aversive odor and abolishes food odor-induced sniffing behavior in rats.

Insulin is involved in multiple regulatory mechanisms, including body weight and food intake, and plays a critical role in metabolic disorders such as obesity and diabetes. An increasing body of evidence indicates that insulin is also involved in the modulation of olfactory function. The olfactory bulb (OB) contains the highest level of insulin and insulin receptors (IRs) in the brain.

Olfaction under metabolic influences.

Recently published work and emerging research efforts have suggested that the olfactory system is intimately linked with the endocrine systems that regulate or modify energy balance. Although much attention has been focused on the parallels between taste transduction and neuroendocrine controls of digestion due to the novel discovery of taste receptors and molecular components shared by the tongue and gut, the equivalent body of knowledge that has accumulated for the olfactory system, has largely been overlooked. During regular cycles of food intake or disorders of endocrine function, olfaction is modulated in response to changing levels of various molecules, such as ghrelin, orexins, neuropeptide Y, insulin, leptin, and cholecystokinin.

Changes in rat olfactory detection performance induced by orexin and leptin mimicking fasting and satiation.

Numerous peripheral and hypothalamic peptides control food intake. Among these signals are orexin, an orexigenic molecule released into the olfactory bulb by centrifugal hypothalamic fibres and leptin, an anorexigenic molecule that is released peripherally and can pass through the blood-brain barrier. In the present study, we injected either orexin or leptin, intracerebroventricularly, and their effect on olfactory performance was evaluated in two groups of rats, using a behavioral paradigm based on conditioned olfactory aversion.

Fasting increases and satiation decreases olfactory detection for a neutral odor in rats.

Olfaction plays a fundamental role in feeding behavior, but changes in olfactory acuity according to feeding states have never been precisely demonstrated in animals. The present study assesses the olfactory detection performance of fasted or satiated rats placed under a strictly controlled food-intake regimen. We did this using a conditioned odor aversion (COA) protocol which induced in rats an almost total aversion to an ISO-odorized drink at 10(-5) (1 microl in 100 ml of water).

Anosmin-1, defective in the X-linked form of Kallmann syndrome, promotes axonal branch formation from olfactory bulb output neurons.

The physiological role of anosmin-1, defective in the X chromosome-linked form of Kallmann syndrome, is not yet known. Here, we show that anti-anosmin-1 antibodies block the formation of the collateral branches of rat olfactory bulb output neurons (mitral and tufted cells) in organotypic cultures. Moreover, anosmin-1 greatly enhances axonal branching of these dissociated neurons in culture.

Early postnatal Müller cell death leads to retinal but not optic nerve degeneration in NSE-Hu-Bcl-2 transgenic mice.

Topographically localized over-expression of the human Bcl-2 protein in retinal glial Müller cells of a transgenic mice (line 71) leads to early postnatal apoptotic Müller cell death and retinal degeneration. Morphological, immunohistological and confocal laser microscopic examination of transgenic and wild-type retinas were achieved on paraffin retinal sections, postnatally. Apoptosis occurs two to three days earlier in the internal nuclear layer of transgenic retinae, than in wild-type littermates.

Anosmin-1 is a regionally restricted component of basement membranes and interstitial matrices during organogenesis: implications for the developmental anomalies of X chromosome-linked Kallmann syndrome.

Kallmann syndrome is a developmental disease characterized by gonadotropin-releasing hormone (GnRH) deficiency and olfactory bulb hypoplasia. The gene underlying the X chromosome-linked form, KAL-1, has been identified for several years, yet the pathogenesis of the disease is not understood. By immunohistofluorescence and immunoelectron microscopy, we establish that the KAL-1 encoded protein, anosmin-1, is a transient and regionally restricted component of extracellular matrices during organogenesis in man.

Spatiotemporal patterns of expression of extracellular matrix molecules in the developing and adult rat olfactory system.

Using immunocytochemical methods, we have examined extensively the spatial and temporal patterns of expression of three extracellular matrix molecules-laminin, fibronectin, and type IV collagen-in the embryonic, postnatal (days 2 and 11) and adult rat olfactory system. The study started at embryonic day 14 when olfactory fibres and their associated migrating cells course through the nasal mesenchyme. From embryonic day 14 to the adult, a sheet-like pattern of labelling for laminin, fibronectin and type IV collagen was observed along the basal surface of the olfactory epithelium and around the telencephalon.

Time-course of apoptosis in the olfactory epithelium of rainbow trout exposed to a low copper level.

Copper at low doses is known to specifically induce olfactory neuron death in fish olfactory epithelium. Using light and electron transmission microscopy, we have investigated the features and the time-course of receptor cell death in rainbow trout exposed for 15 days to 20 mug Cu(2+)/l. Ultrastructural observations demonstrate that degenerating cells, which included both mature and immature neurons, exhibited morphological changes characteristic of a cell death by apoptosis.

[An unusual complication of cervicofacial lift: paralysis of the external branch of the accessory spinal nerve].

Paralysis of the lateral branch of the accessory nerve is an extremely rare lesion during cervico-facial facelift. Based on 3 detailed and published personal cases observed over a period of 15 years, the authors review the literature, revealing a total of 9 cases over a period of 30 years, but other cases have probably not been published. Their review reveals the following points.

Effects of chronic low-level copper exposure on ultrastructure of the olfactory system in rainbow trout (Oncorhynchus mykiss).

This study investigated the effects of a chronic exposure to a low level of copper on cell populations of the olfactory system in yearling rainbow trout. Fish were sacrificed after 15, 30 and 60 days of copper exposure. Transmission electron microscopy was used to describe the sequence of subcellular changes occurring in three tissues, the sensory epithelium, the olfactory nerve and the olfactory bulb.

X-ray microanalysis of calcium containing organelles in resin embedded tissue.

The localization of calcium in cell organelles at the electron microscope level is often achieved through cytochemical techniques, and verified by X-ray microanalysis. Various methods have been used to cytochemically detect calcium or calcium-binding sites: calcium loading, calcium substitution by strontium, barium, or even lead, and calcium precipitation by oxalate, phosphate, fluoride, or pyroantimonate. Their results may have heuristic value, particularly in preliminary studies of poorly known cell types.

Problems in the immunolocalization of type IX collagen in fetal calf cartilage using a monoclonal antibody.

Monoclonal antibodies were prepared against the pepsin-resistant fragments (X1-X3) of bovine type IX collagen. One of the five hybridomas that gave a positive reaction in an enzyme-linked immunosorbent assay was selected (H1a) for structural analysis and immunolocalization of type IX collagen. The location of the epitope for H1a was deducted from immunoblots and electron microscopic observations after rotary shadowing.

[The pendular nipple. Technic of correction].

In some women, particularly of African origin, the nipple may droop to the point of justifying the name of "pendular nipple". The author proposes a triangular resection of the areola and nipple maintained by the point with resection of its length. A previously raised graft is applied to the raw surface to give a normal appearance and colour.

Quantitative X-ray microanalysis of calcium with the Camebax-TEM system in frozen, freeze-substituted and resin-embedded tissue sections. Application to molluscan glio-interstitial granules.

The relevance of the continuum method for a quantitative X-ray microanalysis of epon embedded tissue sections in the particular conditions offered by the Camebax-TEM system was tested and an improved model of specimen holder is proposed. The absolute calcium concentration [Ca] of membrane-bound intracellular glio-interstitial granules was determined by X-ray microanalysis in transmission electron microscopy of Mytilus retractor muscle. The Ca peak and background values were measured by the wavelength-dispersive spectrometer of the Camebax; the mass thickness of the section was recorded simultaneously with an added energy-dispersive detector.

The development of glio-interstitial tissue in Mytilus retractor muscle depends on Na+-Ca2+ antagonism.

The development of glio-interstitial cell processes has been studied by quantitative electron microscopy in the anterior byssal retractor muscle of mussels kept in various artificial sea-waters. After 20 days, the number of glio-interstitial processes per unit area of muscle section from animals adapted to diluted sea-water (700 mosM) is not significantly different from the control (1100 mosM) but it is almost doubled in mussels adapted to concentrated sea-water (1400 mosM). The diluted sea-water has a high [Ca2+]/[Na+]2 molar ratio (6.