Opposing functions of chondroitin sulfate and heparan sulfate during early neuronal polarization

Axon-dendrite polarity of neurons is essential for information processing in the nervous system. Here we studied the functions of chondroitin sulfate (CS) and heparan sulfate (HS) in neuronal polarization using cultured dissociated hippocampal neurons. Immunohistochemical analyses of early cultured neurons indicated the distribution of these glycosaminoglycans to be quite different. While CS epitopes were accumulated in the focal contacts present in axons and cell bodies, those of HS were detected ubiquitously on the cell surface including on dendrites and axons. Treatment with chondroitinase (CHase) ABC, which degrades CS, and knockdown of a CS sulfotransferase, N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (4,6-ST), which is involved in the biosynthesis of oversulfated structures, induced the formation of multiple axons in hippocampal neurons. Time-lapse recordings revealed the multiple axons of CHase ABC-treated neurons to be highly unstable, extending and retracting, repeatedly. CHase ABC-treatments suggested that CS is involved in the formation of phosphorylated focal adhesion kinase-positive focal contacts. Thus, CS may enhance integrin signaling in the nascent axons, supporting axon specification. On the other hand, when neurons were treated with heparitinases that specifically degrade HS, neurons with a single axon increased. The axons of HSase-treated neurons extended steadily and showed almost no retraction. These results suggest that CS stabilizes and HS destabilizes the growth of axons in an opposing manner, contributing to early neuronal polarization.

Effect of a selective agonist for prostaglandin E receptor subtype EP4 (ONO-4819) on the cortical bone response to mechanical loading

The influence of a selective agonist for prostaglandin E receptor subtype EP4 (ONO-4819) on the bone response to mechanical loading was evaluated. Six-month-old female Wistar rats were used and assigned to three groups (n = 12/group): Vehicle administration (EP4-V), low-dose ONO-4819 administration (EP4-L, 3 microg/kg BW), and high-dose ONO-4819 administration (EP4-H, 30 microg/kg BW). ONO-4819 was subcutaneously injected in the back twice a day for 3 weeks. Loads on the right tibia at 39.4 N for 36 cycles at 2 Hz were applied in vivo by 4-point bending every other day for 3 weeks. Whole-body bone mineral content showed a significant difference between EP4-V and EP4-H (P < 0.05). Bone mineral density (BMD) of the total and regional tibia (the region with maximal bending at the central diaphysis) was higher in EP4-H than EP4-V, showing a significant effect of loading (P < 0.001) and ONO-4819 (P < 0.05). BMD of the total femur was higher in EP4-H than EP4-V (P < 0.01) and that of the distal femur was higher in EP4-H than EP4-V (P < 0.001). Histomorphometry of the cortical bone showed that loading increased formation surface (FS/BS), mineral appositional rate (MAR), and bone formation rate (BFR/BS) significantly at the lateral periosteal surface (P < 0.001); however, the effect of ONO-4819 was not significant. At the medial periosteal surface, loading increased the three parameters (P < 0.001) and ONO-4819 increased FS/BS (P < 0.001) and MAR (P < 0.05) significantly. At the endocortical surface, the effects of both loading and ONO-4819 were significant on all three parameters (for loading; FS/BS P < 0.01, MAR P < 0.05, BFR/BS P < 0.03, for ONO-4819 all P < 0.001). It was concluded that ONO-4819 increased cortical bone formation in rats and there was an additive effect on the bone response to external loading by 4-point bending.

Hematologic changes associated with the appearance of eccentrocytes after intragastric administration of garlic extract to dogs

OBJECTIVE

To determine whether dogs given garlic extract developed hemolytic anemia and to establish the hematologic characteristics induced experimentally by intragastric administration of garlic extract.

ANIMALS

8 healthy adult mixed-breed dogs.

PROCEDURE

4 dogs were given 1.25 ml of garlic extract/kg of body weight (5 g of whole garlic/kg) intragastrically once a day for 7 days. The remaining 4 control dogs received water instead of garlic extract. Complete blood counts were performed, and methemoglobin and erythrocyte-reduced glutathione concentrations, percentage of erythrocytes with Heinz bodies, and percentage of eccentrocytes were determined before and for 30 days after administration of the first dose of garlic extract. Ultrastructural analysis of eccentrocytes was performed.

RESULTS

Compared with initial values, erythrocyte count, Hct, and hemoglobin concentration decreased to a minimum value on days 9 to 11 in dogs given garlic extract. Heinz body formation, an increase in erythrocyte-reduced glutathione concentration, and eccentrocytes were also detected in these dogs. However, no dog developed hemolytic anemia.

CONCLUSIONS AND CLINICAL RELEVANCE

The constituents of garlic have the potential to oxidize erythrocyte membranes and hemoglobin, inducing hemolysis associated with the appearance of eccentrocytes in dogs. Thus, foods containing garlic should not be fed to dogs. Eccentrocytosis appears to be a major diagnostic feature of garlic-induced hemolysis in dogs.