A critical period for functional vestibular development in zebrafish.

We have determined a critical period for vestibular development in zebrafish by using a bioreactor designed by NASA to simulate microgravity for cells in culture. A critical period is defined as the briefest period of time during development when stimulus deprivation results in long lasting or permanent sensory deficits. Zebrafish eggs were collected within 3 hours of being laid and fertilized. In experiment 1, eggs were placed in the bioreactor at 3, 24, 30, 36, 48, or 72 hours postfertilization (hPF) and maintained in the bioreactor until 96 hPF. In experiment 2, eggs were placed in the bioreactor immediately after they were collected and maintained in the bioreactor until 24, 36, 48, 60, 66, 72, or 96 hPF. Beginning at 96 hPF, all larvae had their vestibulo-ocular reflexes (VOR) evaluated once each day for 5 days. Only larvae that hatched from eggs that were placed in the bioreactor before 30 hPF in experiment 1 or removed from the bioreactor later than 66 hPF in experiment 2 had VOR deficits that persisted for at least 5 days. These data suggest a critical period for vestibular development in the zebrafish that begins before 30 hPF and ends after 66 hPF. To confirm this, zebrafish eggs were placed in the bioreactor at 24 hPF and removed at 72 hPF. VORs were evaluated in these larvae once each day for 5 days beginning at 96 hPF. These larvae had VOR deficits that persisted for at least 5 days. In addition, larvae that had been maintained in the bioreactor from 24 to 66 hPF or from 30 to 72 hPF, had only temporary VOR deficits. In a final experiment, zebrafish eggs were placed in the bioreactor at 3 hPF and removed at 96 hPF but the bioreactor was turned off from 24 hPF to 72 hPF. These larvae had normal VORs when they were removed from the bioreactor at 96 hPF. Taken as a whole, these data support the idea that there is a critical period for functional maturation of the zebrafish vestibular system. The developmental period identified includes the timeframe during which the vestibular primary afferent neurons are born, innervate their central and peripheral targets, and remodel their central projections.     

Characterization and opioid modulation of inflammatory temporomandibular joint pain in the rat.

PURPOSE: Experimental inflammation of the rat temporomandibular joint (TMJ) is commonly used to study trigeminal nociceptive processing. This study describes spontaneous pain-related behaviors following TMJ inflammation in the rat. The ability of preemptive systemic morphine to attenuate behaviors as well as immediate-early gene expression in the trigeminal nucleus is described. MATERIALS AND METHODS: Adult male Sprague-Dawley rats received an intra-articular injection of mustard oil (0% to 20%, 50 microL) and were observed for behavioral changes. Morphine sulfate (0 to 10 mg/kg SC) was given 30 minutes before mustard oil; this was reversed in one group with naltrexone hydrochloride (5 mg/kg SC). Two hours after injection rats were killed and perfused. Immunohistochemistry for the protein product of the immediate-early gene c-fos was performed, and brain stem sections including the trigeminal subnucleus caudalis were examined for positive nuclei. RESULTS: Mustard oil inflammation of the rat TMJ induces dose-dependent, morphine-sensitive behaviors. Behaviors observed included excessive grooming of the region, a chewing-like behavior, and head shaking. Fos expression in the trigeminal subnucleus caudalis parallels changes in behaviors. Morphine dose dependently attenuates the number of behaviors, as well as Fos expression; this effect is reversed by the micro-opioid receptor antagonist naltrexone. CONCLUSIONS: Mustard oil inflammation of the rat TMJ causes reliable behavioral changes, which may be quantified and, together with Fos expression, used to assess various experimental TMJ treatment modalities.     

Reduced 293T cell susceptibility to acrolein due to aldose reductase-like-1 protein expression.

Acrolein is a highly reactive alpha,beta-unsaturated aldehyde produced endogenously during lipid peroxidation and naturally distributed pervasively in living environments, posing serious threats to human health if not properly metabolized. In this study, we report aldose reductase-like-1 (ARL-1) as a novel enzyme that catalyzes the reduction of acrolein and protects cells from their toxicity. Using purified ARL-1 protein, we determined its enzymatic activity in response to acrolein and defined its steady-state kinetics with K(m) and V(max) at 0.110 +/- 0.012 mM and 3122.0 +/- 64.7 nmol/mg protein/min, respectively. By introducing a functional Enhanced Green Fluorescent Protein (EGFP)/ARL-1 fusion protein into 293T cells, we demonstrated that plating efficiency in liquid culture and focus formation in soft agar increased by more than 60% (p < 0.05), compared to the vector control cells. More significantly, at a low dose of 5 microM acrolein, EGFP/ARL-1 expression enhanced both plating efficiency and focus formation by more than threefold, and the foci (in soft agar) of 293T cells expressing EGFP/ARL-1 were significantly larger than those of the vector control cells. At high concentrations of acrolein (25 and 50 microM), EGFP/ARL-1 protein prevented oncotic death of 293T cells induced by acrolein. In summary, our data demonstrated for the first time that the ARL-1 protein protects 293T cells from acrolein toxicity. Due to the high toxicity and wide distribution of acrolein, this finding is important to the understanding of its detoxification mechanisms.     

Is Functional Dyspepsia of Particular Concern in Women? A Review of Gender Differences in Epidemiology, Pathophysiologic Mechanisms, Clinical Presentation, and Management

Dyspepsia is a remarkably common symptom in the general population. Although multiple definitions have been used to describe the symptom, the most common explanation is that of chronic or recurrent pain or discomfort (a subjective negative feeling that may be associated with early satiety, fullness, bloating, or nausea) centered in the upper abdomen. When a thorough evaluation of a dyspeptic patient fails to identify a cause for her symptoms, the label of nonulcer or functional dyspepsia is applied. Functional dyspepsia is a heterogeneous disorder characterized by relapsing and remitting symptoms. Treatment strategies should focus on alleviating the most bothersome symptom and can be based on the proposed underlying pathophysiology. The effect of gender on mechanisms of disease, symptom presentation, and treatment response is an area of increasing interest and study. As with other functional gastrointestinal disorders, there appear to be some gender-specific features of functional dyspepsia. Specifically, gender-related differences have been observed in some studies of both the prevalence of individual dyspepsia symptoms, and in gastric emptying and proximal gastric motor function. There also appear to be gender differences in the psychosocial realm, with dyspeptic women experiencing a lesser sense of well-being than dyspeptic men, as well as an association of an abuse history with functional dyspepsia. This review will highlight specific gender differences related to the symptom presentation, pathophysiology, and approach to treatment of functional dyspepsia, while noting where differences have not been found and where further investigation is warranted.