Further disentangling the motivational processes underlying benzodiazepine hyperphagia.

In addition to their well-known anxiolytic functions, benzodiazepines produce hyperphagia. Previously, we reported that the benzodiazepine, chlordiazepoxide (CDP), increased consumption of both normally-preferred and normally-avoided taste stimuli during long-term (1 h) tests, primarily through changes in licking microstructure patterns associated with hedonic taste evaluation, whereas there was little effect on licking microstructure measures associated with post-ingestive feedback. In this study, we further examined the hedonic and motivational specificity of CDP effects on ingestive behavior. We tested brief access (15 s) licking responses for tastants spanning all taste qualities after treatment with either CDP (5 or 10 mg/kg) or the non-benzodiazepine anxiolytic, buspirone (1.5 or 3 mg/kg). A between-subjects, counterbalanced design compared the CDP or buspirone effects on licking responses for water and a range of weak to strong concentrations of NaCl, Q-HCl, citric acid, MSG, saccharin, and capsaicin under water-restricted (23 h) conditions; and sucrose, saccharin, and MSG under water-replete conditions. In a dose dependent manner, CDP increased licking for taste stimuli that were normally-avoided after saline treatment, with a notable exception observed for the trigeminal stimulus, capsaicin, which was not affected at any concentration or drug dose, suggesting a taste-specific effect of CDP on orosensory processing. Under water-replete conditions, CDP dose-dependently increased licking to normally-accepted concentrations of sucrose, saccharin, and MSG. There was no effect of either drug on licks for water under either water-restricted or water-replete conditions. Buspirone slowed oromotor coordination by increasing brief interlick intervals, but it did not affect licking for any concentrations of the tastants. Overall, these results indicate that benzodiazepines selectively enhance the hedonic acceptance of gustatory orosensory stimuli, independent of general anxiolytic or oromotor coordination effects, or physiological states such as thirst.

Tissue hypoxia during ischemic stroke: adaptive clues from hypoxia-tolerant animal models.

The treatment and prevention of hypoxic/ischemic brain injury in stroke patients remain a severe and global medical issue. Numerous clinical studies have resulted in a failure to develop chemical neuroprotection for acute, ischemic stroke. Over 150 estimated clinical trials of ischemic stroke treatments have been done, and more than 200 drugs and combinations of drugs for ischemic and hemorrhagic strokes have been developed. Billions of dollars have been invested for new scientific breakthroughs with only limited success. The revascularization of occluded cerebral arteries such as anti-clot treatments of thrombolysis has proven effective, but it can only be used in a 3-4.5h time frame after the onset of a stroke, and not for every patient. This review is about novel insights on how to resist tissue hypoxia from unconventional animal models. Ability to resist tissue hypoxia is an extraordinary ability that is not common in many laboratory animals such as rat and mouse models. For example, we can learn from a naked mole-rat, Chrysemys picta, how to actively regulate brain metabolic activity to defend the brain against fluctuating oxygen tension and acute bouts of oxidative stress following the onset of a stroke. Additionally, a euthermic arctic ground squirrel can teach us how the brain of a stroke patient can remain well oxygenated during tissue hypoxia with no evidence of cellular stress. In this review, we discuss how these animals provide us with a system to gain insight into the possible mechanisms of tissue hypoxia/ischemia. This issue is of clinical significance to stroke patients. We describe specific physiological and molecular adaptations employed by different animals' models of hypoxia tolerance in aquatic and terrestrial environments. We highlight how these adaptations might provide potential clues on strategies to adapt for the clinical management of tissue hypoxia during conditions such as stroke where oxygen demand fails to match the supply.