A transient reduction in circulating corticosterone reduces object neophobia in male house sparrows.

Aversive reactions to novelty (or "neophobia") have been described in a wide variety of different animal species and can affect an individual's ability to exploit new resources and avoid potential dangers. However, despite its ecological importance, the proximate causes of neophobia are poorly understood. In this study, we tested the role of glucocorticoid hormones in neophobia in wild-caught house sparrows (Passer domesticus, n = 11 males) by giving an injection of the drug mitotane that reduced endogenous corticosterone for several days or a vehicle control, and then examined the latency to feed when the food dish was presented with or without a novel object in, on, or near the dish. Each sparrow was exposed to multiple novel object and control trials and received both vehicle control and mitotane treatments, with a week between treatments to allow the drug to wash out. As found previously, all novel objects significantly increased sparrows' latency to feed compared to no object present. Reducing corticosterone using mitotane significantly reduced the latency to feed in the presence of novel objects. In control trials without objects, mitotane had no significant effects on feeding time. Although we have shown that corticosterone affects neophobia, further studies using specific receptor agonists and antagonists will help clarify the neurobiological mechanisms involved and determine whether baseline or stress-induced corticosterone is driving this effect. These results suggest that increased glucocorticoids (e.g., due to human-induced stressors) could increase neophobia, affecting the ability of individuals to exploit novel resources, and, ultimately, to persist in human-altered environments.

[Diagnostic importance of visken -- an adrenergic beta receptor blocking agent]. / Diagnosticheskoe znachenie viskena - blokatora beta- adrenergicheskikh retseptorov?

Among the newest beta-blocking agents visken is the one that either produces no or very little adverse inotropic effect. In some groups of patients with organic and neurotic cardiac disorders, screened as a result of a careful clinical examination, changes that occurred on the ECG with 12 leads following an intake of a single visken tablet (5 mg) were studied. Ingestion of visken was not seen to bring any improvement in the ECG findings in 88 per cent of 50 patients with organic disorders, most of whom had sclerosis of the coronary arteries and hypertensive disease attended by a high diastolic pressure. A thorough clinical examination of 70 patients presenting neurotic conditions helped to rule out any organic cardiac lesions, and in them the diastolic pressure did not exceed 95 mm Hg. The visken test showed that in 91 per cent of these cases the ECG returned back to normal and only in 1.5 per cent of them no changes could be observed. In both of the above groups the effect of visken was statistically significant (p less than 0.001). Repolarization derangements in the I and II leads among patients with organic lesions was observed 4 times as often as in the II and III leads. Among neurotic patients changes recorded in the II and III leads were twice as frequent as in the I and II leads.