The use of α- or β-blockers to ameliorate the chronic stress of captivity in the house sparrow (Passer domesticus).

Clare Parker Fischer,L Michael Romero

doi:10.1093/conphys/cow049

Abstract

When wild animals are brought into captivity for the first time, they frequently develop chronic stress symptoms. Animals can develop glucocorticoid dysregulation or changes in the sympathetic nervous system over the course of the first week in captivity. By blocking the action of epinephrine and norepinephrine using α- or β-blockers, we hoped to reduce the degree of chronic stress symptoms exhibited by newly captured house sparrows. We measured corticosterone, heart rate and heart rate variability in 24 house sparrows (Passer domesticus) over the first week of captivity. The birds were treated with saline, propranolol (a β-blocker) or phentolamine (an α-blocker) for the first 3days of captivity. We also compared newly captured animals with animals that had been held in captivity for 1month. During the first week of captivity, baseline corticosterone increased, but that increase was blocked by propranolol. Heart rate was not different between the treatment groups, but it was higher during the first week than after 1month in captivity. Sympathetic nervous system activity (as measured by heart rate variability) decreased over the first week of captivity, but was not affected by treatment. β-Blockers, but not α-blockers, might help to improve some symptoms of chronic stress in newly captured animals.

Highlights

When wild animals are brought into captivity, they are faced with circumstances unlike any they have experienced before
Propranolol, phentolamine and saline were injected into eight animals that had been living in captivity for >28 days
We found that propranolol-treated birds had significantly higher maximal heart rate at day 7 compared with day 1 (F1,5.3 = 10.49, P = 0.02), but maximal heart rate did not change between day 1 and day 7 in saline- or phentolamine-treated birds

Summary

Introduction

When wild animals are brought into captivity, they are faced with circumstances unlike any they have experienced before. Chronic stress develops in wild animals of many species when they are brought into captivity Terio et al, 2004; Cabezas et al, 2007; Dickens et al, 2009; Adams et al, 2011; Lattin et al, 2012). The effects of captivity on glucocorticoid hormones are relatively well documented in birds (Wingfield et al, 1982; Dickens et al, 2009; Adams et al, 2011; Lattin et al, 2012), less is known about the catecholamine side of the response. When animals overproduce epinephrine (E) and norepinephrine (NE) during the first few days of captivity, this may

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