Coping with Stress: Does having a single parent affect offspring of typically biparental zebra finches (Taeniopygia guttata)

Leslie S. Phillmore, Jordan Fisk, Sean D. Aitken, Tareq Yousef, Tara S. PerrotDepartments of Psychology and Neuroscience1 and Biology2

Introduction

Dalhousie University, Halifax, NS Canada

Conclusions

Future Directions

References

Acknowledgments

1. McLeod J, Sinal CJ, Perrot-Sinal TS. (2007) Evidence for non-genomic transmission of ecological information via maternal behavior in female rats. Genes Brain Behav 6:19-29. 2. Royle NJ, Hartley IR, Parker GA. (2006) Consequences of biparental care for begging and growth in zebra finches, Taeniopygia guttata. Anim Behav 72:123-130.3. Banerjee, SB, Arterbery AS, Fergus DJ, Adkins-Regan E. (2012) Deprivation of maternal care has long-lasting consequences for the hypothalamic-pituitary-adrenal axis of zebra finches. Proc R Soc B 279:759-766.4. Schmidt KL, Chin EH, Shah AH, Soma KK. (2009) Cortisol and corticosterone in immune organs and brain of European starlings: developmental changes, effects of restraint stress, comparison with zebra finches. Am J Physiol Reful Interg Comp Physiol; 297: R42-R51.

Results

Methods

Offspring Physiology

Offspring Behaviour Offspring Behaviour:• Offspring of single mothers were fed

fewer times but also begged less

than offspring in biparental and

single father nests.

Offspring Physiology:• All offspring, regardless of rearing

condition, gained weight from PHD 8

to PHD 13, despite single-mothers

feeding at a lower rate.• Single-mothers may be feeding more

food in one feeding bout OR offspring

of single mothers may move less to

conserve energy – e.g. less begging.

• Female offspring had higher baseline

CORT than males.

• GCR Results:• Preliminary data was too small to

reveal significant statistical results.

• However, it appears females reared

by a single mother have increased

GCRs in Hp, indicating they may

have more resilience to cope with

higher levels of circulating CORT.

• Analyse remaining sections for

GCR in Hp and other areas.

• Analyse relationships among

GCR levels, CORT levels, and

parental and offspring behaviours.

Behaviors Recorded

Weights

Feeds received

Begging (time, intensity)

Glucocorticoid Receptors

Video Analyses

• Modeling effects of developmental stress primarily uses rodents where only maternal care is provided1.

• Zebra finches provide bi-parental care to offspring, allowing us to test effects of either mother or father removal on parent and offspring behaviours and stress levels2.

• Previous work in finches showed removal of mother had no effect on GCR mRNA in the hippocampus3.

• In this study we removed either the father or the mother of a brood and examined:

• Offspring behaviour in first 2 weeks post hatch• Baseline and acute stress response levels of corticosterone4

• Number of glucocorticoid receptors (GCRs) in hippocampus

• Analyzed 2h of video

• Sampled behaviour for 1 min every 5 min

• Total of 24 one-min samples

Jill Squires collected the behavioural data. Ashley Lockyer, Dominique Shephard, and Jaya Wadhawan helped with bird care, video recording, and project management.

539.11CC11

*

PHD30 PHD90 PHD120 Stress0

5000

10000

15000

20000

25000

Biparental Male (4)

Biparental Female (2)

Single Male (9)

Single Female (4)

Bleed DayP

lasm

a C

ort

ico

ster

on

e (p

g/m

l)

*

Offspring reared in single mother nests had higher circulating CORT than offspring reared in single father nests, but did not differ from biparental offspring. Females had higher CORT than males. After exposure to acute stress, CORT levels rose significantly over baseline.

Offspring weighed more on PHD 13 than PHD 8 (F (F(1,34)= 177.10, p <0.001). On PHD 8, offspring in biparental nests weighed significantly less than offspring in single father nests (F(2,41)= 5.72, p =0.01).

Offspring begged less on PHD 13 than on PHD 8 (F(1,12)= 5.45, p=0.04), and offspring in single mother nests begged less than offspring in both biparental and single father nests on both PHD 8 and 13 (F(2,12)= 10.90, p=0.002).

PHD 8 PHD 130

0.02

0.04

0.06

0.08

0.1

0.12

Prop

ortio

n of

Tim

e Be

ggin

g

* * * *

*

PHD 8 PHD 130

0.1

0.2

0.3

0.4

0.5

0.6 Biparental

Single Mother

Single Father

Fe

ed

s p

er

Min

ute

*

PHD 8 PHD 130

2

4

6

8

10

12

We

igh

t (g

)

*

*

On PHD 13, offspring in single mother nests received fewer feeds than offspring in biparental nests (F(2,14)= 5.25, p= 0.02).

Error bars represent standard errors of the means.

Pairs of finches allowed to breed

Biparental Father or mother removed 4-5d post hatch

Video tape parental/offspring behaviour

Allow birds to mature

Co

llect

blo

od

fro

m o

ffsp

ring

th

rou

gh

ou

t de

velo

pm

en

t

Expose to acute stressor (restraint) and collect blood

Baseline blood of offspring was collected within five minutes of entering the room at PHD 30, 90, 120. Acute stress was induced by holding the bird in a cloth bag for 30 min before blood collection4. Plasma cort levels were quantified using a standard ELISA kit (ADI-901-097, Enzo Life Sciences). Immunohistochemistry for GCR protein (PA1510A Life Technologies at 1:1000 followed standard steps and was visualized with DAB.

Process blood for baseline and acute

CORT levels

Section brains and process for GCR

protein (IHC)

Biparental Single Mother Single Father0

10

20

30

40

50

60

70

80

90Left

Right

Group

Nu

mb

er o

f G

CR

+ C

ells

Biparental Single Mother Single Father0

10

20

30

40

50

60

70

Group

Nu

mb

er o

f G

CR

+ C

ells

Biparental Single Mother Single Father0

10

20

30

40

50

60

70

80

90Male

Female

Group

Nu

mb

er o

f G

CR

+ C

ells

Males – separated by hemisphere Females – separated by hemisphere

Averaged across hemispheres

A: Coronal section of left hemisphere showing the ROI in hippocampus (Hp), taken at 4x.B: Hp at 20x used for counting GCR+ cells.

A

B

We counted the number of cells labeled with GCR (GCR+) in hippocampus; we used two birds of each sex in each rearing group. We analysed the data using non parametric tests.• There was no difference in number of GCR+

cells between left and right hippocampus (Wilcoxon p=0.14).

• Males and females did not differ in number of GCR+ cells in hippocampus (K-S test p=0.44).

• There were no differences across rearing conditions in number of GCR+ cells.