Behavioural Endocrinology Behavioural Endocrinology اا:: Introduction and Case StudyIntroduction and Case Study

Text Chapter 8Text Chapter 8

ContentsContents

• Basic review of the endocrine systemBasic review of the endocrine system

• Hormone types, modes of action and categories Hormone types, modes of action and categories of influenceof influence

• Case study: Growth hormone and salmonid fishesCase study: Growth hormone and salmonid fishes

• Darek’s research – An ecological assessmentDarek’s research – An ecological assessment

DefinitionsDefinitionsBehavioural EndocrinologyBehavioural Endocrinology: The study of hormonal influence on : The study of hormonal influence on

behaviour and the behavioural influence on hormone behaviour and the behavioural influence on hormone expressionexpression

HormoneHormone: Organic chemical substance produced by an : Organic chemical substance produced by an endocrine gland, endocrine gland, exocrine gland or neurosecretory cell exocrine gland or neurosecretory cell (neurohormone) that may alter the physiology and/or (neurohormone) that may alter the physiology and/or behaviour of an organismbehaviour of an organism

Neuroseretory Neuroseretory

CellCell

Target TissueTarget Tissue

Endocrine/Exocrine Endocrine/Exocrine

GlandGland

Physiological/BehaviouralPhysiological/Behavioural

ChangeChange

CNSCNS

Endocrine System FeaturesEndocrine System Features

• Modified nerve cells Modified nerve cells

• Secrete neurohormones into Secrete neurohormones into bloodstreambloodstream

• Direct and indirect actionsDirect and indirect actionsExocrine GlandsExocrine Glands::

• release hormones via ducts or tubesrelease hormones via ducts or tubes

• Affect adjacent organs or external Affect adjacent organs or external environment environment

Neurosecretory CellsNeurosecretory Cells::

Eckert 2000 Nelson 1995

EndocrineEndocrine GlandsGlands::

• highly vascularized, ductlesshighly vascularized, ductless

• Secrete hormones into bloodstreamSecrete hormones into bloodstream

• Attach to specific binding sites called Attach to specific binding sites called hormone receptorshormone receptors

• Affect any cell with receptorsAffect any cell with receptors

Endocrine System FeaturesEndocrine System Features

Nelson 1995

Hormone TypesHormone Types

1) 1) AminesAmines: :

• small, amino acid-derivedsmall, amino acid-derived

• include catecholamines and thyroid hormonesinclude catecholamines and thyroid hormones

2) 2) ProstaglandinsProstaglandins::

• synthesized in membranessynthesized in membranes

• cyclic unsaturated hydroxy fatty acidscyclic unsaturated hydroxy fatty acids

• include thromboxaneinclude thromboxane

3) Steroid Hormones:3) Steroid Hormones:• cyclic hydrocarbon derivatives cyclic hydrocarbon derivatives synthesized from steroid synthesized from steroid cholesterolscholesterols

• include testosterone and include testosterone and estrogenestrogen

Hormone TypesHormone Types

4) Peptide/Protein Hormones:4) Peptide/Protein Hormones:

• largest, most complexlargest, most complex

• includes insulin, growth hormoneincludes insulin, growth hormone

ExampleExample Pathways…Pathways…

Feedback LoopsFeedback Loops

• Feedback loops help regulate Feedback loops help regulate the secretion of many hormonesthe secretion of many hormones

1) Negative Feedback - Control 1) Negative Feedback - Control of secretion of adrenocortical of secretion of adrenocortical steroidssteroids

2) Positive Feedback - Estrogen 2) Positive Feedback - Estrogen and LH during LH surgeand LH during LH surge

Synergism and AntagonismSynergism and AntagonismSynergy and permissive effectsSynergy and permissive effects : :

•  Epinephrine and nor-epinepherine both increase the Epinephrine and nor-epinepherine both increase the heart rate singly, but together effect is greater heart rate singly, but together effect is greater

• One hormone can also increase the responsiveness One hormone can also increase the responsiveness of a tissue to a second hormone (Exposure of the of a tissue to a second hormone (Exposure of the uterus to estrogen increases its response to uterus to estrogen increases its response to progesterone)progesterone)

• Small amounts of one hormone may assist in the Small amounts of one hormone may assist in the maturation of receptors for a second hormone, known maturation of receptors for a second hormone, known as as up regulationup regulation       

Antagonistic EffectsAntagonistic Effects : :

• Insulin and glucagon, have Insulin and glucagon, have antagonistic effects on blood glucose antagonistic effects on blood glucose levels and on the cellular uptake and levels and on the cellular uptake and use of glucoseuse of glucose

• Prolonged exposure to polypeptide Prolonged exposure to polypeptide hormones desensitize target cells and hormones desensitize target cells and promote receptor promote receptor down regulationdown regulation

(i.e. release of FSH and LH in the (i.e. release of FSH and LH in the ovulatory cycle)ovulatory cycle)

Synergism and AntagonismSynergism and Antagonism

Categories of InfluenceCategories of Influence

• Organizational effects versus Organizational effects versus activational effects activational effects

Organizational EffectsOrganizational Effects: result in long-term : result in long-term changes in body tissues manifested during changes in body tissues manifested during critical periods of developmentcritical periods of development

(i.e. sex determination)(i.e. sex determination)

Activational EffectsActivational Effects: relative expression of a : relative expression of a hormone correlates with the behavioural hormone correlates with the behavioural responseresponse

(i.e. testosterone level and aggression) (i.e. testosterone level and aggression)

Case Study: GH and Case Study: GH and SalmonidsSalmonids

Growth HormoneGrowth Hormone: :

• Polypeptide hormone Polypeptide hormone

• Involved in somatic growth, Involved in somatic growth, metabolism, energy utilization and metabolism, energy utilization and osmoregulationosmoregulation

What is a transgenic fish?What is a transgenic fish?

• TransgenicTransgenic: : Any organism containing stable foreign DNA within its genome

• Genetically Genetically heritableheritable

Modified from Du et al. 1992

A-F D-R

331 bp

2653 2654

207 bp

Ocean Pout AFP 5’ promoter region

Ocean Pout AFP 3’ region

Chinook salmon GH cDNA

1 2193 2897 4061

M N

534 bp

Oppro-F 841 R

826 bp

815 F 1559 R

745 bp

1963 F B

972 bp

opAFPGHc2

Transgenic DebateTransgenic Debate

ProsPros • Increased productivityIncreased productivity

( profits and/or ( profits and/or market value)market value)

• Increased food supplyIncreased food supply

ConsCons• Ecological implicationsEcological implications

• Human health Human health implicationsimplications

Ecological ConcernsEcological Concerns

Gross 1998

Ecologically Risky Ecologically Risky Physiology?Physiology?

• growth ratesgrowth rates

• rate of energy reserve rate of energy reserve

loss loss (Cook et al. (Cook et al.

2000)2000)

• Intrinsic metabolism? Intrinsic metabolism? AQUA Bounty Inc.

External stimuli

Animal(G+E+I)+(A+P)

Internal stimuli

Behaviour(s)

Consequences

Conditioned Future Response

Negative feedback

Positive Feedback

(Proximate & Ultimate)

Modified from Lehner 1996

• GH transgenesis directly alters the genetic, GH transgenesis directly alters the genetic, anatomonic, and physiological components of anatomonic, and physiological components of internal stimuli internal stimuli

• Behavioural consequences may impact Behavioural consequences may impact fitnessfitness

Peripheral GH InjectionPeripheral GH Injection

Behavioural Behavioural ResponsesResponses:: spontaneous activity spontaneous activity

appetiteappetite

aggressionaggression

antipredator antipredator behaviourbehaviour

Table 1. Highlighted behavioural differences between growth hormone transgenic and non-transgenic Coho (Oncorhynchus kisutch) and Atlantic (Salmo salar) salmon juveniles.

SpeciesGene

Construct

Behavioural Observations Reference

Coho salmon OnMTGH1Greater foraging efficiency and

learning rate; increased swallowing time

Sundstroem et al. 2004a

Coho salmon OnMTGH1Low food abundance caused

greater mortality in transgenic-containing groups

Devlin et al. 2004

Coho salmon OnMTGH1Increased predation mortality;

decreased growth rate at low feeding levels

Sundstroem et al. 2004b

Coho salmon OnMTGH1Decreased antipredator

behaviourSundstroem et al.

2003

Coho salmon OnMTGH1Out compete in pair-wise food

contestsDevlin et al. 1999

Atlantic salmon

opAFPGHc

Decreased antipredator behaviour; increased activity

Abrahams and Sutterlin 1999

Nelson 1995

• Hormones can act on all the behavioural Hormones can act on all the behavioural components of an organismcomponents of an organism

• Change the probability that certain behaviours Change the probability that certain behaviours will be emitted indirectly by acting on one or will be emitted indirectly by acting on one or more of these three systems more of these three systems

Bjornsson et al Bjornsson et al 20042004

CNS and HormonesCNS and Hormones

• Hormones may act on the CNS directly or Hormones may act on the CNS directly or indirectlyindirectly

• GH receptors exist in salmonid brain, but GH receptors exist in salmonid brain, but direct mechanism unknowndirect mechanism unknown• Monoamine neurotransmitters influence Monoamine neurotransmitters influence agonistic behaviour and stress reactions in agonistic behaviour and stress reactions in teleoststeleosts

Dopaminergic systemDopaminergic system: positively correlated : positively correlated to aggression and swimming activityto aggression and swimming activity

Serotonergic systemSerotonergic system: negatively correlated : negatively correlated with aggression and swimming activity with aggression and swimming activity

Direct CNS

Influence

Greater Metabolic

Requirement

Increased Appetite

Increased Spontaneous Activity

Greater Feeding Motivation

Reduced Antipredator Behaviour

Increased Aggression

Jonsson et al. 2003Jonsson et al. 2003

Dominance

Bottlenecks of Bottlenecks of survival:survival: • Reproductive successReproductive success

• Early freshwater phase Early freshwater phase

(survival from egg to (survival from egg to smolt)smolt)

Redd Emergence Redd Emergence

• Establish foraging territories Establish foraging territories (McNichol and (McNichol and Noakes 1981)Noakes 1981)

• Unsuccessful fry displaced downstream Unsuccessful fry displaced downstream (Bujold et al(Bujold et al.. 2004) 2004)

• Physiological costs and predation risks Physiological costs and predation risks may be incurredmay be incurred

N. Giles N. Giles

Fry CompetitionFry Competition

• Body sizeBody size

• Prior Prior experienceexperience

• AggressionAggression

• Prior Prior residenceresidence

Factors influencing Factors influencing territory territory recruitment/retention:recruitment/retention:

(Deverill et al. 1999)

N. Giles

Prior ResidencePrior Residence

• Competitive advantage held by existing occupants over Competitive advantage held by existing occupants over a contested space a contested space

• Prior residence > aggression Prior residence > aggression (O’Connor et al. 2000)(O’Connor et al. 2000)

• Prior residence > body size Prior residence > body size (Metcalfe et al. 2003)(Metcalfe et al. 2003)

Will early territorial relationships involving transgenics Will early territorial relationships involving transgenics differ?differ?

• Aggression vs. prior Aggression vs. prior residencyresidency

How will increased aggression in GHT parr influence How will increased aggression in GHT parr influence territory size and competitive interactions in a territory size and competitive interactions in a

naturalized stream environment?naturalized stream environment?

• Quantify territory size and Quantify territory size and aggressive interactionsaggressive interactions

Behavioural Asymmetries?Behavioural Asymmetries?

Physiological Asymmetries?Physiological Asymmetries?

Deitch et al.Deitch et al. (unpublished):(unpublished): Intrinsic Intrinsic in post-smolt transgenic Atlantic in post-smolt transgenic Atlantic salmonsalmon

• Alevin respiratory metabolismAlevin respiratory metabolism

• Endogenous phase characteristicsEndogenous phase characteristics