Behavioural Endocrinology ا: Introduction and Case Study Text Chapter 8

Contents Basic review of the endocrine system Basic review of the endocrine system Hormone types, modes of action and categories of influence Hormone types, modes of action and categories of influence Case study: Growth hormone and salmonid fishes Case study: Growth hormone and salmonid fishes Darek’s research – An ecological assessment Darek’s research – An ecological assessment

Definitions Behavioural Endocrinology: The study of hormonal influence on behaviour and the behavioural influence on hormone expression Hormone: Organic chemical substance produced by an endocrine gland, exocrine gland or neurosecretory cell (neurohormone) that may alter the physiology and/or behaviour of an organism NeuroseretoryCell Target Tissue Endocrine/ExocrineGland Physiological/BehaviouralChange CNS

Endocrine System Features Modified nerve cells Modified nerve cells Secrete neurohormones into bloodstream Secrete neurohormones into bloodstream Direct and indirect actions Direct and indirect actions Exocrine Glands: release hormones via ducts or tubes release hormones via ducts or tubes Affect adjacent organs or external environment Affect adjacent organs or external environment Neurosecretory Cells: Eckert 2000Nelson 1995

Endocrine Glands: highly vascularized, ductless highly vascularized, ductless Secrete hormones into bloodstream Attach to specific binding sites called hormone receptors Attach to specific binding sites called hormone receptors Affect any cell with receptors Affect any cell with receptors Endocrine System Features Nelson 1995

Hormone Types 1) Amines: small, amino acid-derived small, amino acid-derived include catecholamines and thyroid hormones include catecholamines and thyroid hormones 2) Prostaglandins: synthesized in membranes synthesized in membranes cyclic unsaturated hydroxy fatty acids cyclic unsaturated hydroxy fatty acids include thromboxane include thromboxane

3) Steroid Hormones: cyclic hydrocarbon derivatives synthesized from steroid cholesterols cyclic hydrocarbon derivatives synthesized from steroid cholesterols include testosterone and estrogen include testosterone and estrogen Hormone Types 4) Peptide/Protein Hormones: largest, most complex largest, most complex includes insulin, growth hormone includes insulin, growth hormone

ExamplePathways… Example Pathways…

Feedback Loops Feedback loops help regulate the secretion of many hormonesFeedback loops help regulate the secretion of many hormones 1) Negative Feedback - Control of secretion of adrenocortical steroids 2) Positive Feedback - Estrogen and LH during LH surge 2) Positive Feedback - Estrogen and LH during LH surge

Synergism and Antagonism Synergy and permissive effects : Epinephrine and nor-epinepherine both increase the heart rate singly, but together effect is greater Epinephrine and nor-epinepherine both increase the heart rate singly, but together effect is greater One hormone can also increase the responsiveness of a tissue to a second hormone (Exposure of the uterus to estrogen increases its response to progesterone) One hormone can also increase the responsiveness of a tissue to a second hormone (Exposure of the uterus to estrogen increases its response to progesterone) Small amounts of one hormone may assist in the maturation of receptors for a second hormone, known as up regulation Small amounts of one hormone may assist in the maturation of receptors for a second hormone, known as up regulation

Antagonistic Effects : Insulin and glucagon, have antagonistic effects on blood glucose levels and on the cellular uptake and use of glucose Insulin and glucagon, have antagonistic effects on blood glucose levels and on the cellular uptake and use of glucose Prolonged exposure to polypeptide hormones desensitize target cells and promote receptor down regulation Prolonged exposure to polypeptide hormones desensitize target cells and promote receptor down regulation (i.e. release of FSH and LH in the ovulatory cycle) Synergism and Antagonism

Categories of Influence Organizational effects versus activational effects Organizational effects versus activational effects Organizational Effects: result in long-term changes in body tissues manifested during critical periods of development (i.e. sex determination) Activational Effects: relative expression of a hormone correlates with the behavioural response (i.e. testosterone level and aggression)

Case Study: GH and Salmonids Growth Hormone: Polypeptide hormone Polypeptide hormone Involved in somatic growth, metabolism, energy utilization and osmoregulation Involved in somatic growth, metabolism, energy utilization and osmoregulation

What is a transgenic fish? Transgenic: Transgenic: Any organism containing stable foreign DNA within its genome Genetically heritable Genetically heritable Modified from Du et al A-FD-R 331 bp bp Ocean Pout AFP 5’ promoter region Ocean Pout AFP 3’ region Chinook salmon GH cDNA MN 534 bp Oppro-F841 R 826 bp 815 F1559 R 745 bp 1963 FB 972 bp opAFPGHc2

Transgenic Debate  Pros Increased productivity Increased productivity ( profits and/or market value) Increased food supply Increased food supply  Cons Ecological implications Ecological implications Human health implications Human health implications

Ecological Concerns Gross 1998

Ecologically Risky Physiology? growth rates growth rates rate of energy reserve loss (Cook et al. 2000) rate of energy reserve loss (Cook et al. 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, anatomonic, and physiological components of internal stimuli Behavioural consequences may impact fitness Behavioural consequences may impact fitness

Peripheral GH Injection Behavioural Responses: spontaneous activity spontaneous activity appetite appetite aggression aggression antipredator behaviour antipredator behaviour

Table 1. Highlighted behavioural differences between growth hormone transgenic and non-transgenic Coho (Oncorhynchus kisutch) and Atlantic (Salmo salar) salmon juveniles. Species Gene Construct Behavioural ObservationsReference Coho salmonOnMTGH1 Greater foraging efficiency and learning rate; increased swallowing time Sundstroem et al. 2004a Coho salmonOnMTGH1 Low food abundance caused greater mortality in transgenic-containing groups Devlin et al Coho salmonOnMTGH1 Increased predation mortality; decreased growth rate at low feeding levels Sundstroem et al. 2004b Coho salmonOnMTGH1Decreased antipredator behaviourSundstroem et al Coho salmonOnMTGH1 Out compete in pair-wise food contests Devlin et al Atlantic salmonopAFPGHc Decreased antipredator behaviour; increased activity Abrahams and Sutterlin 1999

Nelson 1995 Hormones can act on all the behavioural components of an organism Hormones can act on all the behavioural components of an organism Change the probability that certain behaviours will be emitted indirectly by acting on one or more of these three systems Change the probability that certain behaviours will be emitted indirectly by acting on one or more of these three systems

Bjornsson et al 2004

CNS and Hormones Hormones may act on the CNS directly or indirectly Hormones may act on the CNS directly or indirectly GH receptors exist in salmonid brain, but direct mechanism unknown GH receptors exist in salmonid brain, but direct mechanism unknown Monoamine neurotransmitters influence agonistic behaviour and stress reactions in teleosts Monoamine neurotransmitters influence agonistic behaviour and stress reactions in teleosts Dopaminergic system: positively correlated to aggression and swimming activity Dopaminergic system: positively correlated to aggression and swimming activity Serotonergic system: negatively correlated with aggression and swimming activity Serotonergic system: negatively correlated 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 Dominance

Bottlenecks of survival: Reproductive success Early freshwater phase Early freshwater phase (survival from egg to smolt) (survival from egg to smolt)

Redd Emergence Establish foraging territories (McNichol and Noakes 1981) Unsuccessful fry displaced downstream (Bujold et al. 2004) Unsuccessful fry displaced downstream (Bujold et al. 2004) Physiological costs and predation risks may be incurred Physiological costs and predation risks may be incurred N. Giles

Fry Competition Body size Body size Prior experience Prior experience Aggression Aggression Prior residence Prior residence Factors influencing territory recruitment/retention: (Deverill et al. 1999) N. Giles

Prior Residence Competitive advantage held by existing occupants over a contested space Competitive advantage held by existing occupants over a contested space Prior residence > aggression (O’Connor et al. 2000) Prior residence > aggression (O’Connor et al. 2000) Prior residence > body size (Metcalfe et al. 2003) Prior residence > body size (Metcalfe et al. 2003)

Will early territorial relationships involving transgenics differ? Aggression vs. prior residency Aggression vs. prior residency How will increased aggression in GHT parr influence territory size and competitive interactions in a naturalized stream environment? Quantify territory size and aggressive interactions Quantify territory size and aggressive interactions Behavioural Asymmetries?

Physiological Asymmetries? Deitch et al. (unpublished): Intrinsic in post-smolt transgenic Atlantic salmon Alevin respiratory metabolism Alevin respiratory metabolism Endogenous phase characteristics Endogenous phase characteristics