Neuroendocrine mechanism behaviour in Domestic Animals . some common behaviours are explained in view of their neural and endocrine controls

1. Submitted to
Dr Z A Pampori
Submitted by
Nadia Mushtaq
Ilyas Zargar

2.  Neuroendocrinology : Study of communication
between CNS & Endocrine glands
 Behaviour : Action performed in response to a
stimulus
 Ethology : Study of animal behaviour
 Neuroethology : It is the evolutionary and
comparative approach to the study of animal
behaviour and its underlying mechanistic control
by the nervous system

3.  Behaviour is mainly driven by internal and external
stimuli , with different stimulus elicting different
behaviours .Three main funtional components are
involved :
 Sensory system
 CNS
 Effector system

4. Hypothalamic –pituitary axis

5. Neuroendocrine mechanism of
feeding behaviour
 The CNS undertakes the homeostatic role of sensing
nutrient intake and body reserves integrating the
information and regulating energy intake and energy
expenditure
 Information regarding the metabolic state can be
transmitted to the appetite control centres of the brain
by array of signals such as stimulation of the vagus
nerve or metabolic “feedback” factors derived from the
pituitary gland ,adipose tissue, stomach / abomasum,
intestine, pancreas and/or muscle.

6.  These signals act directly on the neurons located in the
arcuate nucleus of the mediobasal hypothalamus ,a key
integration & hunger (orexigenic)and
satiety(anorexigenic) control centre of the Brain
 Stellar proposed that the ventromedial region of the
hypothalamus was the anorexigenic centre (inhibiting
VFI)and the lateral hypothalamus was the orexigenic
(feeding stimulation)centre
 Anorexigenic signals directly influence VFI responses
that are generated in the limbic system and orexigenic
signals are regulated by neurohormones ,espicially
serotonin in the lateral hypothalamus

7. Arcuate nucleus of Hypothalamus
• VFI regulation site – hypothalamic arcuate nucleus
(ARC)
• ARC contains two distinct neuronal populations that
express leptin and insulin receptors
• One expresses POMC –precursor peptide – processed
into hormones –including anorexigenic hormone
(alpha melanocyte stimulating hormone)
• leptin promotes POMC containing neurons resulting
in the release of alpha MSH . Leptin also interacts
with 2nd ARC population to inhibit the release of
orexigenic NPY and AgPR peptides

8. • Neuropeptide Y (NPY) : one of the most potent
stimulation of feed intake in animals (36AA)found
throughout PNS but also produced in brain (tatemoto et al)
• The end result is that at times of energy excess and/or
increased leptin levels directly impede the activation of the
orexigenic ARC pathways , and stimulate the anorexigenic
associated ARC pathways.
 Gene expression of POMC in the ARC is decreased during
lactation in sheep , facilitating the lactation associated
hyperphagia . In addition , the expression of the
endogenous melanocortin antagonist , AgRP, which is
colocalized with NPY in the ARC ,is up-regulated during
feed restriction and lactation in sheep

9.  Diagram pdf 11486

10. SOCIAL BEHAVIOUR
 A set of brain areas in the basal forebrain and mid
brain have been identified as being involved in the
multiple forms of social behaviour (aggression ,
affiliation , bonding , parental behaviour , social
stress)and to have bidirectional connections between
pair
 These areas include Extended medial amygdala
namely medial amygdala and Bed Nucleus Of Stria
Terminalis(BNST) , The Lateral septum , the Preoptic
area ,the anterior Hypothalamus , ventromedial
hypothalamus , periaqueductal grey in the mammals

11.  Table
 Fig

12. Hormones acting on Social
behaviour

13.  Social behaviour neural network encodes information
in a distributed and dynamic fashion , it is reflected by
overall activation across the different loci in the
network rather than by activity of as single node
 Vasopressin and oxytocin are synthesized in two
different cell groups viz;
1)Magnocellular cells of the supraoptic and
paraventricular hypothalamus
2)parvocellular neurons within the paraventricular
hypothalamus and in the bed nucleus of the stria
terminalis, the medial amygdala and the
suprachiasmatic nucleus, which project to the limbic
system

14.  The two cells have different function .OT and AVP
hypothalamic magnocellular cells project to the
posterior pituitary and these pathways are responsible
for peripheral systemic effects of these neuropeptides
 where as the AVP and OT parvocellular cells project to
limbic areas including several of the nodes of social
behaviour neural network and this system is
responsible for central effects on brain
 AVP and OT may also affect expression of behaviour
through reciprocal interactions with dopaminergic
rewarding system and serotonergic system .
 Therefore the hormonal modulation of social
behaviour may occur at multiple points and at several
levels of integration .

16.  All of these may occur in different compartments of
neural circuits underlying behaviour , therefore
affecting the perception , the valance and the salience
of social behaviour.
 OT --- Parasympathetic system ---stimulate prosocial
behaviour
 AVT---sympathetic---social withdrawal and or
aggression

18. Maternal Behaviour
 Responses or behaviours displayed by female to support the
development and growth of her offspring
 Medial preoptic area (MPOA) is identified as a key
integrative site where hormones interface with hormone
receptors to stimulate the onset of maternal care as well as
in this area serving as an integral component of ongoing
maternal behaviour (numan)
 Amygdala and Nucleus accumbus –ventral pallidum (NA-
VP)circuits are involved in both mother-infant bonding or
bonding with a mating partner formation and dopamine
and oxytocin action with NA appears to promote synaptic
plasticity that allows either infant or mating partner
stimuli persistently activate NA-VP circuits, Leading to an
enduring social attraction and bonding
 (m numan ,l.j.young)

19. Olfaction association

20.  Hormones ; Estrogens , progesterone , prolactin and
placental lactogens
 Neurochemical Regulators ; Oxytocin , Arginine
vasopressin (AVP), Dopamine , Norepinehrine ,
Serotonin(5HT)
 Maternal Aggression ; GABA , AVP, Oxytocin,
CRH,&NO –these are implicated in aggressive
maternal behaviour
 An example of maternal behaviour in sheep is given
next

21. Maternal behaviour in sheep
 In sheep it is under the major influence of amniotic fluids
which cover the lamb at birth ,shift towards amniotic fluids
is mediated by chemosensory stimuli .
 Main olfactory bulb(MOB) is involved ,the odour profile
(133 volatile organic compounds )
• The changes in the MOB mitral cells at parturition is under
the influence of two Neurotransmitters – GABA
(inhibitory)and glutamate (excitatory).Once a selective
bond is established with the lamb, the odour of familiar
lamb increases the release of these transmitters
• Noradrenaline release is also increased at birth induces
disinhibition of MOB mitral cells from GABA effect , thus
potentiating glutamatergic system

23. Hypothalamic –pituitary axis

24. Agonistic/Aggressive Behaviour
Control mechanisms of Androgens
 Endocrine system controls among other systems ,the
plasma conc. Of Androgens via the feedback
mechanisms in which the hypothalamus , pituitary
gland and several hormones are involved
 Two NE circuits are of major importance in the control
of agonistic behaviour :
 a)hypothalamus –Ant. Pituitary-testes-hypothalamus
 b)hypothalamus--Ant. Pituitary-adrenocortices-
hypothalamus

26. Effect of Androgens on CNS
• Males are usually more aggressive than females ,fights
between the males often commence at puberty and in
breeding season when plasma conc. Of testosterone are
relatively high
• Two concepts are there;
1) Organisation /activation model :
• Exposure to testosterone during a critical period perinatally
or neonately has an organising effect on the developing
brain .
• Adult male animals with perinatally or neonatally
organized brains have been found to react more
aggressively under the influence of testosterone and
appropriate aggression eliciting env. Stimuli

27. 2)Sensitivity model :
 Exposure to androgen at any time of life may increase
the sensitivity of the brain to these steroids . It is
hypothesized , however , that the sensitivity of neural
tissue to androgens is inversely proportional to the
time between birth and initial exposure to androgens
The characterization of the neural circuits that control
aggression is difficult as these circuits regulate other
social behaviours
• It has been suggested that aggressive behaviours are
emergent properties of a social behaviour network that
includes MPOA ,Lateral septum (LAS),AH ,VMH
,BNST(Randy j nelson et al 2007)

29. Reproductive Behaviour
 We will be discussing some specific rather than the
general reproductive behaviours ,which we all are
aware about .
 Photoperiodic regulation of seasonal reproduction
 Male induced ovulation in sheep (Ram effect)
 Reproductive NE pathways of social behaviour

30.  Photoperiod (day length)
 Photoperiodism
 Animals respond to the photoperiod (long or short)to
breed at a time in the year when the survival of the
young ones is maximized
 Animals with short gestation period -breed in summer
 Animals with long gestation period -breed in
winter(sheep)
 The interaction between the photoperiod and
circadian clock that reads the successive phases of
light and dark , leads to the photoperiodic response
Photoperiodic regulation of
seasonal reproduction

31.  The seasonal response is regulated by
H-P-G axis/photoperiodic axis which is given next
• Recently RF-amide kisspeptin and RFRP3(RF-amide
related peptide )are believed to be regulators of HPG
axis that stimulate GnRH neurons

33. Seasonal breeding

35. Male induced ovulation in sheep
 Ability of rams to stimulate reproductive activity
among a flock of ewes
 The presence of male causes successive bursts of LH
pulses which are sufficient to promote overian
follicular development through the positive feedback ,
LH surge and ovulation
 Kisspeptin role: recently it has been showen that
central infusion of kisspeptin antagonist in advance
abolished the effect of male exposure on LH secretion,
suggesting that the male effect is mediated by
Kisspeptin signalling in ewes(De bond ja et al 2013)

37. Neural Pathway

38. Reproductive NE pathways of social
behaviour
 Reproductive functions are controlled by the HPG axis
 In recent years the role of neuropeptides containing
C-terminal Arg-Phe-NH2(RFamide peptides )has been
emphasized in vertebrate reproduction
• In particular ,kisspeptin and GnIH emerged as critical
regulators (accelerator & suppressor respectively) of
vertebrate reproduction .

39.  Social behaviours are key components of reproductive
functions , because they are essential for successful
fertilization .
 As social behaviours such as courtship ,mating and
aggression are strongly associated with sex steroids ,
hypothalamic neuropeptides can regulate social
behaviour by regulating HPGaxis