lecture 8 - outline · lecture 8 - outline endocrine systems ii 1. nomenclature & anatomy 2....
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LECTURE 8 - OUTLINE
Endocrine Systems II
1. Nomenclature & anatomy
2. Cytology & hormones
(I) lactotropes
Introduction
Pituitary Gland
(II) thyrotropes
(III) corticotropes
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BIOL 4340 – Lecture 8 - 1
Pituitary Gland (hypophysis)
2. Cytology and hormones
(I) lactotropes – rostral pars distalis, prolactin (PRL)
- osmoregulation
- reproduction (lactogenesis)
- may play a role in parental care
e.g. trophic provisioning
- increased mucus production
in Symphysodon spp.
BIOL 4340 – Lecture 8 - 2
Bluegill (Lepomis sp.)
- inhibition of PRL release
using bromocriptine implants
- reduced aggression
- increased ring circling
- reduced egg fanning (fungus!)
2
Pituitary Gland (hypophysis)
2. Cytology and hormones
(II) thyrotropes – rostral pars distalis, thyrotropin (TSH)
lactotropes
thyrotropes
corticotropes
gonadotropes
somatotropes
- controls thyroid gland function, thyroid hormone levels
thyroxine (T4) 3,5,3”-triiodothyronine (T3)
BIOL 4340 – Lecture 8 - 3
Pituitary Gland (hypophysis)
2. Cytology and hormones
(II) thyrotropes – rostral pars distalis, thyrotropin (TSH)
- controls thyroid gland function, thyroid hormone levels
- thyroid hormones influence most bodily functions
1. Growth 2. Differentiation 3. Metamorphosis
4. Reproduction 5. Hibernation 6. Thermogenesis
BIOL 4340 – Lecture 8 - 4
3
Pituitary Gland (hypophysis)
2. Cytology and hormones
(II) thyrotropes – rostral pars distalis, thyrotropin (TSH)
- controls thyroid gland function, thyroid hormone levels
- thyroid hormones regulate basal metabolic rate
- thyroid hormones influence most bodily functions
Migration of fishes (fasting)
- increased thyroid gland activity in
migrating Atlantic salmon
Lampetra fluviatilis
- active thyroid gland at the beginning
of breeding migration
SW FW
Th
yro
xin
e(n
g/m
l)
12
8
6
4
2
10
pre
-spaw
nin
g
post
-spaw
nin
g
BIOL 4340 – Lecture 8 - 5
Pituitary Gland (hypophysis)
2. Cytology and hormones
(II) thyrotropes – rostral pars distalis, thyrotropin (TSH)
- controls thyroid gland function, thyroid hormone levels
- thyroid hormones influence most bodily functions
1. Growth 2. Differentiation 3. Metamorphosis
4. Reproduction 5. Hibernation 6. Thermogenesis
- Black bear (Ursus americanus)
- hibernation-induced hypothyroidism
- reduced TSH & thyroid hormones
- metabolic rate very low
Hibernation
BIOL 4340 – Lecture 8 - 6
4
Pituitary Gland (hypophysis)
African lungfish estivation
BIOL 4340 – Lecture 8 - 7
- estivation may last 2 - 3 years in African lungfish
- thyroid hormone secretions become 1/75 of normal
- pituitary TSH content similar in estivating and normal fish
- hypophysectomy had no effect on estivating fish
- intact pituitary essential for survival upon emegrence
Pituitary Gland (hypophysis)
2. Cytology and hormones
(II) thyrotropes – rostral pars distalis, thyrotropin (TSH)
- controls thyroid gland function, thyroid hormone levels
- thyroid hormones influence most bodily functions
1. Growth 2. Differentiation 3. Metamorphosis
4. Reproduction 5. Hibernation 6. Thermogenesis
BIOL 4340 – Lecture 8 - 8
5
Pituitary Gland (hypophysis)
2. Cytology and hormones
(II) thyrotropes – rostral pars distalis, thyrotropin (TSH)
- controls thyroid gland function, thyroid hormone levels
- thyroid hormones influence most bodily functions
Th
yro
xin
e(n
g/g
bo
dy w
eig
ht)
14
10
6
2
0-1 2 3 3.5
Developmental Stage
Flounder metamorphosis
- stage 3.5, Juvenile
- stage 3, Metamorphosis (late)
- stage 2, Metamorphosis (early)
- stage 0-1, Premetamorphosis
BIOL 4340 – Lecture 8 - 9
Pituitary Gland (hypophysis)
2. Cytology and hormones
(II) thyrotropes – rostral pars distalis, thyrotropin (TSH)
- controls thyroid gland function, thyroid hormone levels
- thyroid hormones influence most bodily functions
Th
yro
xin
e(n
g/g
bo
dy w
eig
ht)
14
10
6
2
U T4 TU
Treatment
Flounder metamorphosis
- TU: 30 ppm Thiourea in water
- T4: 100 ppb T4 in water
- U: untreated
Altering Thyroid Status
(thiourea inhibits T4 synthesis)
BIOL 4340 – Lecture 8 - 10
6
Pituitary Gland (hypophysis)
2. Cytology and hormones
(II) thyrotropes – rostral pars distalis, thyrotropin (TSH)
- controls thyroid gland function, thyroid hormone levels
- thyroid hormones influence most bodily functions
- stage 0-1, Premetamorphosis
- stage 2, Metamorphosis (early)
- stage 3, Metamorphosis (late)
- stage 3.5, Juvenile
Flounder metamorphosis
: Control
: 100 ppb T4
: 30 ppm Thiourea
3.5
3
1.5
2.5
2
1
0.5
0
Age (dph)
Sta
ge o
f m
eta
mo
rph
osis
6030
Schreiber & Specker 1998. Gen Comp Endocrinol 111: 156-166
- experiment started 27 dph
(36 dph)
(30 dph)
(43 dph)
BIOL 4340 – Lecture 8 - 11
Pituitary Gland (hypophysis)
2. Cytology and hormones
(III) corticotropes – rostral pars distalis, corticotropin (ACTH)
head trunk
pcv
pcv – postcardinal vein
interrenal tissue
BIOL 4340 – Lecture 8 - 12
- hypothalamic-pituitary-interrenal (HPI) axis
- stimulates steroid biosynthesis & secretion, interrenals
7
Pituitary Gland (hypophysis)
2. Cytology and hormones
(III) corticotropes – rostral pars distalis, corticotropin (ACTH)
- ACTH dominates control of corticosteroid secretion
0
60
120
180
70 140 2100
co
rtis
ol
rele
ase (
ng
/h/k
g)
time (min)
ACTHMammalia
- corticosterone
- cortisol
- aldosterone
glucocorticoids
mineralocorticoids
BIOL 4340 – Lecture 8 - 13
Cyclostomes
- cortisol, corticosterone [tentative]
Pituitary Gland (hypophysis)
2. Cytology and hormones
(III) corticotropes – rostral pars distalis, corticotropin (ACTH)
- ACTH dominates control of corticosteroid secretion
Chondrichthyes
- 1α-hydroxycorticosterone
Elasmobranchii
- cortisol
Holocephali
Actinopterygii
- cortisol
Sarcoptyregii (lungfishes)
- cortisol- aldosterone
0
60
120
180
70 140 2100
co
rtis
ol
rele
ase (
ng
/h/k
g)
time (min)
ACTH
BIOL 4340 – Lecture 8 - 14