DIMORFISMO SESSUALE DELLE

PATOLOGIA DEL SISTEMA NERVOSO:

POSSIBILI TARGETS TERAPEUTICI

GENDER DIFFERENCES IN ALZHEIMER’S

DISEASE

Epidemiological studies support a higher prevalence and incidence in women

(Moreira et al., 2008)

At variance, to what observed in young male and old females, mitochondria of

young females are protected against the increased in peroxide production caused

by β-amyloid (Lloret et al., 2008)

Higher plaque load is observed in female than in male (Callahan et al., 2001)

In experimental models aged female animals are more sensitive to kainic acid.

Thus, females show increased hippocampal neurodegeneration, enahanced

astrocyte proliferation and higher levels of BDNF in hippocampus (Zhang et al.,

2008)

GENDER DIFFERENCES IN PARKINSON’S

DISEASE

The incidence is greater in men than in women (Benito-Leon et al., 2003; de Lau

et al., 2004; Van Den Eeden et al., 2003; Wooten et al., 2004).

Course and symptoms as well as pharmacological treatment are also gender

different (Fernandez et al., 2000; Haaxma et al., 2007; Homann et al., 2003;

Martinelli et al., 2003; Zappia et al., 2005).

Women tend to be older than men at symptom onset and present more often than

men a tremor dominant form of disease, which in turn is associated with a slower

disease progression. Moreover, at onset of the disease they have higher levels of

striatal dopamine binding than men (Haaxma et al., 2007).

GENDER DIFFERENCES IN EXPERIMENTAL

MODEL OF PARKINSON’S DISEASE

In mice model, male animals show a stronger depletion of dopamine

after intoxication with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

(MPTP) than female animals (Czlonkowska et al., 2006).

Inflammatory processes could have a role in this gender dependent

event. Namely, different gene expression profiles of pro-inflammatory

molecules, such as TNF , IL-6, IFN , IL-1 , occur in male and

female animals after MPTP injection (Czlonkowska et al., 2006).

SEX DIFFERENCES IN MULTIPLE SCLEROSIS

Multiple Sclerosis is more frequent in female than in male (ratio 2:1)(Noonan et al., 2002; Houzen et al., 2003; Orton et al., 2006; Schwendimann and Alekseeva, 2007 )

The disease mainly affects young and postpubertal women and most

commonly causes relapsing-remitting-type symptomatology.

Therefore, women showing a benign course (Hawkins and McDonnell, 1999)

Men have a worse prognosis. Indeed, they are affected in older age

and develop a more severe pathology, defined as a shorter time to

reach severe disability (Confavreux et al., 2003)

SEX DIFFERENCES IN SCHIZOPHRENIA

The risk is comparable, but sex differences occur in age of onset and

in course of the disease as well as in the response to treatment (Hafner,

2003; Halbreich & Kahn, 2003; Rao and Kolsch, 2003; Riescher-Rossler & Hafner, 2000)

Men usually experience first onset between 15 and 24 years. This is

about 3-4 years earlier than in women. A second increase of the

incidence occurs only in women between 45 and 54 years.

Men show more severe negative symptoms than women.

Women react better to antipsychotic therapy than men.

Functional (FMR) and morphometric studies show sex differences.

SEX DIFFERENCES IN AUTISM

Clinical and epidemiological studies indicate that boys are affected

more frequently than girls (ratio 4:1) (Fombonne, 1999, 2003;Volkmar

et al., 1993)

Male heterozygous reeler, at variance with female, have a reduced

number of Purkinje cells (Doulazmi et al., 1999; Hadj-Sahraoui et al.,

1996; Biamonte et al., 2009)

WHAT CAUSES PERIPHERAL NEUROPATHY?

Physical injury (trauma)

Systemic diseases:Diabetes mellitus

Kidney disorders

Hormonal imbalances

Vitamin deficiences

Alcoholism

Vascular damage and blood diseases

Connective tissue disorders and chronic inflammation

Cancers and benign tumors

Repetitive stress

Toxins

Infections and autoimmune disorders

Inherited forms of peripheral neuropathy

GENDER DIFFERENCES IN DIABETIC

NEUROPATHY

Diabetic neuropathy is more frequent in men than in women(Basit A. et al., 2004; Booya F. et al, 2005)

Males develop neuropathy approximately 4 years earlier than females(Aaberg M.L. et al., 2008)

Neuropathic pain and negative sensory symptoms are more frequent in

female, whereas atrophy is more frequent in male patients(Kiziltan M.E. & Benbir G., 2008)

Motor nerve conduction abnormalities and ulnar nerve involvement is

also more frequent and severe in males(Albers J.W. et al, 1996; Kiziltan M.E. et al., 2007; Kiziltan M.E. & Benbir G., 2008)

STEROID HORMONES

NEUROSTEROIDS

ENDOCRINE

PARACRINE AUTOCRINE

O

OH

O

HOH

O

O

5 -reductase

3 -hydroxysteroid-dehydrogenase

Progesterone

5 -pregnan-3,20-dione

(dihydroprogesterone, DHP)

5 -pregnan-3 -ol-20-one

(tetrahydroprogesterone, THP)

OH

HO H

O

OH

OH

OH

5 -reductase

3 -hydroxysteroid-dehydrogenase

Testosterone

5 -androstan-17 -ol-3-one

(dihydrotestosterone, DHT)

5 -androstan-3 ,17 -diol

(3 -diol)

CLASSICAL AND NON CLASSICAL

STEROID RECEPTORS

PROGESTERONE RECEPTOR

ANDROGEN RECEPTOR

ESTROGEN RECEPTOR

GLUCOCORTICOID RECEPTOR

MINERALOCORTICOID RECEPTOR

GABA-A RECEPTOR

GABA-B RECEPTOR

NMDA RECEPTOR

AMPA RECEPTOR

KAINATE RECEPTOR

SIGMA 1 RECEPTOR

Are gender differences in

neurodegenerative disorders

related to neuroactive

steroids?

In female rats, the fluctuation in hormonal levels during

estrous cycle affects the response of the brain to pathological

insults. For instance, neurotxic effect of kainic acid on

hippocampus of intact females rats is different depending on

the day of the estrous cycle on wich the neurotoxin is injected

(azcoitia et al. 1999).

Morning of estrous (i.e. 1 days after the peak of

estrogen)………No neuronal loss

Morning of proestrus (when peak of estrogen occurs) ……….

Loss of neurons

Ovariectomized rats …………..Loss of neurons

In premenopausal women parkinsonian symptoms have been

reported to worsen at the onset of menses, when estrogen

levels are low (Quinn & Marsden 1986).

Postmenopausally hormone replacement therapy has been

reported to improve symptoms (Saunders-Pullman et al.

1999), with a worsening on withdrawal of treatment (Sandyk

1989).

Women who underwent oophorectomy before the onset of

menopause had increased risk of parkinsonism compared

with referent women and he risk increased with younger age

at oophorectomy (Rocca et al, 2008).

MULTIPLE SCLEROSIS

(EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS)

SEX STEROIDS

MENSTRUAL CYCLE PREGNANCY MENOPAUSE

ASSESSMENT OF NEUROACTIVE STEROIDS BY LIQUID

CHROMATOGRAPHY –TANDEM MASS SPECTROMETRY

SPINAL CORD CEREBELLUM CORTEX SCIATIC NERVE PLASMA

PREG

PROG

DHP

THP

Isopregnanolone

T

DHT

3α-diol

DHEA

17β-estradiol

= = =

=

= =

=

= = =

u.d.l

u.d.l

= =

imm

uniz

atio

n

scor

e

0

1

2

3

4

5

relapseacute remission

Dark-Agouti rat

sco

re/s

ectio

n

0

10

20

30

40

50

60

*

MEAE FEAE

(6)

(6)

PREGNENOLONE

PROGESTERONE

DIHYDROPROGESTERONE

TETRAHYDROPROGESTERONE

ISOPREGNANOLONE

TESTOSTERONE

DIHYDROTESTOSTERONE

3ALPHA-DIOL

EFFECT OF EAE ON NEUROACTIVE STEROID LEVELS

SPINAL CORD PLASMA

DHP

THP

ISOPREGNANOLONE

PROG receptor

GABA-A receptor

DHT 3ALPHA-DIOL

AR GABA-A receptor ER BETA

PREGNENOLONE

PROGESTERONE

DIHYDROPROGESTERONE

TETRAHYDROPROGESTERONE

ISOPREGNANOLONE

TESTOSTERONE

DIHYDROTESTOSTERONE

3ALPHA-DIOL

EFFECT OF DIABETES ON NEUROACTIVE STEROID LEVELS

SCIATIC NERVE

pg

/mg

tiss

ue

M MF F

WT HZ

pg

/mg

tiss

ue

0

10

20

30

40

50

60

70

0

5

10

15

20

25# #

M MF F

WT HZ

pg

/mg

tiss

ue

0

10

20

30

40

50

60

70

M MF F

WT HZ

pg

/mg

tiss

ue

#§

M MF F

WT HZ

0

25

50

pg

/mg

tiss

ue

0

pg

/mg

tiss

ue

M MF F

WT HZ

M MF F

WT HZ

§ #

10

20

30

40

50

60

70

§§

0

1

2

3

4

5

6

7

WT HZ WT HZ

pg

/mg

tiss

ue

0

1

2

3

4

5

6

7

M MF F

§§

pg

/mg

tiss

ue

§§

M MF F0

1

2

3

4

5

6

7

< LOQ < LOQ < LOQ

< LOQ< LOQ < LOQ < LOQ < LOQ

PREG PROG

DHP 3α, 5α THP

3β, 5α THP T

DHT 3α-diol

LOQ, limit of quantification

# P < 0.01

§ P < 0.001

pg

/mg

tiss

ue

+/+ +/+rl/+ rl/+

P5 P15

0.0

0.1

0.2

0.3

0.4

0.5

0.6

* **

0

5

10

15

pg

/mg

tiss

ue

+/+ +/+rl/+ rl/+P5 P15

****

0.00

0.05

0.10

0.15

0.20

0.25

+/+ +/+rl/+ rl/+P5 P15

pg

/mg

tiss

ue

** ***

0.1

0.2

0.3

0.4

pg

/mg

tiss

ue

+/+ +/+rl/+ rl/+P5 P15

*

< LOQ < LOQ

LEVELS OF NEUROACTIVE STEROIDS IN

MALE CEREBELLUM

TESTOSTERONE DHT

3α-DIOL 17β-DIOL

LEVELS OF NEUROACTIVE STEROIDS IN

FEMALE CEREBELLUM

0.0

0.2

0.4

pg

/mg

tiss

ue

+/+ +/+rl/+ rl/+P5 P15

0

4

8

+/+ +/+rl/+ rl/+P5 P15

pg

/mg

tiss

ue

< LOQ

12

pg

/mg

tiss

ue

+/+ +/+rl/+ rl/+P5 P15

0.0

0.2

0.4*

pg

/mg

tiss

ue

+/+ +/+rl/+ rl/+P5 P15

0.08

0.04

0.00

TESTOSTERONE DHT

3α-DIOL 17β-DIOL

TESTOSTERONE

DHT 17β-Estradiol

PREGNENOLONE

CHOLESTEROL

Inner

mitochondrial

membrane

VDAC

PBROuter

mitochondrial

membrane

ADC

DBS

P450scc: cytochrome P450side-chain cleavage.

VDAC: voltage-dependent anion channel

BDS: benzodiazepine-binding site

ADC: adenine nucleotide carrier

A WORKING MODEL OF PBR FUNCTION

CHOLESTEROL

PREGNENOLONE

This step of trasporting

cholesterol from cytoplasm

into the inner mitochondrial

membrane is the primary point

of control in the acute

stimulation of steroidogenesis

Steroid synthesis

CONCLUSIONS

-The levels of neuroactive steroids present in male and female CNS

are different in control animals and differently affected by pathology.

-These modifications may affect the result of therapy based on

neuroactive steroids and may suggest new therapeutic strategies.

-The findings here reported may represent an important background

for new sex oriented therapy neuroactive steroid-based for

neurodegenerative disorders.