**2. PDs and animal models**

*Animal Models in Medicine and Biology*

Pre-pulse inhibition

Working memory and learning

Sucrose preference

test

**Table 1.**

(PPI)

**60**

construct validity.

of the neural neurobiological substrates and their circuit dysfunctions [18]. Thus, it has been demonstrated that the modeling of neurobiological and behavioral endophe-

**Endophenotype Description What can be evaluated**

Behavioral sensitization (BD; ADHD; SCZ); Depressive-like behaviors (MDD); etc…

Cognitive impairments

Cognitive impairments

Cognitive impairments (PDs in general); etc…

Anxiety-like behaviors; Depressive-like behaviors;

Anxiety-like behaviors; Depressive-like behaviors;

Anxiety-like behaviors; Depressive-like behaviors;

Depressive-like behaviors;

Depressive-like behaviors;

Cognitive impairments (PDs

Depressive-like behaviors;

in general); etc…

Anxiety-like behaviors; etc…

(SCZ); etc…

(SCZ); etc…

etc…

etc…

etc…

etc…

etc…

etc…

of the movements measured during or after a habituation period or after some stimuli (i.e.

nonreinforced stimulus to inhibit later stimulus-

Decrease of the startle reflex after exposure to a

Describes short-term memory, in a olfactory

exploratory behavior induced by a drug or/and

cleaning of the fur; is displayed as reaction to unexpected stimuli and in conflict situations

Food intake Amount of food ingested by the animal Anxiety-like behaviors;

Assesses the sensitivity to reward based on the rodent's natural preference for sweets. This test measures the amount of a sweet-tasting solution

aversive stimulus is paired with some neutral stimuli. Used to assess associative fear learning

climbing (active behavior), and immobility (passive behavior) when animals are placed in an inescapable cylinder filled with water

*Most common endophenotypes used to evaluate behaviors associated with psychiatric disorders (PDs).*

reaction to a stimuli or other animal

Locomotor activity Distance travelled, time spent, and frequency

drug administration)

Latent inhibition Latent inhibition is the ability of a pre-exposed

pre-pulse before the pulse

domain and spatial domain

Social interaction Evaluation of time spent on exploring a social stimulus.

Rearing Measure of activity, investigation and

Grooming A maintenance behavior evaluated by the

Aggressiveness Evaluation of attack and defensive behavior as

that the animal ingests

and memory in rodents.

Fear conditioning Classical conditioning paradigm, in which an

Forced swim test Measures the scoring of swimming and

novelty

response learning

The ideal animal model should be derived from risk factors or the causative agent of the human disease. One of the strategies used during the construction of a model is focused on a specific factor that can reproduce the condition as a whole or an aspect of the disease [19]. The choice for the methodology used in establishing a model is fundamentally important to guide which aspect of the disease should be explored, and it is an essential component in the validation of a model known as

notypes to reproduce PDs in experimental animals is possible.

In the following sections, selected examples of animal models used in the context of investigating PDs will be demonstrated, indicating which changes are observed in behavioral and molecular levels.
