An Introduction to Selective Breeding

Program With Rats

By

Waseem Hassan

Objective !!!!

Write down a Review….

Comprising 8-10 different breeding lines..

Focusing on their behavioral profile.

Selective Breeding Program

Bi-directional selective breeding of organisms

has been successful in many different

species and for a wide variety of anatomical,

physiological and behavioral phenotypes.

Anatomical Reasons

Brain weight,

Tooth width, and

Abdominal bristle number

Physiological Reasons

Rate of electrical self-stimulation of the brain

Duration of alcohol-induced loss of righting reflexalso known as ‘sleep time’

Susceptibility to, and/or severity of, seizures

Behavioral Reasons

Avoidance learning

Maze learning

Emotionality

Latency to copulate

Voluntary consumption of alcohol

Locomotor activity

Objective of Selective Breeding

In a broad sense the objective is….

To Separate lines carrying,

the distinct characteristics of a particular disease or

pathological disorder.

In this seminar….

High and Low Anxiety behavior Rats (HAB/LAB)

Roman High and Low Avoidance Rats

Floripa High and Low Lines

The focus will be on their behavioral Profile.

Behavioral Profile ..

Defecation in Open Field

Time Open Arms (EPM)

Time in Central Area (OF)

Floating Time (FST)

Active avoidance

Time in Social Interaction

Basal Corticosterone

Voluntary Ethanol Intake

The Floripa Lines Andre Ramos in 2003,

Quest for a better genetic model. For the study of stress and anxiety. New line of wistar rats. The main objective !!!!!! To develop, through selective breeding,

two new rat lines differing in locomotion in the center of the open field.

Open Field.

After four generations of selection,

the differences between the Floripa H and L rat lines regarding

locomotion in the center of an open field

As expected (H) lines displaying a higher locomotion in the central area of the

open field than rats of the (L) lines.

Elevated plus maze In the elevated plus maze,

After four generations The Rats of the H line spent

More time in the open arms than L-line rats.

Similarly,

Rats of the H line made Higher number of entries into the open arms

than L-Lines.

Entries in closed arms for both lines was not significantly different in initial breeding generations but

later appeared in fourth generation

where H rats showed a greater number of entries than L rats.

To Note…….

Black and white box

In the black and white box (H) rats spent more time in the white compartment

than L rats after four generation.

Floripa (H) lines also showed higher locomotion in Tha Floripa (L) lines.

High (H) lines made more transitions than Low lines in fourth generation.

Ethanol uptake

1)…Ethanol up take ,

No difference between the lines, however female drunk more…

2)…Ethanol Preference ,

No Line difference, however females have more preference for ethanol.

1)…Ethanol up take ,

2)…Ethanol Preference ,

Conclusion from ethanol uptake … Females have more ,

1….Tendency to drink alcohol , and

2….Preference for ethanol.

G.S. Izı´dio, A. Ramos / Alcohol 41 (2007) 517e524

Izidio et al., 2007 have found that floripa L

females consumed more ethanol than their

floripa male counterparts.

Forced swim test (L) lines line spend more time immobile

than floripa (H) ..i.e. 6th Generation

7th Generation… FST

SUMMARY

The present study demonstrates theimportance of genetic factors in the

modulation ofanxiety-related behaviors, as well as

the efficacy of selective breeding experiments in the development of

genetic models for the study of anxiety/emotionality.

HAB/LAB…

At the age of ten weeks, rats were tested once on the elevated plus-maze and the males and females displaying the most anxious and the least anxious behaviour were sib-mated to start a new generation of the..

High anxiety-related behaviour (HAB) and, Low anxiety-related behaviour (LAB) lines,

respectively.

Elevated Plus Maze….

Black White Box…

Social Interaction

Home cage behavior..

Ethanol Intake…

Daily ethanol intake (upper panel) and preference (lower panel) of female HAB and LAB rats

Endocrine function..

Endocrine function

Landgraf et al., in 2002 reported that HAB and LAB rats do not differ in their anxiety like behavior but also in their stress vulnerability and secreted more adrenocorticotropin (ACTH) and corticosterone indicative of hypo-thalamo-pituatary-adrenocortical (HPA) axis. However social defeat data of Frank et al., 2006 reported an interesting observation, he found that heightened trait anxiety can make rats more prone to stress and he measured higher levels of ACTH and Corticsterone in LAB as compared to HAB suggesting the possibility of stimulus dependent dissociation between behavioral and neuroendocrine stress responses. Salomé et al., 2004 al., also reported, that HPA-axis reactivity is more pronounced in HAB than LAB rats when exposed to mild stressors, including an open arm of the EPM or an open field.

Forced Swim Test…

Conclusion..

The overall performance in these various behavioural tests suggests that selective breeding has resulted in rat lines not only differing markedly in their innate anxiety-related behaviour in the plus-maze, but also in other stress-related behavioural performances, suggesting a close link between the emotional evaluation of a novel and stressful situation and an individual’s coping strategy

Roman High vs Roman low active avoidance strains

Bignami et al., in 1965 started a series of experiments where rats from normal wistar population were tested for high and low rates of active avoidance conditioning in a shuttle box. After five generations, the two selected lines [Roman High Avoidance (RHA) and Roman Low Avoidance (RLA)] differed markedly (at least threefold differences) in the number of avoidances during the trials and this effect gender independent.

Defecation When exposed to a novel environment (or various

other stressors) RLA/Verh rats show more pronounced emotional responses such as more defecation. Taken a step ahead in this work when RLA/Verh were tested in six different test situations which involved either novelty or an approach/avoidance conflict Ferré et al. observed higher defecation for RLA/Verh strains.

However N. Castanon observed no difference in defecation scores in both lines, an interesting observation.

Ferré, P., et al. 1995. Physiol. & Behav. 58: 1209–1213. N. Castanon et al, Physiol. Behav. 51 (1992), pp. 1235–1241.

Behavioral tests

Exposure to various stressors induces a more pronounced emotional response in RLA/Verh rats, such as higher levels immobility, than in RHA/Verh rats. Similarly C. Gentsch, found RHA/Verh rats more active than RLA/Verh rats in the open field. In contrast RHA/Verh line are "active copers and taking more risks and being willing to drink strange, and sometimes even aversive, liquids,

Refs..on next page

Driscoll, P. & K. Baettig. 1982. In Genetics of the Brain. I. Lieblich, Ed.: 95-123. Elsevier Biomedical Press. Amsterdam.

Escorihuela, R. M., et al. 1995. Neurosci. Biobehav. Rev. 19: 353–367.

Steimer, T., 1997. J. Neuroendocrinol. 9: 169–175.

Fernández-Teruel, A., et al. 1991. Physiol. Behav. 50: 563–565.

C. Gentsch, Physiol. Behav. 27 (1981), pp. 183–186.

Fernández-Teruel, A., et al. 1992. Neurosci. Lett. 137: 185–188.

Ferré, P., et al. 1995. Physiol. & Behav. 58: 1209–1213.  

Razafimanalina, R., 1996. Behav. Pharmacol. 7: 78–84.

EPM

EPM Continued…

Endocrine i.e. CORTICOSTERONE and ACTH differences

Walker et al., in 1989 examined the activation of the pituitary-adrenal axis in both RHA and RLA rats. He found that Basal plasma ACTH concentrations were lower in RLA than in RHA rats (RLA: 110·8 ± 24·5 ng/l; RHA: 252·7 ± 60·8 ng/l, P<0·05). Similarly , corticosterone and aldosterone under resting conditions were not different between RLA and RHA rats. But after open field (stress) Plasma corticosterone was significantly higher in RLA (P<0·05). Apart from this Numerous studies have shown that the Roman lines differ in the hypothalamus–pituitary–adrenocortical (HPA) axis .However N. Castanon observed no difference in corticosterone and ACTH concentrations, before or after exposure to the open field in both strais. Castanon extended his work and later reported no differences in the reactivity of the HPA axis (ACTH and corticosterone) to psychological (open field) or physiological (CRF) stimulation in 14-week old Roman rats. In the same study the corticosterone response to a stressful situation was not correlated with the avoidance behaviour in the shuttle box.

Walker, C. D., et al. 1989. J. Endocrinol. 123: 477–485

J. M. Aubry, VNeuroendocrinology 61 (1995), pp. 89–97.

C. Gentsch, Physiol. Behav. 28 (1982), pp. 259–263.

C. Gentsch, Experientia 44 (1988), pp. 482–490.

Steimer, T., 1997. Behav. Genet. 27: 503–512.

N. Castanon, Physiol. Behav. 51 (1992), pp. 1235–1241.

N. Castanon, Physiol. Behav. 55 (1994), pp. 775–782.