A study indicate a molecular mechanism involving the OPRM1 gene that may play a role in diseases characterized by deficits in attachment behavior, such as autism or reactive attachment disorder (Moles, Kieffer and D'Amato 2004).
Molecular Function
The encoded protein has mu-opioid receptor activity.
External Links
References
Type
Title
Type of Disorder
Associated Disorders
Author, Year
Primary
Deficit in attachment behavior in mice lacking the mu-opioid receptor gene.
Oprm1 is involved in G-protein coupled receptor activity and voltage-gated calcium channel activity; mice with homozygous null Oprm1 deletion have deficits in sociability and communication;.
References
Type
Title
Author, Year
Primary
Region specific up-regulation of oxytocin receptors in the opioid oprm1 (-/-) mouse model of autism.
Model Type:
Genetic
Model Genotype:
Homozygous
Mutation:
Oprm1 null mice were generated by disruption of exon 2 in the Oprm1 gene, and housed with their own lactating mother until weaning at P28;.
Allele Type: Targeted
Strain of Origin: Unreported
Genetic Background: C57BL6/J
ES Cell Line: Unreported
Mutant ES Cell Line: Unreported
Model Source: Animal facility at IRCCS Santa Lucia Foundation, Rome, Italy
Description: Compared to wildtype controls oprm1 homozygous null mice display increased oxytocin receptor (oxtr) expression selectively in the medial anterior olfactory nucleus (aon)
Exp Paradigm: Brain regions were selected on the basis of co-expression of oxtr and mu opioid receptors (mor); nissl staining and acetylcholinesterase (ache) staining was done to identify brain regions; quantitation was based on iodine-125 incorporation;
Description: Compared to wildtype controls oprm1 homozygous null mice display increased oxytocin receptor (oxtr) expression in the anterior nuclei of the amygdala (central anygdaloid nucleus- cea and medial amygdaloid nucleus-mea)
Exp Paradigm: Brain regions were selected on the basis of co-expression of oxtr and mu opioid receptors (mor); nissl staining and acetylcholinesterase (ache) staining was done to identify brain regions; quantitation was based on iodine-125 incorporation;
Description: Compared to wildtype controls oprm1 homozygous null mice display increased oxytocin receptor (oxtr) expression selectively in the nucleus accumbens (nacc)
Exp Paradigm: Brain regions were selected on the basis of co-expression of oxtr and mu opioid receptors (mor); nissl staining and acetylcholinesterase (ache) staining was done to identify brain regions; quantitation was based on iodine-125 incorporation;
Description: Although a general analysis showed oprm1 homozygous null mice were able to recognize partners' familiarity during repeated exposures according to reduction in time spent investigating the partners during successive sessions, a sex based analysis showed male oprm1 homozygous null mice had significantly reduced capacity in distinguishing an unknown from a familiar mouse compared to wt mice
Exp Paradigm: Partners were younger mice, p45-70; 5 consecutive 1 min interaction sessions; the same intruder was used for the first four sessions and an unknown one was used for the 5th session;
Description: Oprm1 homozygous null mice spent less time close to the conspecific mouse than the object compared to wildtype controls;
Exp Paradigm: Measured following, sniffing nose, body, and ano-genital region of the partner
Description: Male oprm1 homozygous null mice spent less time in social investigation than wt mice;
Exp Paradigm: Partners were younger mice, p45-70; 5 consecutive 1 min interaction sessions; the same intruder was used for the first four sessions and an unknown one was used for the 5th session;
Description: Oprm1 homozygous null mice spent less time close to the conspecific mouse than the object compared to wildtype controls;
Exp Paradigm: Animals tested before weaning; a conspecific nmri mouse, age and sex matched was used as stimulus;
Description: Male oprm1 homozygous null mice had reduced capacity in distinguishing an unknown from a familiar mouse compared to wt mice, during serial presentation of the intruder in the resident intruder test
Exp Paradigm: Partners were younger mice, p45-70; 5 consecutive 1 min interaction sessions; the same intruder was used for the first four sessions and an unknown one was used for the 5th session;
Description: Total time spent close to partners was not affected in oprm1 null mice compared to wt mice of either genders; female oprm1 null mice showed similar interest toward their female partners whether the latter were oprm1 null mice or wt mice; male oprm1 null mice showed preference of males of the alien (wt genotype) compared to oprm1 null mice partners whereas wt males showed avoidance of the males of the alien line (oprm1 null mice);
Exp Paradigm: Subject was simultaneously exposed to mice with different genotypes
Description: Oprm1 ko pups reared by their own mother in a clean cage emitted significantly fewer number of ultrasonic vocalizations than wildtype controls in a clean cage with a single mother; there was no effect of sex on ultrasonic emissions; there was no difference between home-cage and clean bedding exposure on oprm1 ko mice;
Exp Paradigm: After 1h acclimatization to the room, mother was removed, pups were left in the home cage; pups (one male and one female) were then placed in a beaker containing bedding from their own cage or clean bedding and vocalizations recorded;
Ultrasonic vocalization: interaction induced: opposite sex stimulus1
Decreased
Description: During male and female social interaction, oprm1 null males emitted reduced number of ultrasonic vocalizations;
Exp Paradigm: Only male behavior tested, independent of the female receptivity; five minutes after the males intranasal drug/saline administration, a female of the same genotype was introduced into the males home cage and left for 5 min; oprm1 null males were exposed to oprm1 null females and wt males to wt females;
