Navigation Links
Adolescent but not adult hamsters are more aggressive on low dose of fluoxetine

New research offers tantalizing clues as to why some teenagers taking common anti-depressants may become more aggressive or kill themselves. The research is published in the October Behavioral Neuroscience, which is published by the American Psychological Association (APA).

Neuroscientists at the University of Texas at Austin found that juvenile hamsters given low doses of fluoxetine hydrochloride, which is sold in the United States as Prozac, became more aggressive on low doses of the drug. Juveniles given high doses became somewhat less aggressive, but not as much as adult hamsters, who calmed down on both high and low doses.

Doctoral student and lead author Kereshmeh Taravosh-Lahn, BA, says the findings confirm that juvenile and adult brains are different. Thus, she says, "It is unwise to expect a drug to work the same in juveniles as in adults."

Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), is the only medication approved to treat depression in children and adolescents. However, it has carried an FDA "black box" warning since Fall 2004 due to findings of increased risk of suicidal thoughts and behaviors in some children and adolescents on the drugs. Fluoxetine affects the regulation of serotonin, a naturally occuring neurotransmitter thought to be involved in depression, by keeping it available longer in the brain's synapses. It is known to inhibit aggression in adult hamsters. Hamsters are often used as an animal model for studying the neural basis of social behavior, given how the rodents' youthful play fighting develops in clearly understood stages into adult aggression.

In the study, researchers injected each of the experimental hamsters with high or low doses of fluoxetine. Two hours later, they put a smaller, younger same-sex hamster into the experimental hamster's home cage for 10 minutes, creating a threatening situation to which male hamsters usually respond with aggression. The neurosc ientists videotaped the encounters to document behaviors such as attacks, pins, contact time, contact bouts and target of attack.

The adult hamsters treated with either dose of fluoxetine became generally more peaceful, attacking less often and for shorter times. However, the juveniles responded differently, both to high and low doses. The low doses actually resulted in significantly longer, more frequent and intense attacks, whereas the high dose only partly inhibited aggression. Neither set of juveniles responded as well as adults; one set (low dose) actually did worse.

Thus, although fluoxetine consistently calmed the adults in a potentially threatening situation, it differentially affected the juveniles. The effects of fluoxetine on aggressive responses appear to be specific to both age and dose.

The authors say their data add to growing evidence that during puberty, the brain is still maturing and, says Taravosh-Lahn, "could possibly react to drugs given to adults in different and potentially negative ways. We need to understand how these drugs will affect the developing nervous system before giving them to children."

The neuroscientists explain that because adolescents may have lower levels of serotonin than adults, there may not be enough of it in their systems for the SSRI to work effectively. In addition, the researchers are investigating whether changing ratios of different subtypes of serotonin receptors ?some of which inhibit and some of which enhance aggression -- are implicated in the findings of higher aggression on low doses.

Source:American Psychological Association

Related biology news :

1. Recent breakthroughs in common adult leukemia highlighted in New England Journal of Medicine
2. Study finds adult stem cells can replicate
3. Researchers discover mechanism for multiplying adult stem cells
4. Suppressing growth hormone in early adulthood may prevent cancer
5. A new window into structural plasticity in the adult visual cortex
6. MIT researcher finds neuron growth in adult brain
7. New neurons take baby steps in the adult brain
8. Neurons generated in the adult brain learn to respond to novel stimuli
9. Changes to embryos can elicit change in adult fish
10. Feds give researchers ok for safety test of adult stem cells in patients with heart disease
11. HIV-infected adults in Botswana respond positively to ARV therapy public treatment program

Post Your Comments:

(Date:11/2/2015)... PARK, Calif. , Nov. 2, 2015  SRI ... $9 million to provide preclinical development services to the ... the contract, SRI will provide scientific expertise, modern testing ... wide variety of preclinical pharmacology and toxicology studies to ... --> The PREVENT Cancer Drug Development ...
(Date:10/29/2015)... ANN ARBOR, Mich. , Oct. 29, 2015 ... with Eurofins Genomics for U.S. distribution of its ... DNA-seq kit and Rubicon,s new ThruPLEX Plasma-seq ... DNA to enable the preparation of NGS libraries ... in plasma for diagnostic and prognostic applications in ...
(Date:10/27/2015)... , Oct. 27, 2015 In the ... issues of concern for various industry verticals such as ... due to the growing demand for secure & simplified ... various ,sectors, such as hacking of bank accounts, misuse ... electronic equipment such as PC,s, laptops, and smartphones are ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... 24, 2015 --> ... report released by Transparency Market Research, the global non-invasive ... CAGR of 17.5% during the period between 2014 and ... Global Industry Analysis, Size, Volume, Share, Growth, Trends and ... testing market to reach a valuation of US$2.38 bn ...
(Date:11/24/2015)... ... 24, 2015 , ... InSphero AG, the leading supplier of easy-to-use solutions for ... Aregger to serve as Chief Operating Officer. , Having joined InSphero in ... and was promoted to Head of InSphero Diagnostics in 2014. There she ...
(Date:11/24/2015)... VILLAGE, Nev. , Nov. 24, 2015  PDL BioPharma, ... John P. McLaughlin , the company,s president and chief executive ... Jaffray Healthcare Conference next week in New York ... will occur on Tuesday, December 1, 2015 at 9:30 a.m. ... Presentations." Please connect to the website at least 15 minutes ...
(Date:11/23/2015)... Calif., Nov. 23, 2015   Ceres, Inc . ... today financial results for the fiscal year ended August ... --> --> During ... forage and feed products with a better balance of ... signed distribution agreements with several leading crop input providers ...
Breaking Biology Technology: