We have been doing a lot of work in this area. You have to be clear whether you are interested in puberty (sexual maturation) or adolescence. We have looked at vaginal opening in females and preputial separation in males and found that this occurs around day 30. Adolescence has been defined as that continued maturation of the brain and behavior. In rats, days 35 to 55 is a good range although we have used days 40 to 50. I hope that this helps.

Thank you for responding. I'd like to do behavioral tests (anxiety, depression and memory) in male rats at puberty. However, I find no references that tell me for sure on which day these animals are considered pubescent, on scale of neurodevelopment.

Age at puberty varies with the strain of rat and the usually varied management in various labs. average of 76.5 with range of 53-142 days.

Please refer to article attached for more insight.

See S. R. OJEDA, J. E. WHEATON, H. E. JAMESON and S. M. McCANN (1976) The Onset of Puberty in the Female Rat: Changes in Plasma Prolactin, Gonadotropins, Luteinizing Hormone-Releasing Hormone (LHRH), and Hypothalamic LHRH Content, Endocrinology, 630-630, doi: 10.1210/endo-98-3-630

We have been doing a lot of work in this area. You have to be clear whether you are interested in puberty (sexual maturation) or adolescence. We have looked at vaginal opening in females and preputial separation in males and found that this occurs around day 30. Adolescence has been defined as that continued maturation of the brain and behavior. In rats, days 35 to 55 is a good range although we have used days 40 to 50. I hope that this helps.

You may want to read, "Development of skilled walking in the rat" it is a rat development paper and outlines the various stages in rat development from birth to adolescence (P0-P30). I hope that is helpful. P90 is generally considered adulthood.

http://www.ncbi.nlm.nih.gov/pubmed/19660502

Thank you, everyone! Suggestions were very helpful!

Days P40 to P60 can considered,  howeve,  we have used day P40 to day P45 as juvenile age in rats. 

Please refer to our following article for your answer:

https://www.researchgate.net/publication/255716093_The_Laboratory_Rat_Relating_Its_Age_With_Human%27s?_iepl%5BviewId%5D=pBGi1ncvbtzx4EVUsorucGO0&_iepl%5BprofilePublicationItemVariant%5D=default&_iepl%5Bcontexts%5D%5B0%5D=prfpi&_iepl%5BinteractionType%5D=publicationTitle

We are also having same solutions for mice model! 

Article The Laboratory Rat: Relating Its Age With Human's

I am late to the party on this question, but I found this article to be very helpful in considering timing of experiments in female rats relative to pubertal onset. It lays out all the milestones of female reproductive development in rats and how it compares to humans and other animals.

Refer to this paper: McCutheon & Marinelli, Age Matters.

Eur J Neurosci . 2009 March ; 29(5): 997–1014. doi:10.1111/j.1460-9568.2009.06648.x.

According to PMID23930179, although rats become sexually mature at age 6-7 weeks (which is equivalent to the begging of puberty), social maturity is reached at approximately 5-6 months (which is equivalent to the beginning of human adulthood ~18 years). Reproductive senescence in female rats occurs between 15 and 20 months, while women enter menopause between 48 and 55 years. Therefore, most reports have addressed the term "aged" to rats aged 20 months or older.