Evidence map›Paper›PMID 41874612›Full record

ArticlePsychopharmacology2026

High incidence of estrous cycle irregularities in heterogeneous stock (HS) rats is associated with footshock-resistant cocaine intake.

Elizabeth A Sneddon, Supakorn Chonwattanagul, Kathleen Bai, Pranav H Kurup, Sonja L Plasil, Michelle R Doyle, Sélène Zahedi, Sierra Simpson, Benjamin C Sichel, Dyar N Othman and 6 more

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Psychopharmacology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Vaginal cytology in the queen: clinical and cytological correlations.Journal of feline medicine and surgery · 2026
    Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

16 authors.

Elizabeth A SneddonDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Supakorn ChonwattanagulDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Kathleen BaiDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Pranav H KurupDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Sonja L PlasilDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Michelle R DoyleDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Sélène ZahediDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Sierra SimpsonDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Benjamin C SichelDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Dyar N OthmanDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Molly BrennanDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Abraham A PalmerDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Marsida KallupiDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Lieselot L G CarretteDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Giordano de GuglielmoDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA.
Olivier GeorgeDepartment of Psychiatry, University of California San Diego, 9500 Gilman Dr. MC 0714, La Jolla, CA, 92093-0737, USA. olgeorge@health.ucsd.edu.

Funding

Sequencing CoreP50DA037844 · NIDA · UNIVERSITY OF CHICAGO · PI PALMER, ABRAHAM A · 2014 to 2023
$27.4M
Identification of Genetic Variants that Contribute to Compulsive Cocaine Intakein RatsU01DA043799 · NIDA · UNIVERSITY OF CALIFORNIA, SAN DIEGO · PI Olivier George, Abraham A Palmer · 2017 to 2026
$7.9M
Use of Next-Gen Sequencing to Identify Genetic Variants that Influence compulsiveOxycodone Intake in Outbred RatsU01DA044451 · NIDA · UNIVERSITY OF CALIFORNIA, SAN DIEGO · PI Olivier George, Abraham A Palmer · 2018 to 2026
$7.3M
DP30DA060810 · NIDA · UNIVERSITY OF CALIFORNIA, SAN DIEGO · PI Abraham A Palmer · 2024 to 2026
$5.6M
Investigation of how sex steroids and nicotinic acetylcholine receptors promote cocaine self-administration K00DA057923 · NIDA · UNIVERSITY OF CALIFORNIA, SAN DIEGO · PI Elizabeth Sneddon · 2023 to 2026
$344k
NIDA NIH HHS K00 DA057923NIDA NIH HHS K00DA057923NIDA NIH HHS P30 DA060810NIDA NIH HHS P50 DA037844NIDA NIH HHS P50DA037844NIDA NIH HHS U01DA04379NIDA NIH HHS U01 DA043799NIDA NIH HHS U01 DA044451
6 · The paper itself

Abstract

rationaleHormonal fluctuations throughout the estrous cycle are hypothesized to influence drug-related behaviors. Preclinical models show that some cocaine-related behaviors are influenced by the estrous cycle. However, the extent to which the estrous cycle modulates cocaine self-administration in outbred heterogeneous stock (HS) rats is unknown.

objectivesWe aimed to examine the relationship between estrous phases and cocaine self-administration behavior in HS rats using an operant model of extended access to cocaine self-administration.

methodsWe assessed the escalation of intake, breaking point, and resistance to foot shock. Using vaginal swabbing and lavage techniques, we characterized the relationship between estrous phase and cocaine behaviors. We then comprehensively evaluated estrous cycling patterns in young adult and adult HS rats, comparing them with Wistar rats.

resultsEstrous phase showed no association with cocaine self-administration in HS rats. 82% of female HS rats exhibited irregular estrous cycling with variability to the phase length, even in the absence of drug exposure, a phenomenon not observed in the Wistar strain. Females with irregular cycling showed greater footshock-resistant cocaine intake.

conclusionsThis study provides the first evidence that most female HS rats exhibit irregular estrous cycling. In HS rats, the estrous phase per se has no major influence on cocaine self-administration, whereas cycling irregularity was associated with specific addiction-related behaviors, including footshock-resistant intake. As HS rats gain popularity in behavioral and genome-wide studies, understanding these cycle disruptions is crucial as they may reveal genetic links into cycling variability and individual differences to aspects of cocaine use.

Indexed as

CocaineEstrous cycleFemalesHeterogenous Stock ratsHormonal fluctuationsOperant self-administrationWistar rats

Identifiers

PMID41874612
PMCPMC13170775

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.