Elucidating potential neural correlates for positive affect induced by tickling in female and male juvenile Wistar rats.

Emma Tivey, Sarah Brown, Vincent Bombail, Birte L. Nielsen, A B Lawrence, Simone Meddle

Research output: Contribution to conferenceAbstractpeer-review

Abstract

Positive welfare is considered to be not simply the absence of suffering but also the presence of positive experiences. ‘Tickling’ has been shown to induce positive affective states in laboratory rats as evidenced by the production of 50 kHz ultrasonic vocalisations (USVs). Tickling studies have shown inconsistent results of the response to tickling between male and female rats and few studies have investigated positive affect in female rats alone. Therefore, whether female and male rats respond differently to being tickled and the positive affect induced by tickling is not well understood. It was hypothesised that female rats exhibit different behavioural responses and neural correlates to tickling than male rats due to sex-specific neural regulation of positive affective states. Rats (n=32/sex) received either tickling (Tickled, n=16/sex) or no hand contact (Controls, n=16/sex). Play behaviours and USVs were quantified. Rats were culled and their brains taken: double-labelled immunohistochemistry was used to quantify c-fos expression (a marker of neuronal activity) in oxytocinergic neurons of the paraventricular nucleus of the hypothalamus (PVN); these neurons project to the reward circuitry and are thought to play a vital role in coding the rewarding nature of prosocial behaviours. We found that tickled female rats produced significantly more 50 kHz USVs than any tickled male or control rats (p<0.001) but the number of trill 50 kHz USVs (associated with reward and positive affect) did not differ significantly between tickled females and tickled males (p= 0.133). Tickled rats had significantly more active magnocellular (p=0.006) and parvocellular (p=0.014) oxytocin neurons in the PVN and this was independent of sex. This suggests a role of the oxytocin system in aspects of positive affect, which may not differ between male and female rats. Elucidating the neurobiological basis of positive affect will develop our understanding of the importance of positive welfare.
Original languageEnglish
Publication statusPublished - 2020
EventAssociation for the Study of Animal Behaviour (ASAB) Virtual Winter Meeting -
Duration: 3 Dec 20204 Dec 2020

Conference

ConferenceAssociation for the Study of Animal Behaviour (ASAB) Virtual Winter Meeting
Period3/12/204/12/20

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