Dopaminergic D2-like agonists produce yawning in the myelin mutant taiep and Sprague–Dawley rats

Central administration of oxytocin differentially increases yawning, penile erections and scratching in high- (HY) and low-yawning (LY) sublines of Sprague–Dawley rats

“…The yawn ended when rats closed their mouth and returned to normal breathing (Holmgren et al, 1985;Eguibar et al, 2012). Penile erection consisted of pelvic thrusts immediately followed by the rat sitting in an upright position, an engorged penis, and subsequently the animal licking the perigenital area and even ingesting the ejaculate (Bagdy and Makara, 1995).…”

Yawning and Penile Erection Frequencies Are Resilient to Maternal Care Manipulation in the High-Yawning Subline of Sprague–Dawley Rats

“…On the other hand, HY male rats allow us to show that this innate behavioral pattern is strongly correlated with spontaneous penile erections in a very short time window of only 3 min; in fact, 50% of yawns and penile erections happen together (Holmgren et al, 1985). Yawning frequency also correlated with the number of penile erections after systemic administration of D 2 -like dopaminergic agonists such as apomorphine in low doses, bromocriptine, or (−)-quinpirole (Urbá-Holmgren et al, 1993;Eguibar et al, 2003); this behavioral correlation is present even in a myelin mutant rat with progressive demyelination (Eguibar et al, 2012).…”

“…Yawning was characterized as a prolonged (∼1 s) wide opening of the mouth accompanied by deep inspiration and sometimes associated with tongue protrusion (Ushijima et al, 1984). The yawn ended when rats closed their mouths and returned to normal breathing (Holmgren et al, 1985;Eguibar et al, 2012Eguibar et al, , 2015. Penile erection FIGURE 1 | Experimental design.…”