How does a newly born mouse get to the nipple? odor substrates eliciting first nipple grasping and sucking responses

Abstract

It is a mammalian female strategy to emit odor cues and signals that direct their inexperienced newborns to the nipple, and optimize their initial sucking success and, hence, viability. Here, natural odorous substrates that contribute to nipple grasping were investigated in mice, a species that has not been much scrutinized on this topic. The response of pups toward the nipples of lactating females (LF) versus nonlactating females (NLF) were first assessed right after watched birth, before and after the first suckling experience, and at 1 day old, after more extended suckling experience. It appeared that only nipples of LF induced grasping at these early ages, leading to take NLF as the baseline setting to present various odor substrates sampled from LF, viz. amniotic fluid, murine milk, LF saliva, pup saliva, LF urine, and an odorless control stimulus (water). Results indicate that: (1) only amniotic fluid and fresh milk induced nipple grasping before the first suckling experience; (2) LF saliva started inducing grasping after the first suckling experience; (3) pup saliva released grasping after 24-36 hr of suckling experience; finally (4) neither LF urine, nor water induced any nipple grasping. In conclusion, the activity of amniotic fluid and murine milk on neonatal pup behavior before any postnatal suckling experience suggests that either prenatal learning and/or predisposed olfactory mechanisms do operate, while the behavioral activation due to maternal and infantile salivas clearly depends on postnatal exposure.

Initiation and developmental dynamics of Wfs1 expression in the context of neural differentiation and ER stress in mouse forebrain

“…Wfs1 expression was notably upregulated in the layer V of Cg, RS, and M. Cg and RS cortices regulate the olfactory system, which starts functioning just immediately after birth (Treloar et al, 2010). Cooperation of the olfactory system and motor functions is required for body movements and suckling, which are crucial for the survival of a newborn pup (Al Aïn et al, 2013). The transient expression of Wfs1 in the layer V of all neocortical regions (also showed by Kawano et al, 2009), and in the subplate/layer VIb neurons suggests a role during corticogenesis.…”

Neurobehavioral assessment of maternal odor in developing rat pups: implications for social buffering

“…Rather, human and animal research suggests that the maternal odor is learned repeatedly, beginning in utero and throughout early life, presumably to support learning of the amniotic fluid odors and the mother’s diet-dependent odor (Al Aïn, Belin, Schaal, & Patris, 2013; Blass, 1990; Brake, 1981; Cheslock, Varlinskaya, Petrov, & Spear, 2000; Fillion & Blass, 1986; Hofer et al, 1976; Johanson & Teicher, 1980; Mainardi, Marsan, & Pasquali, 1965; Pedersen & Blass, 1982; Raineki et al, 2010, 2010; Ronca & Alberts, 1994; Sullivan & Leon, 1986; Sullivan, Perry, Sloan, Kleinhaus, & Burtchen, 2011; Sullivan et al, 1990; Teicher & Blass, 1977). The infant is also able to quickly learn new olfactory signature of the mother, which acquires the power of eliciting/controlling the baby–mother interactions (Marlier et al, 1998; Schleidt & Genzel, 1990; Sullivan et al, 1991; Sullivan & Toubas, 1998).…”

Odor‐induced crawling locomotion in the newborn rat: Effects of amniotic fluid and milk

“…However, research suggests that AF also plays an important role in the behavioral development of the fetus. For example, in rat fetuses AF plays a role in modulating fetal responses to chemosensory stimulation (Korthank & Robinson, ), in establishing odor preferences that will help direct the newborn to the nipple (Al Aïn, Belin, Schaal, & Patris, ; Kodama, ; Pedersen & Blass, ), and in shaping later dietary preferences (Smotherman, ). In humans, AF appears to prepare the fetus for the transition to birth and postnatal life (Porter, Winberg, & Varendi, ; Schaal, ).…”