Induction of maternal behavior in virgin rats after intracerebroventricular administration of oxytocin

Abstract

Oxytocin produces uterine contractions and milk ejection, functions related to parturition and nurturing. Studies were conducted to determine if this peptide, native to the brain and the posterior pituitary gland, plays a role in the induction of maternal behavior. Intact virgin female rats were given 0.4 ,g of oxytocin, 0.4 1&g of [Arg8Jvasopressin, or saline through lateral ventricular cannulae. Forty-two percent of intact rats receiving oxytocin displayed full maternal behavior towards foster pu s. None of the saline-or vasopressin-treated animals displayed full maternal behavior. Criteria in five behavioral categories had to be fulfilled by an animal within 2 hr of injection for its behavior to be considered fully maternal. When partial maternal responses were considered, oxytocin was significantly more effective than saline and marginally more effective than vasopressin. Five animals responding fully maternally after oxytocin injection were allowed to stay with pups for 10 days. All Rosenblatt (1) demonstrated that male and female rats, including intact virgin females, manifest maternal behavior after contact with foster pups for 5-7 days. Since then, several attempts have been made to shorten the latency for this phenomenon by manipulations of estrogen, progesterone, or prolactin. When these hormones were administered on selected schedules to ovariectomized, nulliparous females over either an 1 -day (2) or 27-day (3) period, latency was reduced to as little as 35 hr.Pharmacologic blockade of prolactin release has no effect on the onset of postpartum maternal behavior (3-5) or estrogen-induced maternal behavior (6). Similarly, induced elevation of prolactin in ovariectomized virgin females does not alter the onset of pup contact-induced maternal behavior (7). Progesterone has been found by most investigators to inhibit the onset of maternal behavior under various experimental conditions (8, 9), though dosage and timing of progesterone administration seem to be important (10).Of the hormones studied singly, estrogen appears most potent in inducing maternal behavior. Hysterectomy in late pregnancy, which probably causes a rapid rise in plasma estrogen (11) as judged by examination of vaginal smears, results in a high incidence of maternal behavior 48-72 hr after pup contactThe publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact. 6661 initiated 48 hr after surgery (12-14). Ovariectomy simultaneous with hysterectomy prevents this effect. The estrogen dependence of the induction of maternal behavior is further shown by estradiol administration at the time of hysterectomy and ovariectomy in either late gestational or virginal female rats. Animals thus treated show a high rate of maternal response within 24 hr after first presentation of pups 48 hr after surgery (12,15,16).Klopfer is the only investigator who has not focused exclusively on late gestati...

The neurobiology of social attachment: A comparative approach to behavioral, neuroanatomical, and neurochemical studies

“…Finally, OT and AVP were known to be important for the bond between mother and offspring. Indeed, central administration of OT has been found to enhance maternal behavior in sheep (Kendrick et al, 1987) and rats (Pederson et al, 1979).…”

“…This pairing of sex with peptide was probably chosen because of the known sexual dimorphism and testosterone sensitivity of the BNST-LS AVP pathway and involvement of OT in mother-infant bonding (Pederson et al, 1979;De Vries et al, 1983;Kendrick et al, 1987;De Vries et al, 1990;Kendrick et al, 1992). Thus, AVP and OT were thought to have gender specific effects; AVP regulating pair bonding in male prairie voles and OT regulating the same behavior in female prairie voles Williams et al, 1994;Insel et al, 1995a).…”

Neural circuits underlying crying and cry responding in mammals

“…A review of some of the evidence for neurochemical control of vocalizations in anxiety-provoking circumstances has been presented by Newman [72]. In addition, the neuropeptides vasopressin (AVP) and oxytocin (OT) have attracted a lot of interest, due to the evidence that they are involved in regulating social attachment behavior in rodents and non-human primates [39,41,42,49,70,92,120,121].…”

“…Saline-or vasopressin-treated animals showed no maternal behavior. The oxytocin-induced maternal behavior was facilitated by concomitant administration of estradiol benzoate, to simulate the hormonal status of females in estrus [92]. Oxytocin in the nucleus accumbens has been associated with parental vigor in caring for pups in the prairie vole [85].…”

Can Understanding Social Preferences in Rodents Lead to Novel Pharmacotherapies for Social Anxiety and Avoidance in Psychiatric Disorders?

“…The first evidence that oxytocin influences behavior came in the 1980s, when Cort Pedersen and colleagues reported that oxytocin induces the onset of maternal behavior in virgin rats (Pedersen and Prange, 1979), and Kendrick et al (1997) showed that oxytocin stimulates the mother-infant bond in sheep. A series of papers published in the 1990s using monogamous prairie voles as subjects showed that oxytocin also stimulates pair bonding (reviewed in Ross and Young, 2009).…”