Infant-mother interactions of oxytocin knock-out (OTKO) pups. Ten day old pups were place in one chamber of a testing arena in which the mother was restricted to a second chamber. The divider contained small holes that were large enough for the pup to pass through, but that prevented the mother from entering. The latency for the pup to enter the mother's chamber was recorded on three successive trials. There was no difference between wildtype and OTKO pups in the initial training trial. However, in the subsequent trials OTKO pups exhibited a significantly longer latency than wild-type pups to cross into the mother's chamber (p
Figure 3
Species differences in oxytocin receptor…
Figure 3
Species differences in oxytocin receptor (OTR) expression in prairie and montane voles. Notice…
Figure 3 Species differences in oxytocin receptor (OTR) expression in prairie and montane voles. Notice the higher level of OTR binding in the caudate (CP) and nucleus accumbens (NAcc) of the prairie vole (A) than the montane vole (B). Both species have OTR binding in the prefrontal cortex (PFC) C) Graph illustrating the effects of administering oxytocin antagonist (OTA) or cerebral spinal fluid (CSF) into the PFC, CP, or NAcc on pair bonding behavior in female prairie voles. Administering OTA into the CP or CSF during a 24-hour cohabitation with mating, does not effect the formation of a partner preference. However, injecting OTA into the PFC or NAcc blocked females from bonding with their mating partner, showing that oxytocin in these areas is important for affiliative behavior in a monogamous vole. Adapted from [55, 58] with permission.
Figure 4
Viral vector mediated over-expression of…
Figure 4
Viral vector mediated over-expression of oxytocin receptor (OTR) in the nucleus accumbens (NAcc)…
Figure 4 Viral vector mediated over-expression of oxytocin receptor (OTR) in the nucleus accumbens (NAcc) of female prairie voles enhances partner preference formation. Shown is the OTR binding density in female prairie voles receiving bilateral injection into the NAcc of an adeno-associated viral vector expressing green fluorescent protein (GFP) (A) or the prairie vole OTR gene. C) After a cumulative 18 h cohabitation with a male partner, females over-expressing OTR in the NAcc spent significantly more time with the partner, than the stranger, during a partner preference test (p
Figure 5
Light micrograph of oxytocin-immunoreactive fibers…
Figure 5
Light micrograph of oxytocin-immunoreactive fibers in the prairie vole from a horizontal section.…
Figure 5 Light micrograph of oxytocin-immunoreactive fibers in the prairie vole from a horizontal section. Notice that a few fibers deviate from the neurohypophysial pathway of the paraventricular nucleus of the hypothalamus (PVN) and project toward the nucleus accumbens (NAcc). Scale bar = 100 μm. ac = anterior commisure, f = fornix. Reprinted from [59] with permission.
Figure 6
Oxytocin receptor binding (A-C) and…
Figure 6
Oxytocin receptor binding (A-C) and oxytocin-immunoreactive fiber distribution (D-F) in rats (top), mice…
Figure 6 Oxytocin receptor binding (A-C) and oxytocin-immunoreactive fiber distribution (D-F) in rats (top), mice (middle) and prairie voles (bottom). Note the remarkable species differences in oxytocin receptor binding in the nucleus accumbens (NAcc), but similarity in oxytocin-immunoreactive fibers. ac = anterior commisure. Adapted from [1, 59] with permission.
Figure 7
Models of the possible origin…
Figure 7
Models of the possible origin of the oxytocin (OT)-immunoreactive processes in NAcc. A)…
Figure 7 Models of the possible origin of the oxytocin (OT)-immunoreactive processes in NAcc. A) Separate neuronal populations comprise the neurohyphyseal OT system and the centrally projecting system. Magnocellular (mag) neurons project to the posterior pituitary while parvocellular (pv) neurons project to specific brain regions. This is the prevailing view of many investigators. B) Somatodendritically released OT from magnocellular hypothalamic neurons diffuses to distant brain regions in a paracrine fashion. C) Centrally projecting OT fibers may be axon collaterals of neurohyphyseal OT neurons that are projecting towards the pituitary. From our research in prairie voles, this model is most likely. Note that in models A and C, OT may influence OT receptor populations by either direct release from local processes, or after diffusion following somatodendritic release within the hypothalamus.
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