The hormonal basis for parental care in rattlesnakes

Pigmy Rattlesnakes, Sistrurus miliarius.

Rattlesnakes have been documented to show parental care, a complex social behavior that is widespread among vertebrates. This behavior has been linked to neuroendocrine regulation in mammals, and, to a lesser extent, birds and fish. However, its influence on reptiles is poorly known. In mammalian species and humans, the posterior pituitary hormones in the  oxytocin and vasopressin families mediate parental care behaviors. In a forthcoming paper in Biology Open, Lind et al. (2017) test the hypothesis that the regulatory role of posterior pituitary neuropeptides is conserved in a viviparous squamate reptile. The researchers pharmacologically blocked the vasotocin receptor in postparturient Pigmy Rattlesnakes, Sistrurus miliarius, and monitored the spatial relationship between females and their offspring relative to controls. Mothers in the control group demonstrated spatial aggregation with offspring, with mothers having greater postparturient energy stores aggregating more closely with their offspring. Blockade of vasotocin receptors eliminated evidence of spatial aggregation between mothers and offspring and eliminated the relationship between maternal energetic status and spatial aggregation. The results are the first to implicate posterior pituitary neuropeptides in the regulation of maternal behavior in a squamate reptile and are consistent with the hypothesis that the neuroendocrine mechanisms underlying social behaviors are broadly conserved among vertebrates.

Lind CM, Birky NK, Porth AM, Farrell TM. Vasotocin receptor blockade disrupts maternal care of offspring in a viviparous snake, Sistrurus miliarius. Biology Open. 2017 Jan 1:bio-022616.

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