Individual Differences in Autonomic Responsivity in the Adult Rat

Abstract

Compared with undisturbed controls, rats handled on Days 1-7 of life exhibited diminished cardiac response to handling and to novel stimulation at 100 days of age. Previous handling had a greater effect in females. Defecation scores were significantly reduced by prior handling, although correlation between measures of heart rate and defecation frequency was not significant. Between the groups, behavioral measures did not appear to be responsible for differences in heart rate. In adulthood, females had higher heart rates after handling than did males; these differences reflected differences in reactivity, as there were no differences in heart rate between sexes after they had adapted to the test situation. Heart rate correlated negatively with body weight across both sexes. Within-sex correlations of heart rate and body weight were also negative but generally not significant. If confirmed, the data indicate an effect of experimental factors on heartrate reactivity which may have important clinical implications.

Influence of neonatal handling on blood pressure, locomotor activity, and preweanling heart rate in spontaneously hypertensive and Wistar Kyoto rats

“…Sex differences in cardiovascular responses to manipulation of early experience and to subsequent stressors also modulate the influence of environmental conditions on regulatory functioning. For example, Blizard (1971) observed that, among rats handled daily prior to weaning (at 21 days), attenuation of the expected tachycardia during openfield testing was greater in females than in males. Henry, Meehan, and Stephens (1967) reported that, when subjected to chronic psychosocial stress, male mice of the CBA strain developed sustained hypertension, while the blood pressures of females remained within the normal range.…”

“…TUCKER AND JOHNSON tally shaped aspects of the cardiovascular and behavioral reactivity observed among SHR rats. For this purpose, a neonatal handling procedure, previously shown to attenuate the behavioral and physiological reactivity of rodents to a variety of environmental conditions (e.g., Ader, 1975;Blizard, 1971;Denenberg & Zarrow, 1971;Levine, Haltmeyer, Karas, & Denenberg, 1967;Levine & Mullins, 1966;Whimbey & Denenberg, l966,1967a, b ), was used to modify response patterns subject to alteration by early experience. This design allowed critical examination of the hypothesized, but as yet unproven (Tucker & Johnson, 1 98l), association between behavioral and cardiovascular hyperresponsiveness within the SHR strain.…”

Influence of postnatal maternal stress on blood pressure and heart rate of juvenile and adult rat offspring

“…Withal, there is scant evidence for an influence on cardiovascular function: adult rats handled as neonates are reported to have a reduced heart rate response to novel stimulation (Blizard, 1971). Suggestive of a maternal influence, correlation analysis indicates that differences in behavioral interactions between rat mothers and pups contribute to variance in adult blood pressure (Myers et al, 1989).…”

Altered Development of the Rat Brain Serotonergic System after Disruptive Neonatal Experience

“…These "disruptive early experiences," such as exposure to temperature extremes or electric shocks, have been reported to alter adult behaviors, including open-field activity, active-avoidance, startle' responses, and "emotionality"' (6)(7)(8). Disruptive early experience also affects several neuroendocrine -parameters that involve the hypothalamic-pituitary-adrenal response to stress (5,9,10 (12)(13)(14). Con of mean) between groups of rats given cold treatment on postnatal day 1 (0) and untreated controls (-) when tested for three consecutive days as adults at about 240 days of age.…”

“…One important aspect of disruptive experience is that it must occur early in life in order to have profound consequences (6). We tested this notion of a "critical period" by administering cold treatment on either postnatal day 6 or day 10. Treatment on day 6 brought about elevations in 5HT levels in the fore-and midbrain in both sexes on day 17, as shown in Fig.…”