Neonatal pain and stress disrupts later-life pavlovian fear conditioning and sensory function in rats: Evidence for a two-hit model

A Double Hit of Social and Economic Stress in Mice Precipitates Changes in Decision-Making Strategies

BACKGROUND

Economic stress can serve as a second hit for people who have already accumulated a history of adverse life experiences. How one recovers from a setback is a core feature of resilience but is seldom captured in animal studies.

METHODS

We challenged mice in a novel 2-hit stress model by first exposing them to chronic social defeat stress and then testing adaptations to increasing reward scarcity on a neuroeconomic task. Mice were tested across months on the Restaurant Row task, during which they foraged daily for their primary source of food while on a limited time budget in a closed-economy system. An abrupt transition into a reward-scarce environment elicits an economic challenge, precipitating a drop in food intake and body weight to which mice must respond to survive.

RESULTS

We found that mice with a history of social stress mounted a robust behavioral response to this economic challenge that was achieved through a complex redistribution of time allocation among competing opportunities. Interestingly, we found that mice with a history of social defeat displayed changes in the development of decision-making policies during the recovery process that are important not only for ensuring food security necessary for survival but also prioritizing subjective value and that these changes emerged only for certain types of choices.

CONCLUSIONS

These findings indicate that an individual's capacity to recover from economic challenges depends on that person's prior history of stress and can affect multiple decision-making aspects of subjective well-being, thus highlighting a motivational balance that may be altered in stress-related disorders such as depression.

Impact of neonatal pain and opiate administration in animal models: A meta-analysis concerning pain threshold

BACKGROUND AND AIM

Neonatal intensive care treatment, including frequently performed painful procedures and administration of analgesic drugs, can have different effects on the neurodevelopment. This systematic review and meta-analysis aimed to investigate the influence of pain, opiate administration, and pre-emptive opiate administration on pain threshold in animal studies in rodents, which had a brain development corresponding to preterm and term infants.

METHODS

A systematic literature search of electronic data bases including CENTRAL (OVID), CINAHL (EBSCO), Embase.com, Medline (OVID), Web of Science, and PsycInfo (OVID) was conducted. A total of 42 studies examining the effect of pain (n = 38), opiate administration (n = 9), and opiate administration prior to a painful event (n = 5) in rodents were included in this analysis.

RESULTS

The results revealed that pain (g = 0.42, 95%CI 0.16-0.67, p = 0.001) increased pain threshold leading to hypoalgesia. Pre-emptive opiate administration had the opposite effect, lowering pain threshold, when compared to pain without prior treatment (g = -1.79, 95%CI -2.71-0.86, p = 0.0001). Differences were found in the meta regression for type of stimulus (thermal: g = 0.66, 95%CI 0.26-1.07, p = 0.001; vs. mechanical: g = 0.13, 95%CI -0.98-1.25, p = 0.81) and gestational age (b = -1.85, SE = 0.82, p = 0.027). In addition, meta regression indicated an association between higher pain thresholds and the amount of cumulative pain events (b = 0.06, SE = 0.03, p = 0.05) as well as severity of pain events (b = 0.94, SE = 0.28, p = 0.001).

CONCLUSION

Neonatal exposure to pain results in higher pain thresholds. However, caution is warranted in extrapolating these findings directly to premature infants. Further research is warranted to validate similar effects in clinical contexts and inform evidence-based practices in neonatal care.

Repetitive neonatal procedural pain affects stress-induced plasma corticosterone increase in young adult females but not in male rats

Exposure to repetitive painful procedures in the neonatal intensive care unit results in long-lasting effects, especially visible after a "second hit" in adulthood. As the nociceptive system and the hypothalamic-pituitary-adrenal (HPA) axis interact and are vulnerable in early life, repetitive painful procedures in neonates may affect later-life HPA axis reactivity. The first aim of the present study was to investigate the effects of repetitive neonatal procedural pain on plasma corticosterone levels after mild acute stress (MAS) in young adult rats. Second, the study examined if MAS acts as a "second hit" and affects mechanical sensitivity. Fifty-two rats were either needle pricked four times a day, disturbed, or left undisturbed during the first neonatal week. At 8 weeks, the animals were subjected to MAS, and plasma was collected before (t0), after MAS (t20), and at recovery (t60). Corticosterone levels were analyzed using an enzyme-linked immunosorbent assay, and mechanical sensitivity was assessed with von Frey filaments. Results demonstrate that repetitive neonatal procedural pain reduces stress-induced plasma corticosterone increase after MAS only in young adult females and not in males. Furthermore, MAS does not affect mechanical sensitivity in young adult rats. Altogether, the results suggest an age- and sex-dependent effect of repetitive neonatal procedural pain on HPA axis reprogramming.

Effects of different types of neonatal pain on somatosensory and cognitive development in male juvenile rats

BACKGROUND

Premature infants are inevitably exposed to painful events, including repetitive procedures, inflammation, or mixed stimulation that may induce long-term behavioral outcomes. Here, we set up three neonatal painful models to investigate their long-term effect on somatosensation and cognition.

METHODS

Three types of neonatal pain models in rat were set up. Rat pups were randomly assigned to four groups. The needling pain (NP) group received repetitive needle pricks on the paws from the day of birth (PD0) to postnatal day 7 (PD7) to mimic the diagnostic and therapeutic procedures. The inflammatory pain (IP) group received the injection of carrageenan into the left hindpaw at PD3 to induce IP in peripheral tissues. The mixed pain group received a combination of the NP and IP (NIP). The control (CON) group was untreated. We performed behavioral and biochemical testing of juvenile rats (PD21-PD26).

RESULTS

The NIP group showed a longer hypersensitivity than the NP group, when given a secondary inflammatory stimulation. NP led to insensitivity to anxiety-causing stimuli and impairment of fear memory both aggravated by NIP. NP reduced the expression of synapse-related molecules (GluN1/PSD95/GFAP) in the medial prefrontal cortex, and NIP exacerbated this decrease. The corticosterone secretion in the NIP group increased after the behavioral task, compared with those in other three groups.

CONCLUSION

A combination of NP with inflammation occurring in the neonatal period might aggravate the adverse effects of each on somatosensory and cognitive development of rats, the mechanism of which might be associated with the increase of corticosterone secretion and the dysregulation of synaptic molecules.

Infant pain vs. pain with parental suppression: Immediate and enduring impact on brain, pain and affect

BACKGROUND

In the short term, parental presence while a human infant is in pain buffers the immediate pain responses, although emerging evidence suggests repeated social buffering of pain may have untoward long-term effects.

METHODS/FINDING

To explore the short- and long-term impacts of social buffering of pain, we first measured the infant rat pup's [postnatal day (PN) 8, or 12] response to mild tail shock with the mother present compared to shock alone or no shock. Shock with the mother reduced pain-related behavioral activation and USVs of pups at both ages and reduced Fos expression in the periaqueductal gray, hypothalamic paraventricular nucleus, and the amygdala at PN12 only. At PN12, shock with the mother compared to shock alone differentially regulated expression of several hundred genes related to G-protein-coupled receptors (GPCRs) and neural development, whereas PN8 pups showed a less robust and less coherent expression pattern. In a second set of experiments, pups were exposed to daily repeated Shock-mother pairings (or controls) at PN5-9 or PN10-14 (during and after pain sensitive period, respectively) and long-term outcome assessed in adults. Shock+mother pairing at PN5-9 reduced adult carrageenan-induced thermal hyperalgesia and reduced Fos expression, but PN10-14 pairings had minimal impact. The effect of infant treatment on adult affective behavior showed a complex treatment by age dependent effect. Adult social behavior was decreased following Shock+mother pairings at both PN5-9 and PN10-14, whereas shock alone had no effect. Adult fear responses to a predator odor were decreased only by PN10-14 treatment and the infant Shock alone and Shock+mother did not differ.

CONCLUSIONS/SIGNIFICANCE

Overall, integrating these results into our understanding of long-term programming by repeated infant pain experiences, the data suggest that pain experienced within a social context impacts infant neurobehavioral responses and initiates an altered developmental trajectory of pain and affect processing that diverges from experiencing pain alone.

Repeated neonatal Needle-pricking stimulation alter neurodevelopment in adolescent rats

OBJECTIVE

To explore the repeated pain stimulation in neonatal rats affects their cognitive and memory abilities during puberty, and the proliferation expression of hippocampal neurons.

METHODS

Postnatal 1 day (P1) SD rats were randomly divided into two groups, and the skin of the needle group was pricked for seven days consecutively while the skin of the control group was stroked for the same period of time. The rats in both groups were weighed every week, and the Morris water maze experiment was performed from P44 to P49 to test the cognitive and memory abilities of the rats. On P50, the hippocampal tissue was extracted for observation of pathological features and the expressions of Ki-67 and caspase 3 were determined.

RESULTS

With the increase of the days, the body weight of the rats in the needle group increased slightly slower than that of the control group. The escape latency of the needle group was significantly higher than that of the control group in the water maze test at P45 and P48, and the number of times the rats crossing the platform in the needle group was lower than that of the control group. The HE staining of the hippocampal tissue showed that the cells in the needle group were disorganized, with irregular morphology. Under the electron microscope, the structure of neuron cells and organelles is changed in the hippocampal CA1 region of rats. It showed a decrease in the Ki-67 expression and an increase in caspase 3 in the needle group.

CONCLUSION

Repeated experience of needle-pricking stimulation in neonatal rats can cause cognitive impairment and memory loss in puberty, disrupt hippocampal organization, and diminish neuronal proliferation.

A high-fat high-sugar diet and adversity early in life modulate pain outcomes at the behavioural and molecular level in adolescent rats: The role of sex

Given that adolescence is a significant period of brain plasticity and development, early life factors have the potential to alter long term outcomes. For instance, adversities such as consumption of a high-fat high-sugar (HFHS) diet and adverse childhood experiences (ACEs; e.g., neglect), and their resulting inflammation and microglial activation can influence pain outcomes by priming the neuroimmune system to overrespond to stressors. Chronic pain is highly prevalent amongst the adolescent population, with the prevalence and manifestation being sexually dimorphic. Although clinical studies show that females are twice as likely to report pain problems compared to males, the majority of pre-clinical work uses male rodents. Therefore, our aim was to examine the effects of sex, a HFHS diet, and an ACE on chronic pain outcomes following a stressor in adolescence. Rat dams were randomly assigned to a Standard or HFHS diet, with pups maintained on their respective diets then randomly allocated to a No Stress or ACE paradigm, and a Sham or Injury condition as a stressor. Results showed that early life adversities increased nociceptive sensitivity, inflammation, and microglial activation systemically and within the brain. Behaviourally, pain outcomes were more prominent in females, however the neuroimmune response was exacerbated in males. These results demonstrate the sexual dimorphism of chronic pain outcomes following early life adversities and provide insight into the mechanisms driving these changes, which will inform more targeted and effective treatment strategies for youth living with chronic pain.

Enriched environment rescues neonatal pain induced cognitive deficits and the impaired hippocampal synaptic plasticity later in life

Although extensive and untreated pain that occurs during a critical developmental window may impair cognition later in life, environmental interventions at early might promote. However, the underlying mechanism is poorly understood. Our current study utilized a rat model of "repetitive needle pricks" from the day of birth (P0) to postnatal day 7 (P7) to mimic the painful experience of preterm neonates in the Neonatal intensive care unit (NICU). Enriched environment (EE) during development period (from P15 to P70) was implemented as a nonpharmacological intervention approach. Electrophysiological recording, behavioral tests and biochemical analysis were performed after the end of EE (between P71 and P80). Results showed neonatal repetitive pain resulted in a reduction in mechanical withdrawal thresholds by the von Frey test in P70 (P < 0.001). Furthermore, neonatal repetitive pain impaired spatial learning and memory (P < 0.05) and even led to dysfunction in fear memory (P < 0.01). In contrast, EE rescued neonatal pain induced cognitive deficits and normalized hippocampal long-term potentiation in rats exposed to neonatal pain (P < 0.05). The beneficial effect of EE might be the improvements in hippocampal synaptic plasticity via up-regulating neurotrophic factors and N-methyl-D-aspartate (NMDA) receptors in the hippocampus. Our findings provide evidence that early environmental intervention might be a safe strategy to overcome neurodevelopmental abnormalities in preterm infants who experienced multiple procedural painful events during the early critical period. This article is protected by copyright. All rights reserved.

Early Life Painful Procedures: Long-Term Consequences and Implications for Farm Animal Welfare

Farm animals routinely undergo painful husbandry procedures early in life, including disbudding and castration in calves and goat kids, tail docking and castration in piglets and lambs, and beak trimming in chicks. In rodents, inflammatory events soon after birth, when physiological systems are developing and sensitive to perturbation, can profoundly alter phenotypic outcomes later in life. This review summarizes the current state of research on long-term phenotypic consequences of neonatal painful procedures in rodents and farm animals, and discusses the implications for farm animal welfare. Rodents exposed to early life inflammation show a hypo-/hyper-responsive profile to pain-, fear-, and anxiety-inducing stimuli, manifesting as an initial attenuation in responses that transitions into hyperresponsivity with increasing age or cumulative stress. Neonatal inflammation also predisposes rodents to cognitive, social, and reproductive deficits, and there is some evidence that adverse effects may be passed to offspring. The outcomes of neonatal inflammation are modulated by injury etiology, age at the time of injury and time of testing, sex, pain management, and rearing environment. Equivalent research examining long-term phenotypic consequences of early life painful procedures in farm animals is greatly lacking, despite obvious implications for welfare and performance. Improved understanding of how these procedures shape phenotypes will inform efforts to mitigate negative outcomes through reduction, replacement, and refinement of current practices.

Neonatal procedural pain affects state, but not trait anxiety behavior in adult rats

The influence of neonatal experiences upon later-life affective behavior is increasingly recognized, but the reported effects on anxiety are often contradictory. The observed effect may depend upon the type of anxiety (state or trait) affected. The current study aims to investigate whether neonatal repetitive needle pricking alters anxiety behavior in adulthood, by assessing both state and trait anxiety in rats. Sprague-Dawley rat pups received four unilateral needle pricks per day, while controls received four tactile stimuli or were left completely undisturbed during the first postnatal week. Mechanical sensitivity was assessed in the neonatal phase and throughout the development. State anxiety was assessed in the open field test and trait anxiety in the elevated zero maze. The results show that repetitive needle pricking leads to acute mechanical hypersensitivity, but does not affect baseline mechanical sensitivity throughout development. In adulthood, animals previously exposed to neonatal procedural pain (including repetitive handling and removal from litter) showed lower state anxiety but did not differ in trait anxiety, as compared with the undisturbed controls. These findings indicate that early-life procedural pain decreases state but not trait anxiety behavior in later life in a rodent model of repetitive needle pricking.

Maternal separation with neonatal pain influences later-life fear conditioning and somatosenation in male and female rats

Early life adversity, including that which occurs in a medical setting, has been increasingly shown to have lasting consequences on both physical and mental health. In order to understand the lasting effects of early-life adversity, such as that might occur in the neonatal intensive care unit (NICU), several rodent models have been developed including maternal separation, neonatal handling, and repeated needle prick pain. However, in the clinical scenario, these stressors are often combined. Thus, the current study seeks to observe the lasting impacts of both neonatal pain and maternal separation in a rodent model. Rats were separated from their dam for 6 h per day during the first 7 days of life, during which they were subjected to repeated needle prick pain or handling. A separate group was left undisturbed. All rats were subsequently tested for threat processing using a 3-day Pavlovian fear conditioning model and for somatosensation using measures of mechanical and thermal thresholds. Results indicated that rats subjected to maternal separation and pain had enhanced fear conditioning in adolescence as well as displaying a modest age-independent tactile hypersensitivity compared to undisturbed controls. These data show that experiencing combined neonatal pain and maternal separation may create a latent vulnerability to subsequent stressors.

Amygdalar Corticotropin-Releasing Factor Signaling Is Required for Later-Life Behavioral Dysfunction Following Neonatal Pain

Neonatal pain such as that experienced by infants in the neonatal intensive care unit is known to produce later-life dysfunction including heightened pain sensitivity and anxiety, although the mechanisms remain unclear. Both chronic pain and stress in adult organisms are known to influence the corticotropin-releasing factor (CRF) system in the Central Nucleus of the Amygdala, making this system a likely candidate for changes following neonatal trauma. To examine this, neonatal rats were subjected to daily pain, non-painful handling or left undisturbed for the first week of life. Beginning on postnatal day, 24 male and female rats were subjected to a 4-day fear conditioning and sensory testing protocol. Some subjects received intra-amygdalar administration of either Vehicle, the CRF receptor 1 (CRF₁) receptor antagonist Antalarmin, or the CRF receptor 2 (CRF₂) receptor antagonist Astressin 2B prior to fear conditioning and somatosensory testing, while others had tissue collected following fear conditioning and CRF expression in the CeA and BLA was assessed using fluorescent in situ hybridization. CRF₁ antagonism attenuated fear-induced hypersensitivity in neonatal pain and handled rats, while CRF₂ antagonism produced a general antinociception. In addition, neonatal pain and handling produced a lateralized sex-dependent decrease in CRF expression, with males showing a diminished number of CRF-expressing cells in the right CeA and females showing a similar reduction in the number of CRF-expressing cells in the left BLA compared to undisturbed controls. These data show that the amygdalar CRF system is a likely target for alleviating dysfunction produced by early life trauma and that this system continues to play a major role in the lasting effects of such trauma into the juvenile stage of development.

Repetitive Pain in Neonatal Male Rats Impairs Hippocampus-Dependent Fear Memory Later in Life

Preterm infants in neonatal intensive care units are inevitably subjected to numerous painful procedures. However, little is known about the consequences of early pain experience on fear memory formation later in life. We hypothesized that exposure to repetitive pain in early life triggered hippocampal synaptic plasticity and resulted in memory deficiency in prepubertal and adult rats. From the day of birth (P0) to postnatal day 7 (P7), neonatal male rat pups were randomly assigned to either needle pricks or tactile touches repetitively every 6 h. Trace fear conditioning was performed on rats on P24-P26 and P87-P89. On P24 and P87, rats were sacrificed for molecular and electrophysiological studies. On P24-26 and P87-89, rats that experienced neonatal needle treatment showed a significant reduction in freezing time in the contextual fear conditioning (P < 0.05) and trace fear conditioning tests (P < 0.05). Moreover, repetitive neonatal procedural pain caused a significant decrease in the magnitude of hippocampal long-term potentiation induced by high-frequency stimulation. Furthermore, rats that experienced neonatal needle treatment demonstrated sustained downregulation of NR1, NR2A, NR2B, and GluR1 expression in the hippocampus. Therefore, neonatal pain is related to deficits in hippocampus-related fear memory later in life and might be caused by impairments in hippocampal synaptic plasticity.

Early Neonatal Pain-A Review of Clinical and Experimental Implications on Painful Conditions Later in Life

Modern health care has brought our society innumerable benefits but has also introduced the experience of pain very early in life. For example, it is now routine care for newborns to receive various injections or have blood drawn within 24 h of life. For infants who are sick or premature, the pain experiences inherent in the required medical care are frequent and often severe, with neonates requiring intensive care admission encountering approximately fourteen painful procedures daily in the hospital. Given that much of the world has seen a steady increase in preterm births for the last several decades, an ever-growing number of babies experience multiple painful events before even leaving the hospital. These noxious events occur during a critical period of neurodevelopment when the nervous system is very vulnerable due to immaturity and neuroplasticity. Here, we provide a narrative review of the literature pertaining to the idea that early life pain has significant long-term effects on neurosensory, cognition, behavior, pain processing, and health outcomes that persist into childhood and even adulthood. We refer to clinical and pre-clinical studies investigating how early life pain impacts acute pain later in life, focusing on animal model correlates that have been used to better understand this relationship. Current knowledge around the proposed underlying mechanisms responsible for the long-lasting consequences of neonatal pain, its neurobiological and behavioral effects, and its influence on later pain states are discussed. We conclude by highlighting that another important consequence of early life pain may be the impact it has on later chronic pain states-an area of research that has received little attention.

The Effects of Acute Neonatal Pain on Expression of Corticotropin-Releasing Hormone and Juvenile Anxiety in a Rodent Model

Premature infants in the neonatal intensive care unit (NICU) may be subjected to numerous painful procedures without analgesics. One necessary, though acutely painful, procedure is the use of heel lances to monitor blood composition. The current study examined the acute effects of neonatal pain on maternal behavior as well as amygdalar and hypothalamic activation, and the long-term effects of neonatal pain on later-life anxiety-like behavior, using a rodent model. Neonatal manipulations consisted of either painful needle pricks or non-painful tactile stimulation in subjects’ left plantar paw surface which occurred four times daily during the first week of life [postnatal day (PND)1–PND7]. Additionally, maternal behaviors in manipulated litters were compared against undisturbed litters via scoring of videotaped interactions to examine the long-term effects of pain on dam-pup interactions. Select subjects underwent neonatal brain collection (PND6) and fluorescent in situ hybridization (FISH) for corticotropin-releasing hormone (CRH) and the immediate early gene c-fos. Other subjects were raised to juvenile age (PND24 and PND25) and underwent innate anxiety testing utilizing an elevated plus maze (EPM) protocol. FISH indicated that neonatal pain influenced amygdalar CRH and c-fos expression, predominately in males. No significant increase in c-fos or CRH expression was observed in the hypothalamus. Additionally, neonatal pain altered anxiety behaviors independent of sex, with neonatal pain subjects showing the highest frequency of exploratory behavior. Neonatal manipulations did not alter maternal behaviors. Overall, neonatal pain drives CRH expression and produces behavioral changes in anxiety that persist until the juvenile stage.

Inflammatory neonatal pain disrupts maternal behavior and subsequent fear conditioning in a rodent model

Infants spending extended time in the neonatal intensive care unit are at greater risk of developing a variety of mental health problems later in life, possibly due to exposure to painful/stressful events. We used a rodent model of inflammatory neonatal pain to explore effects on fear conditioning, somatosensory function and maternal behavior. Hindpaw injections of 2% λ-carrageenan on postnatal days 1 and 4 produced an attenuation in conditioned freezing during the postweaning period, similar to our previous work with acute pain, but did not cause lasting impacts on contextual freezing nor somatosensory function. Additionally, we assessed maternal behavior to observe dam-pup interactions during the neonatal period. Results showed dams of litters which experienced pain spent similar amounts of time with pups as undisturbed controls. However, the specific behaviors differed per condition. Dams of pain litters exhibited less time licking/grooming, but more time nursing than controls. These results suggest changes in maternal care following pain could be a contributing factor underlying the long-term effects of neonatal trauma. Furthermore, our laboratory has previously shown acute, but not inflammatory pain, disrupted conditioned freezing; the current experiment observed the long-term effects of neonatal inflammatory pain on conditioned fear using a weak conditioning protocol.

Development of Threat Expression Following Infant Maltreatment: Infant and Adult Enhancement but Adolescent Attenuation

Early life maltreatment by the caregiver constitutes a major risk factor for the development of later-life psychopathologies, including fear-related pathologies. Here, we used an animal model of early life maltreatment induced by the Scarcity-Adversity Model of low bedding (LB) where the mother is given insufficient bedding for nest building while rat pups were postnatal days (PN) 8-12. To assess effects of maltreatment on the expression of threat-elicited defensive behaviors, animals underwent odor-shock threat conditioning at three developmental stages: late infancy (PN18), adolescence (PN45) or adulthood (>PN75) and tested the next day with odor only presentations (cue test). Results showed that in typically developing rats, the response to threat increases with maturation, although experience with maltreatment in early infancy produced enhanced responding to threat in infancy and adulthood, but a decrease in maltreated adolescents. To better understand the unique features of this decreased threat responding in adolescence, c-Fos expression was assessed within the amygdala and ventromedial prefrontal cortex (vmPFC) associated with the cued expression of threat learning. Fos counts across amygdala subregions were lower in LB rats compared to controls, while enhanced c-Fos expression was observed in the vmPFC prelimbic cortex (PL). Correlational analysis between freezing behavior and Fos revealed freezing levels were correlated with CeA in controls, although more global correlations were detected in LB-reared rats, including the BA, LA, and CeA. Functional connectivity analysis between brain regions showed that LB reared rats exhibited more diffuse interconnectivity across amygdala subnuclei, compared the more heterogeneous patterns observed in controls. In addition, functional connectivity between the IL and LA switched from positive to negative in abused adolescents. Overall, these results suggest that in adolescence, the unique developmental decrease in fear expression following trauma is associated with distinct changes in regional function and long-range connectivity, reminiscent of pathological brain function. These results suggest that early life maltreatment from the caregiver perturbs the developmental trajectory of threat-elicited behavior. Indeed, it is possible that this form of trauma, where the infant's safety signal or "safe haven" (the caregiver) is actually the source of the threat, produces distinct outcomes across development.

Adverse Behavioral Changes in Adult Mice Following Neonatal Repeated Exposure to Pain and Sucrose

Sucrose is recommended for the treatment of pain during minor procedures in preterm infants in the neonatal intensive care unit (NICU) and is currently used worldwide as the standard of care. We recently reported that adult mice repetitively exposed to sucrose compared to water during the first week of life, irrespective of exposure to an intervention, had significantly smaller brain volumes in large white matter, cortical and subcortical structures (e.g., hippocampus, striatum, fimbria). These structures are important for stress regulation and memory formation. Here, we report the effects of repeated neonatal exposure to pain and sucrose on adult behavior in mice. Neonatal C57BL/6J mice (N = 160, 47% male) were randomly assigned to one of two treatments (sucrose, water) and one of three interventions (needle-prick, tactile, handling). Pups received 10 interventions daily from postnatal day 1 (P1) to P6. A single dose of 24% sucrose or water was given orally 2 min before each intervention. At adulthood (P60-85) mice underwent behavioral testing to assess spatial memory, anxiety, motor function, pain sensitivity, and sugar preference. We found that mice that had received sucrose and handling only, had poorer short-term memory in adulthood compared to water/handling controls (p < 0.05). When exposed to pain, mice treated with repetitive sucrose or water did not differ on memory performance (p = 0.1). A sugar preference test showed that adult mice that received sucrose before an intervention as pups consumed less sugar solution compared to controls or those that received water before pain (p < 0.05). There were no significant group differences in anxiety, motor, or pain sensitivity. In a mouse model that closely mimics NICU care, we show for the first time that memory in adulthood was poorer for mice exposed to pain during the first week of life, irrespective of sucrose treatment, suggesting that sucrose does not protect memory performance when administered for pain. In the absence of pain, early repetitive sucrose exposure induced poorer short-term memory, highlighting the importance of accurate pain assessment.