Sex-dependent behavioral effects of chronic nicotine during adolescence evaluated in young adult rats tested in Hole-Board.

As one of the leading causes of death and serious illnesses, tobacco smoking remains a significant issue in modern societies. Many individuals smoke during adolescence, a trend that has been exacerbated by the prevalence of vaping among young people. In this context, studying the behavioral effects induced by nicotine administration in male and female rats, during the adolescent period, assumes great importance because it can help to better understand the dynamics underlying tobacco use in the two sexes. For this purpose, we employed 4 groups of rats, 2 male and 2 female groups, chronically treated with saline or nicotine 3 mg/kg i.p. for 30 days, spanning from postnatal day 30 to postnatal day 60. Utilizing quantitative analyses and T-pattern detection and analysis, our findings revealed a complex and multifaceted behavioral reorganization in adolescent rats subjected to chronic nicotine administration. Specifically, we observed an increase of anxiety in males and a reduction in females. The distinctive structural changes, induced by chronic nicotine in both sexes, have significant implications, from a translational perspective, for studies on nicotine dependence disorders.

Early alterations of the behavioural structure of mice affected by Duchenne muscular dystrophy and tested in open-field.

Present study has been carried out to assess whether early alterations of the behavioural structure may be detected in mice affected by Duchenne muscular dystrophy (DMD). To this purpose, both quantitative and T-pattern analysis (TPA) were used to analyse the behaviour of two groups of male, two months old mice, 18 MDX and 18 normal as control, tested in an open-field apparatus. T-pattern analysis is a multivariate technique able to reveal hidden structural features of behaviour and, in particular, its temporal characteristics. As to quantitative analyses, mean durations evidenced a significant increase of Walking, Modified Climbing and Rearing and a significant reduction of Immobile-Sniffing, Paw Licking and Immobility in MDX animals. A similar outcome was present in mean occurrences where the only difference was a significant result in Climbing rather than Immobile Sniffing. In addition, mean occurrences, evaluated for all the behavioural components, showed a significant increase for MDX mice. As to TPA, control mice performed 78 different T-patterns occurring 9500 times, whereas in MDX group 47 different T-patterns occurring 7082 times. Overall, MDX mice showed T-patterns of significantly shorter length. Finally, percent distribution of T-patterns encompassing each component of the behavioural repertoire showed significant differences between Control and MDX groups in all the behavioural components, except Climbing. Results suggest that the combined use of quantitative and temporal pattern analyses offers a useful approach to deeply investigate from a behavioural point of view pre-symptomatic stages of DMD in humans and related animal models as well.

Effects of the benzodiazepine inverse agonist FG7142 on the structure of anxiety-related behavior of male Wistar rats tested in hole board.

RATIONALE: Little is known about the structural characteristics of the behavior of rats with enhanced anxiety level. To fill this gap, a study was undertaken where effects of an anxiogenic drug were examined on behavioral structure of rats tested in hole board. OBJECTIVES: This study investigates effects of increased anxiety level on the structure of the behavior of rats tested in hole board METHODS: Different doses of FG7142 (1, 4, 8 mg/kg IP), a potent anxiety-inducing drug, were administered to three groups of male Wistar rats. A further group was administered saline. Experiments were recorded through a digital camera. Quantitative and multivariate approaches were applied. RESULTS: Percent distributions and durations showed increases of immobile sniffing, rearing, head dip, and edge sniff and a significant reduction of grooming activities and of walking. In addition, a decrease of head dip/edge sniff ratio was detected. Transition matrices evidenced that FG7142 provoked evident modifications of behavioral structure mainly of general exploration of environment and focused exploration of the hole. Finally, adjusted residuals showed a reduced effectiveness of FG7142 on transitions from head dip to edge sniff; on the contrary, transitions from edge sniff to head dip underwent evident dose-dependent changes. CONCLUSIONS: Present study provides a useful tool to analyze behavioral responses to different anxiety conditions. Accordingly, it is demonstrated that a condition of increased anxiety deeply modifies the structure of male Wistar rat's behavior in hole board. In addition, our results suggest that evaluation of head dip/edge sniff ratio can be considered a reliable index to appraise effects of pharmacological manipulation of anxiety and related behavioral elements.

The effects of morphine on the temporal structure of Wistar rat behavioral response to pain in hot-plate.

RATIONALE: The largest amount of researches on the hot-plate test was carried out using quantitative assessments. However, the evaluation of the relationships among the different elements that compose the behavioral response to pain requires different approaches. Although previous studies have provided clear information on the behavioral structure of the response, no data are available on its temporal structure. OBJECTIVES: The objective of this study was to investigate the temporal structure of the behavioral response to pain in Wistar rat tested in hot-plate and how this structure was influenced by morphine-induced analgesia. METHODS: The behavior of four groups of subjects tested in hot-plate, one administered saline and three with different doses (3, 6, 12 mg/kg) of morphine IP, was analyzed by means of quantitative and t-pattern analyses. The latter is a multivariate technique able to detect the existence of statistically significant temporal relationships among the behavioral events in time. RESULTS: A clear-cut influence of morphine on quantitative parameters of the response to the noxious stimulation was observed. T-pattern analysis evidenced profound structural changes of behavior. Twenty-four different t-patterns were identified following saline, whereas a dose-dependent reduction was observed following morphine. Such a reduction was accompanied by a decrease of the total amount of t-patterns detected. CONCLUSIONS: Morphine, by reducing the effects of the noxious stimulation, orients animal behavior prevalently toward exploratory t-patterns. In addition, it is suggested that the temporal structure of the response is very quickly organized and adapted to environmental noxious cues.

Acute nicotine induces anxiety and disrupts temporal pattern organization of rat exploratory behavior in hole-board: a potential role for the lateral habenula.

Nicotine is one of the most addictive drugs of abuse. Tobacco smoking is a major cause of many health problems, and is the first preventable cause of death worldwide. Several findings show that nicotine exerts significant aversive as well as the well-known rewarding motivational effects. Less certain is the anatomical substrate that mediates or enables nicotine aversion. Here, we show that acute nicotine induces anxiogenic-like effects in rats at the doses investigated (0.1, 0.5, and 1.0 mg/kg, i.p.), as measured by the hole-board apparatus and manifested in behaviors such as decreased rearing and head-dipping and increased grooming. No changes in locomotor behavior were observed at any of the nicotine doses given. T-pattern analysis of the behavioral outcomes revealed a drastic reduction and disruption of complex behavioral patterns induced by all three nicotine doses, with the maximum effect for 1 mg/kg. Lesion of the lateral habenula (LHb) induced hyperlocomotion and, strikingly, reversed the nicotine-induced anxiety obtained at 1 mg/kg to an anxiolytic-like effect, as shown by T-pattern analysis. We suggest that the LHb is critically involved in emotional behavior states and in nicotine-induced anxiety, most likely through modulation of monoaminergic nuclei.

The effects of different basal levels of anxiety on the behavioral shift analyzed in the central platform of the elevated plus maze.

The aim of the present research was to study the effects of different basal levels of anxiety on the behavioral shift studied in the central platform of the elevated plus maze. To this purpose, quantitative and multivariate analyses, the latter based on transition matrix elaboration, were carried out on Wistar and on DA/Han rats the latter belonging to a strain characterized by different reactivity to anxiogenic stimuli. Wistar rats spent 74.11±5.11 s in the central platform, whereas DA/Han significantly more: 127.08±9.87. Per cent distributions evidenced a clear-cut difference in walking activities (46.25% in Wistar, 28.4% in DA/Han rats) and in the sniffing activities (45.82% in Wistar, 62.54% in DA/Han). Mean frequencies of each behavioral element showed in DA/Han strain a value significantly lower than in Wistar for central-platform entry, open arm-entry and closed-arm entry and a significant higher value for central- platform sniffing, open-arm sniffing and corner-rearing. Moreover, the ratio open-arm entry/open-arm sniffing and closed-arm entry/closed-arm-sniffing showed significant higher values in the Wistar strain. Finally, by means of hierarchical clustering analysis, strong differences between the two strains were observed in the behavioral architecture: a cascade-shaped dendrogram, branching from Walking activities, indicates that Wistar rat behavior is oriented to cross the central platform so to rapidly reach an arm; on the contrary, the dendrogram of DA/Han rats displays a behavior heavily oriented toward the permanence in the central platform. The results show that different basal levels of anxiety provoke significant differences in the behavioral shift studied in the central platform of the elevated plus maze. Such differences, evidenced by means of transition matrices elaboration, might represent the behavioral expression of anxiety-induced modifications of decision making process underlying behavioral shift activities.