The conditioning of dyspneic suffocation fear. Effects of carbon dioxide concentration on behavioral freezing and analgesia.

Previous studies in our laboratory have shown that a single exposure to 100% carbon dioxide (CO2) can serve as an effective unconditioned stimulus (US) in a Pavlovian aversive-context conditioning paradigm in rats. Although the US exposure parameters employed in the initial studies were sufficient for producing a context-specific enhancement of behavioral freezing and analgesia, it had yet to be determined whether variations of these CO2 conditioning procedures would produce other conditioning effects. Thus, the purpose of the following experiment was to investigate the intensity of the US on the conditioned response (CR).

The nucleus accumbens as a site of action for rewarding properties of testosterone and its 5alpha-reduced metabolites.

Testosterone (T)'s positive hedonic effects may be mediated by actions of its metabolites, dihydrotestosterone (DHT) or 3alpha-androstanediol (3alpha-diol), in the nucleus accumbens (NA). In Experiment 1, adult, intact, male rats were systemically administered 1 mg of T, DHT, 3alpha-diol or vehicle, at different time points to examine concentrations of androgens in the NA. Rats administered 3alpha-diol had significantly increased concentrations of 3alpha-diol in the region of the brain encompassing the NA.

The testosterone metabolite and neurosteroid 3alpha-androstanediol may mediate the effects of testosterone on conditioned place preference.

The abuse of androgens may be related to their ability to produce positive, hedonic interoceptive effects. Conditioned Place Preference (CPP) has been used in many experiments to examine hedonic effects of drugs. This review is focused on studies from our laboratory that utilized CPP to examine potential positive hedonic effects of testosterone (T), and its androgenic metabolite dihydrotestosterone (DHT), and its metabolite 3alpha-androstanediol (3alpha-diol).

The testosterone metabolite and neurosteroid 3alpha-androstanediol may mediate the effects of testosterone on conditioned place preference.

Testosterone (T) and pregnane neurosteroids can enhance conditioned place preference (CPP). The present experiment examined CPP produced by T and its androgenic metabolite dihydrotestosterone (DHT) and 3alpha-Androstanediol (3alpha-diol; an androstane neurosteroid). Administration of 3alpha-diol (>DHT>T) to intact male Long-Evans rats, 1.

Sex differences in relation to conditioned fear-induced enhancement of morphine analgesia.

A number of studies have reported that both the immediate and proactive effects of exposure to a shock stressor are less pronounced in female than in male rats. A separate area of research has demonstrated that female rats are less sensitive to the analgesic effects of morphine than males. Experiments from our laboratory, as well as others, have found that exposure to a context associated with shock (i.