Behavioural and biochemical effects of haloperidol during the oestrous cycle of the rat.

The effects of two doses (1 and 2 mg/kg, i.p.) of haloperidol (HAL) on catalepsy, on concentrations of DA and DOPAC in frontal cortex, nucleus accumbens and striatum and on serum levels of oestradiol were investigated in intact female rats during the 4-day oestrous cycle. Catalepsy induced by haloperidol did not vary much during phases of the cycle. The turnover of DA in the cortex induced by haloperidol was significantly greater on proestrus and smaller on oestrus. The effect of haloperidol on the turnover of DA in the nucleus accumbens and in striatum was marginally affected by the oestrous cycle being greatest on oestrus. The levels of serum oestradiol were higher on proestrus and lower on oestrus. No significant differences were detected between diestrus and metestrus. After haloperidol there was a dramatic increase in serum oestradiol on oestrus, a slight increase on metestrus and diestrus and a decrease on proestrus. However, serum levels of oestradiol were not significantly different between phases of the cycle in rats treated with haloperidol. The results indicate that the oestrous cycle has a detectable influence on DAergic mechanisms in the frontal cortex and possibly in the tuberoinfudibular system, brought about by treatment with haloperidol.

Estrogen treatment to ovariectomized rats modifies morphine-induced behavior.

Two weeks after surgery, ovariectomized (OVX) rats were treated for 3 days with either 17 beta-estradiol (10 or 100 micrograms/kg, SC, per day) or the oil vehicle. They were then tested for morphine-induced hyperactivity (4 mg/kg, IP), analgesia and catalepsy (15 and 20 mg/kg, IP) 24 or 72 hr after the last steroid or oil injection. Estradiol treatment did not affect the locomotion or the sensitivity to nociceptive stimuli of OVX rats and did not induce a cataleptic state in animals. Estradiol- (100 micrograms/kg) treated OVX rats exhibited attenuated morphine-induced hyperlocomotion regardless of the time that had elapsed after estradiol treatment cessation, attenuated morphine-induced catalepsy at 24 hr after estradiol treatment and unaltered morphine-induced analgesia. OVX rats treated with a lower estradiol dose (10 micrograms/kg) exhibited significantly increased morphine-induced analgesia and slightly increased catalepsy. The results show that the sensitivity of brain opiate systems controlling some of the behavioral effects of morphine is modified following estradiol treatment to OVX rats.

Apomorphine-induced behaviour during the oestrous cycle of the rat.

The effect of various doses of apomorphine (APO) (25, 250, 400 and 750 micrograms/kg, s.c.) on open field behaviour, stereotyped behaviour, body temperature and concentrations of serum oestradiol was studied in cycling females and in ovariectomized rats. With the exception of grooming, the hormonal variations during the cycle, or the ovariectomy, did not have an effect on behaviour related to stimulation of presynaptic dopamine (DA) receptors. The endocrine status on proestrus (PE), characterized by an increase in serum oestradiol, did influence hyperlocomotion and hypothermia induced by apomorphine; the former being attenuated and the latter increased, as compared to the other phases of the cycle. Ovariectomy resulted in an increase in the stimulatory effect of apomorphine on locomotion. Stereotypy induced by apomorphine was unaltered by hormonal variations during the cycle and it was slightly attenuated by removal of the ovaries. During phases of low levels of oestrogen (oestrus, metestrus) apomorphine significantly increased the levels of serum oestradiol, determined 30 min after the administration of drug. It is concluded that the various DAergic mechanisms in brain are differentially affected by hormonal variations during the cycle and by ovariectomy.

Diazepam-induced place preference conditioning: appetitive and antiaversive properties.

The place conditioning paradigm was used to examine the reinforcing properties of diazepam. Rats were injected with diazepam (0.5-5.0 mg/kg, IP) and 30 min later were confined for 30 min to one side of a shuttle box, in which each of the two compartments had distinctive features. On alternate (control) days they received vehicle injections and were confined for 30 min to the opposite side. At almost all doses tested, diazepam produced place preference for the distinctive compartment that had been previously associated with the drug. Preference for the drug side developed regardless of whether diazepam was paired or unpaired with the least-preferred side, and regardless of whether testing was carried out in the undrugged or in the drugged state. The rats preferred the drug side over a novel compartment, but they did not change their initial preference for the side when diazepam was given after removal from the training box. Animals injected with meprobamate (70 mg/kg, PO), a non-benzodiazepine anxiolytic, also developed conditioned preference for the drug side, comparable to that seen following cocaine hydrochloride (10 mg/kg, IP). The diazepam (2.5 mg/kg)-induced place preference was antagonized by CGS 8216 (3 mg/kg, IP), picrotoxin (2 mg/kg, IP) and naloxone (0.8 mg/kg, SC), injected 3 min before and 15 and 20 min after diazepam respectively. Sodium valproate (200 mg/kg, IP) did not influence diazepam (1 mg/kg)-induced place preference. Sodium valproate by itself had marginal effects on place conditioning. Picrotoxin and naloxone, but not CGS 8816, produced place aversion which, in the case of picrotoxin, was due to state dependent learning.(ABSTRACT TRUNCATED AT 250 WORDS)

Pollution monitoring systems based on resonance absorption measurements of ozone with a "tunable" CO(2) laser: some criteria.

Measurements have been made with a line tunable CO(2) laser on ozone in order to establish some useful criteria for pollution monitoring via the direct absorption scheme. The absorption coefficient a and the pressure dependence of the extinction coefficient k(nu)(P) at frequencies nu corresponding to the P(8) to P(36) vibration-rotation lines of the CO(2) laser have been measured. Good agreement has been found with theory (within the framework of Lorentz and Doppler broadenings) for these experimental observations. It has been found that foreign gas species lines within +/-0.1 cm(-1) of the laser line can contribute significantly to the absorption process if their absorption intensities are not more than an order of magnitude below the intensity of the gas species being monitored.