Vaginocervical stimulation selectively increases metabolic activity in the rat brain.

Vaginocervical stimulation affects progesterone secretion, sperm transport, sexual receptivity, locomotion, and perception of pain in female rats. In this experiment, vaginocervical stimulation produced statistically significant increases in the metabolic uptake of carbon-14-labeled 2-deoxy-D-glucose in the following brain areas (ordered by magnitude of uptake): medial preoptic, mesencephalic reticular formation, bed nucleus of stria terminalis, dorsal raphe, and globus pallidus. The results provide information about the concurrent processing of sensory stimulation by several neural areas and indicate that the medial preoptic area is a receiving area for copulatory stimulation.

Computer assisted analysis of 2-DG autoradiographs.

A computerized image processing system is described that assists the neurobiologists in analyzing data from 2-DG autoradiography by providing for: (1) Rapid fine-scale digitization of gray levels using a TV camera (2) The recognition of and verification of subtle differences in optical density with the aid of color windows (3) the superimposition of the autoradiographic image upon the histological image, so that the activity seen in the autoradiograph can be accurately assigned to anatomically defined structures (4) The production of numerical data suitable for statistical analysis and line drawings suitable for black on white publication (5) The relating of local gray level to a norm for the image as a whole, so as to remove the variability introduced by variations in section thickness, in the amount of 2-DG seen by the brain during incorporation, in level of anesthesia, etc. If the localized darkening in autoradiographic images is being used as an index of localized functional activity rather than as a measure of metabolism, normalization obviates the need to obtain arterial blood samples. These routines permit anatomically accurate numerical analysis of autoradiographs without any constraints on the experimental situation.

Metabolic responses to suckling in postpartum lactating rats.

The effects of suckling on the metabolic activity both of pituitary tissue and of subnuclei in the supraoptic and paraventricular nuclei of the hypothalamus were assessed by means of the [14C]deoxyglucose (2-DG) method of autoradiography. Three groups of female rats were deprived of their pups and of food for 6 h on the fifth or sixth day after parturition. Metabolic activity was assessed either before, during, or after a bout of suckling. The anterior pituitary is more active in suckled than in either non-suckled or postsuckled females. These differences may be a consequence of depletion/transformation/repletion of prolactin during a bout of suckling. The posterior pituitary is metabolically more active in suckled females and in postsuckled females than in non-suckled rats. These differences may reflect metabolic activity needed for the dynamics of oxytocin release and the restoration of ionic gradients. The dorsal and ventral subdivisions of the supraoptic nucleus and the lateral, dorsal, and posterior subnuclei of the paraventricular nucleus were more active in postsuckled females than in non-suckled females. These metabolic changes in the subnuclei of the magnocellular neurohypophysial system may reflect increased resynthesis of oxytocin (and vasopressin) in the cell bodies following a bout of suckling.

Group housing of pregnant mice reduces copulatory receptivity of female progeny.

To assess the effect of perinatal environment on adult reproductive behavior, masculine and feminine sexual behaviors of offspring from group-housed C57BL/6J parental females were compared to behaviors of offspring from control parental females housed in male/female pairs. Female offspring born to and raised by previously group housed parental females were less sexually receptive following ovariectomy and hormone replacement than offspring of control parental females. Male offspring born to and raised by previously group-housed parental females exhibited shorter latencies to ejaculation and shorter anogenital distances than offspring of control parental females. Fostering and cross-fostering, procedures to control for the effects of group-housing on maternal behavior, both increased the frequency of abnormal scrotal sacs. Group housing during pregnancy alters the adult reproductive behavior of the offspring. The reduction of receptivity in female offspring could play a role in cyclical changes in population density of confined groups.

Oviposition of fertile eggs and postponement of subsequent egg laying in ring doves (Streptopelia risoria).

Within the 45 days after an oviposition, fewer female doves which had laid fertile eggs laid a subsequent clutch than did females which had laid infertile eggs. During incubation the fertile eggs were replaced by infertile ones; therefore, this difference was not a result of raising squabs.